ALBERT

Description: European pear is a flooding-sensitive species, and for its cultivation in lowland areas, it is necessary to carry out the grafting of scions of commercial pear varieties into rootstocks belonging to flooding-tolerant wild pear species. Flooding tolerance of Pyrus boissieriana —a type of wild pear—was studied as a promissory rootstock for commercial pear. For this purpose, 3-month-old plants of P. boissieriana were subjected for 30 days to control ( C ), well-irrigated treatment, short-term (15 days) flooding plus 15 days recovery (F + R) and long-term (30 days) continuous flooding (F). Physiological performance, plant morphological changes and biomass accumulation were assessed. Results showed that, although stomatal conductance, transpiration and photosynthesis were progressively decreased by flooding, when flooding was short term (i.e., 2 weeks, F + R treatment) plants were able to adequately recover their physiological activity (50–74 % with respect to controls). In contrast, when plants continued to be flooded (F treatment), the physiological activity became null and the plants died quickly after the water subsided. Adventitious rooting was the most conspicuous registered morphological response to flooding, despite that flooded plants had shorter shoots and roots than control plants. Leaf and root biomass were 63 and 89 % higher under short-term flooding (F + R) than under continuous flooding (F), condition in which plants did not survive. In conclusion, P. boissieriana appears to be a promising species for its use as rootstock of commercial pear in lowland areas prone to flooding of up to 2 weeks. However, if the flooding period is extended, plants of this species are at risk of perishing.

Description: Altitudinal variation in morphological, physiological and biochemical characteristics between two provenances of Abies faxoniana Rehd. et Wils. from contrasting elevations (3,500 and 2,850 m) was investigated by reciprocal transplantations in the eastern Qinghai-Tibetan Plateau. From each altitude, 54 seedlings were selected, of which 27 seedlings were simply transplanted at their original altitude, while the other 27 seedlings were reciprocally transplanted to another altitude. The results showed that there is evident altitudinal variation in growth, photosynthetic capacity and water use efficiency among A. faxoniana seedlings. Transplantation of seedlings to a lower altitude decreased the leaf pigment content, leaf N content and water use efficiency, but increased CE, P n , LMR and PNUE, consequently promoting NAR, the biomass accumulation and branchlet length increment. Besides, the increase in the C/N ratio reduced the risk of pathogen attack. Based on the substantial plasticity in the responses of the seedlings, we infer that the ongoing climate warming might facilitate the growth of A. faxoniana seedlings at high altitudes.

Description: Tree-ring chronologies are important indicators of pre-instrumental, natural climate variability. Some of the longest chronologies are from northern Fennoscandia, where ring width measurement series from living trees are combined with series from sub-fossil trees, preserved in shallow lakes, to form millennial-length records. We here assess the recent ends of such timeseries by comparing climate signals and growth characteristics in central and northern Sweden, of (1) trees growing at lakeshore micro-sites (representing the source of sub-fossil material of supra-long chronologies), with (2) trees collected in dryer micro-sites several meters “inland”. Calibration trials reveal a predominating June–September temperature signal in N-Sweden and a weaker but significant May–September precipitation signal in C-Sweden. At the micro-site level, the temperature signal in N-Sweden is stronger in the lakeshore trees compared to the inland trees, whereas the precipitation signal in C-Sweden remains unchanged among the lakeshore and inland trees. Tree-rings at cambial ages 〉40 years are also substantially wider in the lakeshore micro-site in C-Sweden, and juvenile rings are more variable (and wider) in the dryer micro-site in N-Sweden (compared to the adjacent micro-sites). By combining the data of the various micro-sites with relict samples spanning the past 1,000 years, we demonstrate that growth rate differences at the micro-site scale can affect the low frequency trends of millennial-length chronologies. For the supra-long chronologies from northern Fennoscandia, that are derived from sub-fossil lake material, it is recommended to combine these data with measurement series from only lakeshore trees.

Description: Little is known about variations in tree phenology and their driving forces on the Tibetan Plateau. Herein, we monitored shoot growth and needle unfolding of Smith fir ( Abies georgei var. smithii ) between 3,800 and 4,360 m a.s.l. in the Sygera Mountains, southeastern Tibetan Plateau. The trees were 0.45–1.48 m high and 12–39 years old. Their phenology was observed every week between May 5 and August 26, 2011. With increasing elevation, shoot growth and needle unfolding started increasingly later, thus indicating a thermal driving force. Although the weekly shoot increment was decreasing with increasing elevation, height growth at various elevations ended in the same week, implying other factors than temperature being responsible for the end of height growth. The accumulated heat sum for the onset of shoot growth appeared to be lower between 4,200 and 4,360 m than between 3,800 and 4,000 m. The anticipated spring warming will likely induce an earlier onset of shoot growth, whereas shoot growth will apparently not benefit from autumn warming. However, the lack of long-term data records precluded a robust statistical test of the underlying cause-and-effect relationships involved in the phenological variations of height growth and needle unfolding.

Description: We investigated the physiological responses of Tibetan juniper ( Sabina tibetica ) to changes in the atmospheric CO 2 concentration ( C a ) and climate on the northeastern Tibetan Plateau based on annual tree-ring δ 13 C values since 1850. Intrinsic water-use efficiency ( iWUE ) increased, and the internal to ambient CO 2 ratio ( C i /C a ) showed no significant trend from 1895 to 1974 in the study region, indicating an active response to changing C a . The long-term trends in iWUE in the naturally occurring trees were mainly caused by the anthropogenic increase in C a . However, from 1975 to 2002, iWUE increased rapidly at the study site (by 12.4 % compared with the overall mean from 1850 to 2002), which is greater than the expected increase due only to an active response to C a . Our analysis showed that decreased water availability caused by greater evaporation due to decreased precipitation and a warming growth environment from 1975 to 2002 may have reduced stomatal conductance, leading to a higher iWUE . The warming climate and increased C a accounted for 83.6 % of the variance in iWUE of Tibetan juniper on the northeastern Tibetan Plateau from 1975 to 2002.

Description: The seeds of chilgoza pine ( Pinus gerardiana ) show moderate germination and not retain better germinability under normal ambient storage. In the present study, five storage containers [polythene bags (C 1 ), plastic jars (C 2 ), canvas bags (C 3 ), earthen pots (C 4 ) and tin boxes (C 5 )] and four temperature regimes (19–22 °C) (room temperature, T 1 ), 0 ± 1 °C (T 2 ), −4 ± 1 °C (T 3 ) and 4 ± 1 °C (T 4 ) were tested and the suitable seed storage conditions of chilgoza pine to retain viability were standardized. The storage devices preserve and retain viability trend of C 4  〉 C 3  〉 C 1  〉 C 2  〉 C 5 and T 2  〉 T 3  〉 T 4  〉 T 1 in the species throughout the storage period. However, the interaction treatment (C 4 T 2 ) of earthen pots under 0 ± 1 °C temperature regime maintained significantly ( P  〈 0.05) maximum germinability after 9 months (58.3 %) followed by C 3 T 2 and C 4 T 3 (47.5 %) as compared to other storage conditions. Notably, a sharp decline in germinability was recorded in seeds stored in tin boxes placed at room temperature. The implementation of these results for conservation management, especially nursery development and sustainable utilization of P. gerardiana in Himalayan region, has been suggested.

Description: Euphrates poplar ( Populus euphratica ) is a key species of Tugai forests in the central Asian deserts and has been the topic of dendrochronological studies in west China since the 1980s. However, little is known about its growth performance at its highest occurrence in the southern Qaidam Basin of the northern Tibetan Plateau. Increment cores of the Euphrates poplar population there did well cross-date and thus showed a high dendrochronological potential. Its growth was persistently positively correlated with temperature from previous September to current August although not significant throughout. The annual precipitation of around 41 mm can not exert any significant effect on Euphrates poplar growth in view of the extremely high annual pan evaporation of 2,150 mm. Water in the nearby Tuolahai River is limited to the period from June–September. The positive correlation of tree growth with spring/early summer temperature indicates that the riparian Euphrates poplar trees may benefit from an increasing river runoff due to an advanced and accelerated snow and glacier melting under warmer conditions. An above-average autumn/early winter temperature in the preceding year may lead to an extended water flow in the river bed and hence to an increased tree growth in the next year. It is crucial to protect this invaluable natural forest from undue human activity.

Description: The growing season of high-elevation forests will presumably lengthen in response to warming. However, little is known about long-term effects of an extended growing season, particularly on the Tibetan Plateau. Based on a strong correlation between the daily mean temperatures at an automatic weather station at timberline (4,390 m a.s.l.) in the Sygera Mts., recorded since 2007, and at the meteorological station at Nyingchi (3,000 m a.s.l.), recorded since 1960, we modeled the variation in daily mean temperature at the timberline back to 1960. The onset and end of the growing season at the timberline were determined by the first and the last day within a year when the mean daily air temperature equals or exceeds, respectively falls below, +5 °C for at least 5 days. From 1960 to 2010, the estimated length of the growing season at the timberline has significantly extended by 21.2 days, resulting mainly from a significant delay of its end (by 14.6 days) rather than from an earlier onset (by 6.6 days). Nevertheless, the variation of the length of the growing season did not exhibit any significant effect on the radial growth of Smith fir at the timberlines. Thus, tree-ring width is still a reliable proxy for summer temperature.

Description: As a transitional zone between westerlies and the Asian Monsoon system, the northeastern part of the Tibetan Plateau (NETP) is highly sensitive to climate change. The record of historical regional moisture variation in the NETP is essential for understanding climatic variation and its relationship with different climate systems in this area. Using principal component analysis, a time series was extracted from sixteen moisture-sensitive tree-ring series to investigate the regional moisture variation in the NETP over the past 150 years. We find that the first principal component (PC1) represents 46.9 % of the total variance, reflecting a common growth response to the climate factor. A spatial correlation analysis of PC1 with the gridded meteorological data demonstrated that the precipitation in May–June was the major factor in controlling tree-ring growth. Further analysis indicated that the westerlies had a sustained influence on rainfall in the NETP over the past 150 years. In addition, the rainfall in the NETP may be closely associated with the East Asian Monsoon (EAM). Severe drought years commonly correspond to years of a negative phase of the North Atlantic Oscillation and stronger EAM years over the past 150 years.

Description: Changes in age of the hydraulic architecture of Ulmus minor and U. minor  ×  U. pumila juvenile wood were studied and related to tolerance to Dutch elm disease (DED). The xylem vessel dimensions and the conductivity to air of 2- to 7-year-old branches were analyzed and quantified. No obvious differences in vessel length distribution and conductivity were found to explain differences in DED tolerance among the U. minor clones, or, at the taxon level, the higher DED tolerance of U. minor  ×  U. pumila. Among the U. minor clones, the more susceptible one had wider vessels and a higher maximum vessel diameter than the more tolerant clone. Relations between vessel lengths, vessel diameters and branch sizes were highly significant, and varied between taxa. The diameter and length of vessels increased with age, and average values stabilized 1–2 years earlier for U. minor than for U. minor  ×  pumila . Mean maximum vessel length was significantly higher in U. minor and increased more with age and maximum vessel diameter than in U. minor  ×  pumila . With each 0.2 m increase in height up the stem, conductivities for U. minor and U. minor  ×  U. pumila decreased by 59 and 50 %, respectively, probably due to shortening of the vessels. The implications of xylem structure for the means of pathogen movement and resistance to DED are discussed.

Description: Somatic embryogenesis in cork oak ( Quercus suber L.) is an efficient tool that allows the production of large number of embryos from selected quality and productive trees. Temporary immersion systems (TIS) are an alternative to semi-solid or liquid culture that combine the advantages of liquid culture and avoid the associated problems. Parameters that affect the TIS multiplication efficiency of Q. suber L. embryogenic cultures were evaluated. Immersion frequencies of 1 min every 6 or 4 h increased the fresh weight 3.7 or 7.5-fold compared with an immersion frequency of 1 min every 12 h or cultures on semi-solid medium, respectively. The cellular fate of embryogenic cultures was also affected by the immersion frequency, 1 min every 6 h was the best for mass propagation of proliferative developmental stages (embryogenic calli and embryo clusters) while 1 min every 4 h promoted the formation of single, fully developed cotyledonary embryos. An initial amount of 1.5 g fresh weight of proliferative tissues produced the best results in RITA ® containers while 0.5 g of embryogenic callus was the best for semi-solid cultures.

Description: A tree’s crown interacts with atmospheric variables such as CO 2 , temperature, and humidity. Physioecology of leaves/needles (e.g. δ 13 C, mobile carbohydrates, and nitrogen) is, therefore, strongly affected by microclimate in and surrounding a tree crown. To understand the physiological responses of leaves to changes in air temperature and moisture, we measured δ 13 C, soluble sugars, starch, and total nitrogen (N) concentrations in current year and 1-yr-old needles of Pinus koraiensis trees, and compared the growing season air temperature and relative humidity within and outside P. koraiensis crowns along an elevational gradient from 760 to 1,420 m a.s.l. on Changbai Mountain, NE China. Our results indicated that needle N and mobile carbohydrates concentrations, as well as needle δ 13 C values changed continuously with increasing elevation, corresponding to a continuous decrease in air temperature and an increase in relative humidity. Needle carbon and nitrogen status is highly significantly negatively correlated with temperature, but positively correlated with relative humidity. These results indicate that increases in air temperature in combination with decreases in relative humidity may result in lower levels of N and mobile carbohydrates in P. koraiensis trees, suggesting that future climate changes such as global warming and changes in precipitation patterns will directly influence the N and carbon physiology at P. koraiensis individual level, and indirectly affect the competitive ability, species composition, productivity and functioning at the stand and ecosystem level in NE China. Due to the relatively limited range of the transect (760–1,420 m) studied, further research is needed to explain whether the present results are applicable to scales across large elevational gradients.

Description: The seasonal cambial activity of five tropical tree species was investigated at Khao Yai National Park. The species studied were Tetrameles nudiflora , Magnolia baillonii, Canarium euphyllum Kur , Toona ciliata , and Spondias axillaris . Cambial activity was quantified by counting layers of undifferentiated cells in the cambium zone from wood anatomical micro sections prepared from wood samples collected in monthly intervals from July 2010 to June 2011. The relationship between cambial activity and climatic factors was investigated by using Pearson’s correlation. The growth dynamics of five studied species differed considerably. The cambium of Tetrameles nudiflora and Magnolia baillonii was most active when rainfall reached its maximum amount in June (mid rainy season), whereas the cambium of Canarium euphyllum , Toona ciliata , and Spondias axillaris was most active in March during the transition from the dry to the wet season.

Description: Dendrochronological research in Southeast Asia is under development; however, the amount of tress with potential for dendrochronological studies is restricted. For example, teak trees from India, Myanmar, Thailand, and Java are valuable dendrochronologic studies for ready climate response. Teak from Java is best suited for studying the El Niño-Southern Oscillation and sea-surface temperatures, whereas Indian teak is used to reconstruct periods of drought in India. Further, Thai teak and Vietnamese cypress trees captured the long drought period that led to the demise of the Angkor reign (fourteenth–fifteenth century). Diverse techniques including anatomical observation, cambial markings, cell differentiation, and isotopic analysis prove the age and growth of invisible tropical tree rings. A number of invisible growth rings in trees from both tropical and subtropical forests have been identified, resulting in the advancement of dendrochronology. Climate change is a substantial challenge for most living things and natural resources. A greater understanding of tree species adaptation in this region is necessary. The understanding of long-term paleoclimate can be gained by researching old samples and archaeological materials from this region.

Description: This paper illustrates the effects of abrupt stem burial (burial depth ~0.5 m) on tree growth in mature (46 ± 8 years) European larch ( Larix decidua Mill.) trees. In contrast to the previous research, which was mostly carried out with saplings and on experimental sites where regular aggradation occurred through the transport of sand, this work focuses on the impact of natural, abrupt burial of mature trees with rocks contained in a sandy-silty matrix typical for debris flows in mountainous headwater catchments. The effect of burial is assessed radially and axially within the stem and over almost three decades after burial. The analysis of growth disturbances and their intensity was based on the 143 cross sections (572 growth series) taken at 10-cm intervals from 6 Larix decidua Mill. The results show quite clearly that abrupt burial causes massive suppression of radial growth as compared to pre-event conditions (mean 77 %, min 38 %, max 92 %, SD 7.2 %). The trees sampled were unable to resume pre-burial growth rates even after 25 years, but recovered to reference growth conditions (as measured in undisturbed, local reference trees) after 15 years (min 3 years, max 25 years, SD 9 years). The results differ only insignificantly between different heights along the tree axis and suppression is equally well expressed at different radial positions within the stem.

Description: Individual tree-ring width chronologies and mean chronologies from Pinus tabuliformis Carr. (Chinese pine) and Sabina przewalskii Kom. (Qilian juniper) tree cores were collected and analyzed from two sites in the eastern Qilian Mountains of China. The chronologies were used to analyze individual and time-varying tree-ring growth to climate sensitivity with monthly mean air temperature and total precipitation data for the period 1958–2008. Climate–growth relationships were assessed with correlation functions and their stationarity and consistency over time were measured using moving correlation analysis. Individuals’ growth–climate correlations suggested increased percentages of individuals are correlated with certain variables (e.g., current June temperature at the P. tabuliformis site; previous June, December and current May temperature and May precipitation at the S. przewalskii site). These same climatic variables also correspond to the mean chronology correlations. A decreased percentage of individuals correlated with these climatic variables indicates a reduced sensitivity of the mean chronology. Moving correlation analysis indicated a significant change over time in the sensitivity of trees to climatic variability. Our results suggested: (1) that individual tree analysis might be a worthwhile tool to improve the quality and reliability of the climate signal from tree-ring series for dendroclimatology research; and (2) time-dependent fluctuations of climate growth relationships should be taken into account when assessing the quality and reliability of reconstructed climate signals.

Description: The ecological behaviors of a network of pure evergreen oak stands ( Quercus suber L. and Quercus ilex L.) in the Central-Western Mediterranean Basin were investigated toward climatic and edaphic factors implemented with the application of topographic wetness index (TWI). A Categorical Principal Component Analysis (Catpca) using climatic and soil physico-chemical parameters was performed on 23 cork oak and holm oak pure stands with the aim to understand better the effectiveness of TWI for characterizing soil ecology of the two species. Catpca pointed out that, although cork oak and holm oak are able to growth in similar Mediterranean conditions, they show different behaviors in terms of needs and tolerance to soil water content. TWI confirmed such results at local scale, allowing highlighting some interesting features of the species differential ecology. Although both species confirmed to be drought-tolerant, the heliophilous cork oak revealed to dominate the landscape on wettest soils with high TWI values—indicating the capacity to tolerate stresses due to periods of waterlogging—, while the shade-tolerant holm oak prevails for low-medium TWI values—drier and mesophilous sites. Despite the application of TWI to vegetation science and ecology is relatively recent, results are encouraging and suggest considering this user-friendly and synthetic index in ecological investigations and modeling.

Description: Key message Use of wood ash or a mixture of wood and oil shale ashes increases the concentrations of P and K in the assimilation organs of conifers and stimulates tree growth. Abstract The effect of fertilization with wood ash (10 and 15 t ha −1 ) and a mixture of wood ash (10 t ha −1 ) and oil shale ash (8 t ha −1 ) on the growth (height, root collar diameter, biomass, biomass production) and nutrient concentrations in subsoil and needles of young Pinus sylvestris and Picea abies plants on the Puhatu (Northeast Estonia) cutaway peatland in the first 2 years were studied. After the second growing year differences in the average height growth of P. abies and P. sylvestris were statistically significantly higher on ash-treated plots than on the control plots ( p  〈 0.05), being respectively 1.4–1.6 and 1.5–1.7 times greater than height growth of the control trees. The best results on root collar diameter were observed on mixture ash treatments: the root collars were 1.9 ( P. abies ) and 2.2 ( P. sylvestris ) times larger than of the control trees. The biomass of the two conifer species and the biomass production of P. sylvestris in 2012 was the greatest on the mixture ash treatments. Five months after fertilization with ashes the concentrations of P, K, Ca and Mg were higher on the treated plots than on the control plot. Although the concentrations of P and K in P. sylvestris needles rose after the treatment with ash, seedlings suffered from P and K deficiency. The concentrations of P and K in P. abies needles were on optimum. The P/N and the K/N ratios in needles were also improved compared to control trees needles.

Description: Key message Variation in tree biomass among African savanna species of equal size is driven by a wide inter-specific variation in wood specific gravity. Abstract Tree form and taper is a fundamental component of tree structure and has been used for over a century in forestry to estimate timber yields and in ecological theories of scaling laws. Here, we investigate variation in form factor in the context of biomass in African savannas. Biomass is a fundamental metric of vegetation state, yet in African savannas it remains unclear whether variation in form factor F (taper) or wood specific gravity ( G ) is a more dominant driver of biomass differences between tree species of equal stem diameter and height. Improving our knowledge of vertical mass distribution in savanna trees provides insight into differences in life strategies, such as tradeoffs between production, disturbance avoidance, and water storage. Here, we destructively harvested 782 stems in a savanna woodland near Kruger National Park, South Africa, and measured whole tree wet mass, wood specific gravity, water content, and form factor. We found that three of four dominant species can vary in mass by over twofold, yet inter-specific variation in taper was low and taper did not vary significantly between common species ( P  〉 0.05) (species-mean form factors ranged from F  = 0.57 to 0.77, where cone F  =  $0.\bar{3}$ 0 . 3 ¯ , quadratic paraboloid F  = 0.5, cylinder F  = 1.0). Comparison of a general biomass allometry model to species-specific models supported the conclusion that the large difference in biomass between species of the same size was explained almost entirely ( R 2  = 0.97) by including species-mean G with D and H in a general allometric equation, where F was constant. Our results suggest that inter-specific variation in wood density, not form factor, is the primary driver of biomass differences between species of the same size. We also determined that a simple analytical volume-filling model accurately relates wood specific gravity of these species to their water and gas content ( R 2  = 0.68). These results indicate which species use a wide spectrum of water storage strategies in savanna woodlands, adhering to a trade-off between the benefits of denser wood or increased water storage.

Description: Key message Frequent cloud immersion events result in direct uptake of cloud water and improve plant water potentials during daylight hours in saplings of two dominant cloud forest species. Abstract In ecosystems with frequent cloud immersion, the influence on plant water balance can be important. While cloud immersion can reduce plant water loss via transpiration, recent advances in methodology have suggested that many species also absorb water directly into leaves (foliar water uptake). The current study examines foliar water uptake and its influence on daily plant water balance in tree species of the endangered spruce–fir forest of the southern Appalachian Mountains, USA. These mountain-top communities are considered relic, boreal forests that may have persisted because of the benefits of frequent cloud immersion. We examined changes in needle water content, xylem water potentials, and stable isotope values in saplings of the two dominant tree species, Abies fraseri and Picea rubens before and after a 24 h period of experimental cloud immersion. Both species exhibited foliar water uptake following immersion, evidenced by substantial changes in stable isotope values of extracted needle water that reflected the composition of the fog water. In addition, total needle water content improved 3.7–6.4 % following experimental submersion and xylem water potentials were significantly greater (up to 0.33 MPa) in cloud-immersed plants over control plants. These results indicate that foliar water uptake may be an adaptive strategy for utilizing cloud water and improving overall tree vigor in these most southerly distributed boreal species.

Description: Key message This study is the first to quantify tree water use below 50°S. Tree morphology differs markedly among the two investigated species, reflecting adjustment to different environmental cues. Abstract A pronounced environmental gradient dictates the dominance of Nothofagus in the foothills on the eastern side of the Andes Mountains in Patagonia, Argentina. Below 50° southern latitude, open forests of Nothofagus antarctica (ñire) dominate the landscape towards the Patagonian steppe where annual rainfall is low. With increasing rates of annual rainfall, corresponding with an increase in elevation, closed forests of N. pumilio (lenga) replace those of ñire. During a short-term study we assessed differences in stand structure and examined environmental, structural and functional traits related to tree water use of ñire and lenga. Sap velocity reached similar maximum rates (95–100 L m −2  sapwood h −1 ), but whole-tree water use ( Q ) was significantly lower in ñire (8–13 L day −1  tree −1 ) compared to lenga (20–90 L day −1  tree −1 ) resulting in lower stand transpiration (ñire: 0.51 mm day −1 ; lenga: 3.42 mm day −1 ) despite similar tree densities. Related to this, wind speed had a particularly significant impact on Q of ñire, but not lenga. The ratio of leaf area to sapwood area ( A L / A S ) clearly identified ñire to be more structurally proficient at conserving water. While stem diameter (DBH) and crown area ( A C ) were well related in both species, only lenga exhibited relationships between variables related to tree allometry and physiology ( A C / Q , DBH/ Q ). Our results provide the first ecophysiological characterization of the two Nothofagus species that define important and widespread ecosystems in southern Patagonia (not only below 50°S), and provide useful data to scale water use of both species from tree to stand.

Description: Life history theory posits that an increased investment in reproduction should result in decreased vegetative investment. Switching resources from growth to reproduction are also expected in species experiencing selection pressure for high variation of seed crops. In this study, we tested whether the reproductive effort of trees, measured as the number of fruits produced, is related to their radial growth increment. We examined a population of Sorbus aucuparia , a fleshy-fruited tree species with highly variable interannual individual fruit production growing in the subalpine zone and under strong selection pressure from pre-dispersal seed predators. We used 12-year data to test the relationship between fruit crop and radial growth increments in current, previous and subsequent years, and found no trade-off between growth and reproduction. For almost all trees, there was no correlation between fruit crop and radial growth increment in the same year or next year. Only a few trees showed a positive correlation between fruit crop and previous-year growth. In the statistics, we took advantage of the high variability of individual fruit crops in high production years. In four heavy crop years, we compared the radial growth increments of trees with heavy crops with those of trees with low fruit crops. Current and next-year radial growth did not differ between trees with low and high fruit crops. In all those years, however, trees having heavy fruit crops had higher previous-year growth increments. We suggest that the harsh subalpine weather conditions account for the lack of a trade-off between growth and reproduction in the studied population.

Description: Key message Strategies for sampling trees for wood density must consider within-tree variations of density; theoretically and empirically developed sampling strategies can lead to accurate estimations of mean density. Abstract Wood density is a highly variable functional trait of trees with large differences occurring between species as well as between and within trees of a given species, which is a potential source of uncertainty in forest biomass estimations. Because of the within-tree variation, sampling trees for density in certain locations within the bole (e.g., breast height) can be biased. This study is an attempt to develop and test sampling strategies that yield more representative estimates of whole-tree density by incorporating information on radial and vertical density variations. In this study, 76 trees of 6 tree species from China and Germany were destructively sampled and analyzed for radial and vertical density profiles. The species exhibit different patterns and magnitudes in their density variations. Theoretical approximation points for linear radial and vertical density trends were derived mathematically. The best sampling position was found to be at 1/3 of the tree height and at 2/3 of the radial distance from pith to bark (“strategy 2”). Different sampling strategies as estimators for the mean wood density of the species were simulated, tested and compared. Strategy 2 yielded the best estimates of wood density, while BH (breast height) increment core density at 2/3 radial distance (Wiemann approximation) and BH increment core mean density were slightly less accurate. Sampling-based estimates reduced uncertainty about 5 % relative to database estimates. As a more feasible alternative to strategy 2, adapted sampling strategies based on increment cores at breast height could be developed empirically for the six species.

Description: Key message Conduct comprehensive field studies and laboratory tests to determine geometrical and material properties of pneumatophores. They are shown to be rigid under hydrodynamic loading, and deflection of the root tip caused by normal flow drag is less than 1   mm. Abstract An investigation into the characteristics of Sonneratia alba mangrove roots was performed to improve our understanding of physical processes in mangrove ecosystems. Field studies were carried out in mangrove areas along the coastline of Singapore where S. alba mangrove species are found. Geometrical properties, such as height, diameter and spatial density of the cone-shaped pneumatophores were assessed through the use of photogrammetric methods. Samples of these roots were harvested from mangrove swamps and their material properties, including the mass density, moisture content, Young’s modulus and bending strength, were determined in the laboratory. The bending strength and Young’s modulus of the woody core of the pneumatophores of the S. alba are found to be around 800 MPa, and these values are larger compared to those belonging to other lateral plant roots. It was observed that for the pneumatophores, the Young’s modulus for tensile and flexural modulus under bending are approximately the same. Based on resonance and deflection calculations, our results indicate that S. alba pneumatophores in a mangrove environment under riverine hydrodynamic loadings can be regarded as rigid. The natural frequency of the pneumatophores is an order of magnitude larger than the forcing frequency of the flow during normal tidal current, suggesting that strong amplitudes are not likely to be observed because of the vortex-induced vibration (VIV) in water flow. The deflection of the root tip for S. alba pneumatophores (simulated as cylindrical cantilever) caused by normal flow drag is less than 1 mm, i.e., about 1/200 of the root height, and this suggests that the hydro-elastic model is not necessary for simulating pneumatophores in laboratory and numerical model under tidal flows.

Description:    We studied the effects of climatic factors on tree-ring width and vessel lumen area (VLA) in earlywood of English oak ( Quercus robur L.) in Latvia. Cores were obtained from healthy canopy oaks in 40 stands located across Latvia. Tree-ring widths and VLA were measured. Principal component analysis was used to arrange the sites along gradients of response of tree-ring width and earlywood to environmental factors. Significant relationships of tree-ring width and mean VLA with climatic factors (mean monthly temperature and precipitation sum) were determined by correlation analysis. Relationships between tree-ring, early- and latewood widths were tested in three sampled stands. The patterns of response of VLA and tree-ring width to environmental factors differed in relation to a west–east gradient of increasing continentality. Three regions of Latvia (western, central and eastern) were distinguished along this gradient. Responses to climate differed between tree-ring width and mean VLA. Occurrence of significant correlations between climatic factors and the proxies differed between regions, likely due to regional differences in temperature and precipitation. Tree-ring width correlated with climatic factors (most commonly with March, May and June temperature and August precipitation of the current growing season and July–August temperatures of the previous growing season); VLA was more strongly related to climatic factors, particularly with temperature in winter and spring months. The proportion of significant correlation coefficients with climatic factors differed between the regions. Among sites, significant correlation of tree-ring width with temperature in spring and summer was more frequent in the western region, while correlation with winter temperature of the previous growing season and precipitation in August was more frequent in the eastern region. For VLA, the frequency of significant correlation coefficients with temperature in winter and spring was higher in the eastern region. Content Type Journal Article Category Original Paper Pages 1-16 DOI 10.1007/s00468-012-0701-z Authors Roberts Matisons, Faculty of Biology, University of Latvia, Kronvalda bulv.4, Riga, LV-1010 Latvia Guntis Brūmelis, Faculty of Biology, University of Latvia, Kronvalda bulv.4, Riga, LV-1010 Latvia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Stem CO 2 efflux ( E S ) is an important component of forest ecosystem carbon budgets and net ecosystem CO 2 exchange, but little is known about E S in temperate forests in Northeastern China, an area with a large extent of forest. We measured E S along with stem temperature at 1 cm depth ( T s) over a 9 month period in 2007 on ten dominant tree species of secondary forests of the region. Other measurements included the autotrophic component of soil CO 2 efflux ( E A ) and stem diameter at breast height (DBH). Our objectives were to (1) examine the seasonal patterns and species differences in E S , and (2) determine the correlations between E S and T s, DBH and E A . Mean E S for the measurement period ranged from 1.09 to 1.74 μmol CO 2  m −2  s −1 among the ten species. The sensitivity of E S to T s ( Q 10 ) ranged from 1.87 to 2.61. Across the ten species 57–89% of variation in E S was explained by T S and DBH. There was also a linear relationship between mean E S and E A . E S was better predicted by T s in the dormant season than the growing season, indicating that additional factors such as growth respiration and internal transport of CO 2 in the xylem became more important contributors to E S during the growing season. Stem CO 2 efflux increased, and Q 10 decreased, with increasing DBH in all species. Although temperature exerts strong control on the rate of cellular respiration, we conclude that in tree stems in situ, T S , DBH and many other factors affect the relationship between CO 2 evolution by respiring cells and the diffusion of CO 2 to the stem surface. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0698-3 Authors J. Y. Yang, Center for Ecological Research, Northeast Forestry University, Harbin, 150040 China R. O. Teskey, Warnell School of Forestry and Natural Resources, University of Georgia, Athens, 30602 USA C. K. Wang, Center for Ecological Research, Northeast Forestry University, Harbin, 150040 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    We analyzed the leaf phenology of European beech ( Fagus sylvatica ) and its variation due to spatial and temporal climatic variability, using a modified data set of the phenological network in Slovenia. We used first leaf unfolding (LU) and general leaf colouring (LC) time series of 47 sites (altitudes from 55 to 1,050 m a.s.l.) and corresponding climate series (52 of precipitation and 38 of temperature) for the period 1955–2007, collected by the Environmental Agency of the Republic of Slovenia. Across the network in average, LU occurred from 14 April until 13 May, and LC from 3 October until 29 October. LU was delayed by 2.6 days and LC was promoted by 1.9 days when the altitude increased by 100 m. Year-to-year variation of LU was significantly correlated with March and April temperatures. March temperatures had a greater effect at lower elevations and April ones at higher elevations. LC was related to August and September temperatures, and occurred later if the temperatures were higher. Recently, March and April temperatures showed an increasing trend and LU occurred 1.52 days earlier per decade at 1,000 m a.s.l. but no significant shifts were observed at lower altitudes. August temperatures were also increasing but the trends of LC were not significant and were not clearly related to altitude. Our detailed sub-regional data from a relatively small area with high geographic variability showed that changes in climate affect phenological response, mainly leaf unfolding, to a greater degree at higher altitudes than at lower ones. Content Type Journal Article Category Original Paper Pages 1-10 DOI 10.1007/s00468-012-0686-7 Authors Katarina Čufar, Department of Wood Science and Technology, Biotechnical Faculty, University of Ljubljana, Rožna Dolina, Cesta VIII/34, 1000 Ljubljana, Slovenia Martin De Luis, Department of Geography, University of Zaragoza, y O.T. C/Pedro Cerbuna 12, 50009 Zaragoza, Spain Miguel Angel Saz, Department of Geography, University of Zaragoza, y O.T. C/Pedro Cerbuna 12, 50009 Zaragoza, Spain Zalika Črepinšek, Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia Lučka Kajfež-Bogataj, Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Tsuga canadensis is often considered a foundation species because of its influence on the biological and ecological processes of upland forest systems. With hemlock woolly adelgid ( Adelges tsugae ; HWA)-induced mortality of T. canadensis in southern Appalachian upland forests, there is a crucial need to understand the regeneration dynamics of this tree species. This research was conducted within mature T. canadensis forests of Great Smoky Mountains National Park (GSMNP) prior to widespread HWA infestation. Tsuga canadensis regeneration abundance is lower than has been reported in more northern locales, but varies widely among sites in the southern Appalachian Mountains. Ordination results suggest landscape-scale patterns of regeneration abundance that are influenced by gradients in understory Rhododendron maximum cover, soil sand and nutrient content. Regression models reinforce the observed gradients in regeneration abundance. Sites with abundant T. canadensis regeneration have less R. maximum cover, soil sand and litter depth, but more soil nutrient availability. Tsuga canadensis seedlings and saplings tend to be spatially aggregated at the 14 × 21 m plot scale. Sites with spatially aggregated seedlings and saplings have greater canopy openness and more species with gap affinity. This research elucidates associations between successful T. canadensis regeneration and site factors such as soil nutrient availability and canopy dynamics. More forest surveys are required to understand the conditions necessary for successful T. canadensis regeneration. Land managers involved in forest restoration efforts may have to utilize appropriate silvicultural techniques conjoined with R. maximum removal operations to regenerate T. canadensis in southern Appalachian upland forests. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0681-z Authors Joshua A. Kincaid, Environmental Studies Department, Shenandoah University, 1460 University Drive, Winchester, VA 22601, USA Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    To contribute to a deeper understanding of interspecific relations between wood and tree size variables, 23 angiosperm tree species in two East African rain forests were investigated. The tree size variables were maximum tree height, maximum diameter, and maximum crown area. Wood was analyzed in regard of the physical variables specific gravity, water and gas fraction as well as the chemical variables carbon content and nitrogen content. All three tree size variables showed a significantly positive relation to each other. The wood physical variables showed negative correlations between the gas fraction and both specific gravity and the water fraction. Also positive relations were found between the water fraction and nitrogen content and between wood specific gravity and carbon content. Between tree size and wood physical variables, the gas fraction showed positive relations to both maximum tree height and diameter, while wood specific gravity was negatively related to maximum tree height and diameter. No significant correlations were found between the wood physical variables and the maximum crown area. Relationships among tree size variables can be explained by static constraints, while relations between the wood physical variables can be explained by a trade-off underlying structure and survival to support the species specific life strategy and tree architecture. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0687-6 Authors Gabriel Sebastian Becker, Institute of Botany, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany Désirée Braun, Institute of Botany, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany Robert Gliniars, Institute of Botany, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany Helmut Dalitz, Institute of Botany, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Afforestation and reforestation activities enjoy a prominent place on the policy agenda as potential tools to sequester carbon and for biomass production to mitigate climate change and restoring marginal lands. Two provenances (1 from Turkey and 1 from Lebanon) of the species Cedrus libani A. Rich. and two provenances (1 from Morocco and 1 from France) of the species Cedrus atlantica (Endl.) Carrier were studied to evaluate to what degree these trees were suitable for afforestation in arid regions of Italy. We measured, seasonal stomatal conductance ( g s ), foliar morphology, foliar carbon isotopic composition (δ 13 C), growth, and assessed bud phenology in a split plot trials. Bud phenology showed that the Turkish and Lebanon provenances of C. libani gave rise to earlier buds (earlier bud provenances) than the Moroccan and French provenances of C. atlantica (later bud provenances) with a mean difference of 23.2 days. Both provenances showed similar bud phenology and seasonal stomatal conductance ( g s ) especially in April–May (earlier bud provenances) and June (later bud provenances). The foliar δ 13 C was negatively correlated with g s in both the earlier bud provenances (i.e., an increase in g s was accompanied by decreasing foliar δ 13 C values) and the later bud provenances. The stomatal conductance values measured over a growth season showed significant correlations with daily means of both temperature and relative humidity. Hence g s in the earlier bud provenances was correlated with daily temperature in spring, whereas correlations with relative humidity were found in later bud provenances in both late spring and summer. We concluded that the earlier bud provenances ( C. libani ) are not suitable in areas affected by both summer drought and late spring frosts, whereas the later bud provenances ( C. atlantica ) are more suitable to be used in future afforestation plans due to their greater tolerance to summer drought. Content Type Journal Article Category Original Paper Pages 1-7 DOI 10.1007/s00468-012-0692-9 Authors Giovanni di Matteo, CRA-PLF, Agricultural Research Council, Research Unit for Wood Production Outside Forests, Via Valle della Quistione 27, 00166 Rome, Italy Marco Riccardi, CRA-PLF, Agricultural Research Council, Research Unit for Wood Production Outside Forests, Via Valle della Quistione 27, 00166 Rome, Italy Francesco Righi, CRA-PLF, Agricultural Research Council, Research Unit for Wood Production Outside Forests, Via Valle della Quistione 27, 00166 Rome, Italy Ernesto Fusaro, CRA-PLF, Agricultural Research Council, Research Unit for Wood Production Outside Forests, Via Valle della Quistione 27, 00166 Rome, Italy Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Fingered citron ( Citrus medica L. var. sarcodactylis Swingle), a precious fruit ornamental plant, is sensitive to low temperature. Cold tolerance, evaluated by semi-lethal temperature, was lower in wild-type ‘Qingpi’ than in its mutant ‘Aihua’ trees obtained by γ-radiation. The full-length cDNAs of two genes encoding fatty acid desaturases involved in unsaturated fatty acid biosynthesis were isolated from the fingered citron leaves. The CmsFAD2 open reading frame (ORF) had 1,152 bp and was uninterrupted, encoding a polypeptide of 384 amino acids that showing 82% homology with the microsomal ω-6 desaturase CiFAD2 in Davidia involucrate . The CmsFAD8 ORF contained 1,373 bp and 7 introns, encoding a polypeptide of 458 amino acids showing 76% homology with the plastidial ω-3 desaturase BpFAD8 in Betula pendula . CmsFAD2 was expressed highly in leaves but low in roots and flowers, while CmsFAD8 was obviously expressed in three tissues. Compared with control group (28°C), the expression of CmsFAD2 and CmsFAD8 in leaves of two genotypes was significantly induced at 6°C. The increase of CmsFAD2 and CmsFAD8 was earlier and larger in cold-tolerant ‘Aihua’ than in cold-sensitive ‘Qingpi’. The linolenic acid content increased significantly in leaves of mutant ‘Aihua’ plants exposed to low temperature of 6°C. The results showed that a positive relationship between CmsFAD expression and genotype tolerance to cold may exist. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0695-6 Authors Ling Yang, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004 Zhejiang, China Jin Ye, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004 Zhejiang, China Wei-Dong Guo, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004 Zhejiang, China Chang-Chun Wang, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004 Zhejiang, China Hai-Tao Hu, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004 Zhejiang, China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Leaf gas-exchange, leaf and shoot anatomy, wood density and hydraulic conductivity were investigated in seedlings of Quercus suber L. grown for 15 months either at elevated (700 μmol mol −1 ) or normal (350 μmol mol −1 ) ambient atmospheric CO 2 concentrations. Plants were grown in greenhouses in a controlled environment: relative humidity 50% (±5), temperature similar to external temperature and natural light conditions. Plants were supplied with nutrients and two water regimes (WW, well watered; WS, water stress). After 6 months exposure to CO 2 enrichment an increase in photosynthetic rate, a decrease in stomatal conductance and a decrease in carbon isotope discrimination (Δ 13 C) were observed, along with enhanced growth and an increase in the number of branches and branch diameter. Over the same period, the shoot weight ratio increased, the root weight ratio decreased and the leaf weight ratio was unaffected. The specific leaf area increased due to an increase in total leaf thickness, mainly due to the palisade parenchyma and starch. However, after 9 and 15 months of elevated CO 2 exposure, the above-mentioned physiological and morphological parameters appeared to be unaffected. Elevated CO 2 did not promote changes in vessel lumen diameter, vessel frequency or wood density in stems grown in greenhouse conditions. As a consequence, xylem hydraulic efficiency remained unchanged. Likewise, xylem vulnerability to embolism was not modified by elevated CO 2 . In summary, elevated CO 2 had no positive effect on the ecophysiological parameters or growth of water stressed plants. Content Type Journal Article Category Original Paper Pages 1-13 DOI 10.1007/s00468-012-0691-x Authors M. Vaz, Departamento de Biologia, Instituto de Ciências Agrárias e Ambientais Mediterrânicas (ICAAM), Universidade de Évora, Apartado 94, 7002-554 Évora, Portugal H. Cochard, INRA, UMR 547 PIAF, 63100 Clermont-Ferrand, France L. Gazarini, Departamento de Biologia, Instituto de Ciências Agrárias e Ambientais Mediterrânicas (ICAAM), Universidade de Évora, Apartado 94, 7002-554 Évora, Portugal J. Graça, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017 Lisbon, Portugal M. M. Chaves, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017 Lisbon, Portugal J. S. Pereira, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017 Lisbon, Portugal Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    The effect of stone dust deposition on the rate of transpiration in Shorea robusta was studied in three principal seasons in a polluted forest in comparison to an almost non-polluted forest. The extent of particulate pollution was determined by measuring suspended particulate matter in the air and dust fall on leaf surface. Macroscopic and microscopic leaf injury symptoms were studied. Scanning electron microscopic examination of leaf surfaces revealed a number of foliar anomalies. Qualitative determination of rate of transpiration in field condition was done by ‘cobalt chloride method’. It was found that transpiration was diminished as a result of foliar dust deposition which not only caused blockage of stomatal aperture but also physical damage to the leaf surface. Thus, particulate air pollution can be considered as one of the external factors regulating the rate of transpiration in plants. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0697-4 Authors Dulal C. Saha, Centre for Environmental Studies, Institute of Science, Visva-Bharati University, Santiniketan, 731235 India Pratap K. Padhy, Centre for Environmental Studies, Institute of Science, Visva-Bharati University, Santiniketan, 731235 India Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    At present, acid rain has become one of the top ten global environmental issues. Acid rain causes slower growth, injury, or decline of forests. Some dramatic effects on forests have been observed in south China since the late 1970s and the situation is deteriorating. We carried out a comparative proteomic analysis on Pinus massoniana Lamb, a staple tree species widely distributed in middle and south China to gain a better understanding of tree response to acid rain at molecular level. Two-year-old P. massoniana saplings were treated with simulated AR (SiAR) or control solution, respectively, for 8 months. The changes in total protein profile of P. massoniana leaves were studied using two-dimensional differential gel electrophoresis (2D-DIGE). Among the total protein spots reproducibly detected on each gel, 65 spots representing 28 proteins were identified to be differentially regulated. These proteins were annotated in various biological functions, such as photosynthesis and energy metabolism, secondary metabolism, protein stability, amino acid and nitrogen metabolism and defense. Down-regulation of four key enzymes in the Calvin cycle identified that biomass loss by SiAR was mainly due to the inhibition of carbon fixation. Primary energy metabolisms involved in sucrose biosynthesis, glycolytic pathway and Krebs cycle, etc., were also disturbed after SiAR treatment. Specifically, most of up-regulated proteins were related to secondary metabolism, protein stability and defense, suggesting that in response to SiAR stress, plants started a variety of metabolic pathways to prevent cells from damage. Different from the herbaceous plants suffering SiAR, it revealed that secondary metabolites in P. massoniana play pivotal roles against SiAR. Protemoic techniques were demonstrated a reliable and robust tool to expand our understanding of differentially expressed proteins associated with acid rain stress on P. massoniana . Functional analysis of these proteins further revealed biochemical and physiological basis of the plant in response to acid rain and would provide strategies for breeding new acid rain tolerant tree species. To our knowledge, it is the first proteome report on the forest plant suffering long-term acid rain stress. Content Type Journal Article Category Original Paper Pages 1-13 DOI 10.1007/s00468-012-0799-z Authors Xiaoqin Wang, College of Biological Science and Engineering, Beijing University of Agriculture, Beijing, 102206 China Zheng Liu, College of Life Sciences, Hebei University, Baoding, 071002 China Li Niu, Xiamen University, Xiamen, 361005 China Bin Fu, Xiamen University, Xiamen, 361005 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Natural hybridization commonly produces individuals with intermediate morphological and genetic characteristics, but their response to environmental stress is still uncertain, with some studies showing that transgressive performance would be common. Prosopis chilensis and Prosopis flexuosa are the most important tree species from Arid Chaco, South-America. Both species occupy different ecological niches in terms of water availability. Genetic and morphological studies have demonstrated the existence of interspecific hybrids in contact areas between these species. Hybrids are characterized by clear intermediate morphological characteristics, which have taxonomical value, and genetic structure compared to both parental species. We studied mechanisms implicated in drought stress tolerance in seedlings of P. chilensis , P. flexuosa and their interspecific hybrids trying to elucidate if hybrids have a morpho-physiological, growth and survival intermediate response to drought compared to differential parental responses or if they out-perform both parental species when subjected to drought. Our results suggest that hybridization does not result in individuals with intermediate mechanisms related to drought resistance, but with a unique trait combination leading to high growth when water availability is high (similar to the most vulnerable parental species) and high survival under drought stress (similar to the more resistant parental species). Certain uncoupling between symplastic and apoplastic resistence to drought was observed in hybrids, as well as decreased physiological-wood anatomical plasticity compared to parental species. The long-term consequences in terms of adaptive response to drought of this particular trait combination of hybrids remain still unknown. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0798-0 Authors Diego A. López Lauenstein, Instituto de Fisiología y Recursos Genéticos Vegetales (IFRGV) Instituto Nacional de Tecnología Agropecuaria (INTA), Camino a 60 cuadras Km 5.5, Córdoba, Argentina María E. Fernández, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina Aníbal R. Verga, Instituto de Fisiología y Recursos Genéticos Vegetales (IFRGV) Instituto Nacional de Tecnología Agropecuaria (INTA), Camino a 60 cuadras Km 5.5, Córdoba, Argentina Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Estimation of total leaf area (LA T ) is important to express biochemical properties in plant ecology and remote sensing studies. A measurement of LA T is easy in broadleaf species, but it remains challenging in coniferous canopies. We proposed a new geometrical model to estimate Norway spruce LA T and compared its accuracy with other five published methods. Further, we assessed variability of the total to projected leaf area conversion factor (CF) within a crown and examined its implications for remotely sensed estimates of leaf chlorophyll content ( C ab ). We measured morphological and biochemical properties of three most recent needle age classes in three vertical canopy layers of a 30 and 100-year-old spruce stands. Newly introduced geometrical model and the parallelepiped model predicted spruce LA T with an error 〈5 % of the average needle LA T , whereas two models based on an elliptic approximation of a needle shape underestimated LA T by up to 60 %. The total to projected leaf area conversion factor varied from 2.5 for shaded to 3.9 for sun exposed needles and remained invariant with needle age class and forest stand age. Erroneous estimation of an average crown CF by 0.2 introduced an error of 2–3 μg cm −2 into the crown averaged C ab content. In our study, this error represents 10–15 % of observed crown averaged C ab range (33–53 μg cm −2 ). Our results demonstrate the importance of accurate LA T estimates for validation of remotely sensed estimates of C ab content in Norway spruce canopies. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0774-8 Authors Lucie Homolová, Laboratory of Geo-Information Science and Remote Sensing, Wageningen University, Droevendaalsesteeg 3, 6708 PB Wageningen, The Netherlands Petr Lukeš, Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 986/4a, 60300 Brno, Czech Republic Zbyněk Malenovský, Remote Sensing Laboratories, Department of Geography, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland Zuzana Lhotáková, Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Viničná 5, Prague, Czech Republic Věroslav Kaplan, Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 986/4a, 60300 Brno, Czech Republic Jan Hanuš, Global Change Research Centre, Academy of Sciences of the Czech Republic, Bělidla 986/4a, 60300 Brno, Czech Republic Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    In the context of global warming, it is of high importance to assess the influence of climatic change and geographic factors on the radial growth of high-elevation trees. Using tree-ring data collected from four stands of Qilian juniper ( Juniperus przewalskii Kom. ) across an altitudinal gradient in the central Qilian Mountains, northwest China, we compared the radial growth characteristics and climate–growth relationships at different elevations. Results indicated that there was little difference in the tree-ring parameters of the four chronologies. Correlation analyses both for unfiltered and 10-year high-passed data of monthly climatic variables and chronologies were presented to investigate the climatic forcing on tree growth, and results revealed that the correlation patterns were consistent among the four sites, especially for high-passed data. We employed the principal components analysis method to obtain the first principal component (PC1) of the four chronologies and computed the correlations between PC1 and climate factors. The PC1 correlated significantly with winter (November–January) temperature, prior August and current May temperature, and precipitation in the previous September and current January and April, indicating that tree growth in this region was mainly limited by cold winter temperature and drought in early growing season and prior growing season (prior August and September). However, the climate–growth relationships were unstable; with an increase in temperature, the sensitivity of tree growth to temperature had decreased over the past few decades. Considering the instability of the climate–growth relationships, climate reconstructions based on tree rings in the study area should be approached with more caution. Content Type Journal Article Category Original Paper Pages 1-10 DOI 10.1007/s00468-012-0776-6 Authors Linlin Gao, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Xiaohua Gou, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Yang Deng, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Wenhuo Liu, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Meixue Yang, State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000 China Zhiqian Zhao, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    We assessed growth differences and the foliar traits underpinning production in paired samples of juvenile American beech ( Fagus grandifolia Ehrh.) that originated from seed versus root sprouts. Root sprouts had significantly greater relative extension growth rate and slightly greater leaf mass per unit area compared to seed-derived individuals, but neither light-saturated net photosynthetic rate nor foliar chlorophyll and nitrogen concentrations differed significantly between paired seedlings and sprouts. The greater height growth rate of saplings originating as root sprouts does not result from differing foliar function, but rather depends on translocation of assimilates from the parent tree to sustain this unusual and ecologically important dual regeneration strategy in American beech. Content Type Journal Article Category Short Communication Pages 1-4 DOI 10.1007/s00468-012-0781-9 Authors Emad Farahat, Department of Biology, McGill University, 1205 Avenue Dr. Penfield, H3A1B1 Montréal, QC, Canada Martin J. Lechowicz, Department of Biology, McGill University, 1205 Avenue Dr. Penfield, H3A1B1 Montréal, QC, Canada Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    European beech ( Fagus sylvatica L.) covers a large area mainly in the colline and montane ranges in Europe, and a drier and warmer climate, as expected for the coming decades, is likely to alter its distribution. So far, an altitudinal shift has been projected using a variety of modelling approaches. However, we lack knowledge about the climatic and edaphic factors that control the growth and competitive behaviour of beech at its dry distribution limit. We applied and further developed dendroecological methods to study the drought response and sensitivity pattern of beech at sites with different moisture regimes. We compared three pairs of sites from different geographical regions near the dry distribution limit of beech in Switzerland, consisting of a dry and mesic site each. Radial growth differed between mesic and dry sites, in that average ring-width at mesic sites was around double the width at dry sites. For the whole study period (1930–2006), the sites with the lowest available soil water capacity (AWC) were found to respond most sensitively to drought. However, in recent years, sites with higher AWC have shown increasing drought sensitivity, i.e. they have responded even more strongly to drought than the dry sites. This change in sensitivity corresponds to a seasonal shift in drought response at mesic sites, with a change in the months showing significant drought response in all three studied regions compared with the past. Even though dry sites generally displayed a larger number of negative pointer years than mesic sites, it appears that the frequency of pointer years has increased at mesic sites, i.e. they have become more sensitive particularly in the last quarter of the twentieth century. Yet, the frequency of pointer years at the dry sites has remained fairly constant. These results indicate that beech trees near their dry distribution limit are adapted to extreme conditions already, while changes in the growth patterns of beech under mesic conditions have to be expected. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0786-4 Authors P. Weber, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland H. Bugmann, Forest Ecology, Institute of Terrestrial Ecosystems, ETH Zürich, Zurich, Switzerland A. R. Pluess, Ecosystem Management, Institute of Terrestrial Ecosystems, ETH Zürich, Zurich, Switzerland L. Walthert, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland A. Rigling, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description: Special topic: integrating modelling and experimentation Content Type Journal Article Category Editorial Pages 1-4 DOI 10.1007/s00468-012-0778-4 Authors R. Matyssek, Ecophysiology of Plants, Technische Universität München, von-Carlowitz Platz 2, Weihenstephan, 85354 Freising, Germany G. M. J. Mohren, Forest Ecology and Forest M anagement Group, Centre for Ecosystem Studies, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Individual tree-ring width chronologies and mean chronologies from Pinus tabuliformis Carr. (Chinese pine) and Sabina przewalskii Kom. (Qilian juniper) tree cores were collected and analyzed from two sites in the eastern Qilian Mountains of China. The chronologies were used to analyze individual and time-varying tree-ring growth to climate sensitivity with monthly mean air temperature and total precipitation data for the period 1958–2008. Climate–growth relationships were assessed with correlation functions and their stationarity and consistency over time were measured using moving correlation analysis. Individuals’ growth–climate correlations suggested increased percentages of individuals are correlated with certain variables (e.g., current June temperature at the P. tabuliformis site; previous June, December and current May temperature and May precipitation at the S. przewalskii site). These same climatic variables also correspond to the mean chronology correlations. A decreased percentage of individuals correlated with these climatic variables indicates a reduced sensitivity of the mean chronology. Moving correlation analysis indicated a significant change over time in the sensitivity of trees to climatic variability. Our results suggested: (1) that individual tree analysis might be a worthwhile tool to improve the quality and reliability of the climate signal from tree-ring series for dendroclimatology research; and (2) time-dependent fluctuations of climate growth relationships should be taken into account when assessing the quality and reliability of reconstructed climate signals. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0772-x Authors Fen Zhang, Key Laboratory of Western China’s Environmental Systems (MOE), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Xiaohua Gou, Key Laboratory of Western China’s Environmental Systems (MOE), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Wenhuo Liu, Key Laboratory of Western China’s Environmental Systems (MOE), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China D. F. Levia, Departments of Geography and Plant and Soil Sciences, University of Delaware, Newark, DE 19716, USA Yingjun Li, Taiyaun Normal University Research Center for Scientific Development in Fenhe River Valley, Taiyuan, 030012 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Dendrochronological research in Southeast Asia is under development; however, the amount of tress with potential for dendrochronological studies is restricted. For example, teak trees from India, Myanmar, Thailand, and Java are valuable dendrochronologic studies for ready climate response. Teak from Java is best suited for studying the El Niño-Southern Oscillation and sea-surface temperatures, whereas Indian teak is used to reconstruct periods of drought in India. Further, Thai teak and Vietnamese cypress trees captured the long drought period that led to the demise of the Angkor reign (fourteenth–fifteenth century). Diverse techniques including anatomical observation, cambial markings, cell differentiation, and isotopic analysis prove the age and growth of invisible tropical tree rings. A number of invisible growth rings in trees from both tropical and subtropical forests have been identified, resulting in the advancement of dendrochronology. Climate change is a substantial challenge for most living things and natural resources. A greater understanding of tree species adaptation in this region is necessary. The understanding of long-term paleoclimate can be gained by researching old samples and archaeological materials from this region. Content Type Journal Article Category Review Pages 1-16 DOI 10.1007/s00468-012-0775-7 Authors Nathsuda Pumijumnong, Faculty of Environment and Resource Studies, Mahidol University, Salaya, Phutthamonthon, Nakhon Pathom 73170, Thailand Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    The branch autonomy principle has been referred to extensively for using branch cuvettes as a technique of studying ozone (O 3 ) effects within the canopy of adult forest trees. However, this principle may not hold in general regarding biochemical interactions between O 3 -impacted branches exposed inside cuvettes and neighbouring crown parts under the unchanged ambient O 3 regime. After reviewing relevant cuvette studies conducted to date, we will provide evidence that cuvette-exposed branches may serve, given awareness of outlined pre-requisites and restrictions, as surrogates for examining the crown-level response of trees to elevated O 3 regimes. Such a conclusion is based on the defence metabolism of branches, which seems to be autonomous to some extent from neighbouring crown sections. Cuvette studies may, therefore, be used to derive dose response functions as measures of O 3 sensitivity. On such grounds, also validation and improvement of stomatal O 3 uptake modelling becomes feasible. The branch-level approach, however, does not substitute whole-tree free-air O 3 fumigation and related flux assessments, as branches in view of representativeness and boundary layer characteristics represent one stage in scaling O 3 flux between leaf and tree level. Branch level-based flux scaling should be backed, therefore, by independent trunk sap-flow assessment techniques that offer derivation of FO 3 at the whole-tree level. Content Type Journal Article Category Original Paper Pages 1-10 DOI 10.1007/s00468-012-0715-6 Authors Gerhard Wieser, Division of Alpine Timberline Ecophysiology, Federal Research and Training Centre for Forests, Natural Hazards and Landscape, Rennweg 1, 6020 Innsbruck, Austria Rainer Matyssek, Ecophysiology of Plants, Technische Universität München, 85354 Freising, Germany Bernhard Götz, University of Applied Sciences, Hochschule für nachhaltige Entwicklung Eberswalde (FH), Botanical Garden, Am Zainhammer 5, 16225 Eberswalde, Germany Ludger Grünhage, Department of Plant Ecology, Justus-Liebig University Giessen, Heinrich-Buff-Ring 26, 35392 Giessen, Germany Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Understanding spatiotemporal tree growth variability and its associations with climate can provide key insights into forest dynamics in the context of global climate change. Here, we conduct a comprehensive investigation on 64 ring-width chronologies across the entire Northwest (NW) China to understand the regional patterns of tree growth and climate–growth relationships. Using rotated principal component analysis and hierarchical clustering analysis, we found that tree growth was mainly determined by the climate and could be classified into nine groups. Most of the tree-ring chronologies in NW China showed high correlations with moisture conditions in the current and previous growing seasons. After removing age-related growth trends, inter-annual tree growth patterns are supposed to be mainly determined by climate and climate–growth relationships. Since climate–growth relationships for most tree-ring chronologies in this arid region are similar, patterns of tree growth are mainly determined by climate variability. Within each group, the strength of the common signal increases under extreme climate conditions. Thus, climate plays a more important role in determining tree growth in extreme climate conditions relative to the non-climate factors, leading to more coherent growth patterns. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0721-8 Authors Keyan Fang, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Xiaohua Gou, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Fahu Chen, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Edward Cook, Tree-Ring Lab, Lamont-Doherty Earth Observatory of Columbia University, New York, NY 10964, USA Jinbao Li, International Pacific Research Center, School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96882, USA Yingjun Li, Key Laboratory of Western China’s Environmental Systems (Ministry of Education), Research School of Arid Environment and Climate Change, Lanzhou University, Lanzhou, 730000 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Tree growth and form are both influenced by crown architecture and how it effects leaf distribution and light interception. This study examined the vertical distribution of foliage in 4-year-old plantation-grown Eucalyptus pilularis Sm. and E. cloeziana F. Muell. trees. Leaf area (LA) distribution was determined at two different sites using allometric approaches to determine LA in crown sections and for whole trees. Leaf area was distributed more towards the upper crowns when canopies had been closed for longer. Leaf area was also skewed more towards the upper crowns for Eucalyptus pilularis than E. cloeziana . These species differences were consistent with differences in vertical light availability gradients as determined by point quantum sensors. Leaf area of individual branches was highly correlated with branch cross-sectional area (CSA) and whole-tree LA was closely related to stem CSA. Branch-level allometric relationships were influenced by site and crown position. However, the general allometric equations between stem size and whole-tree leaf area could be applied across sites. Results from this study suggest that pruning of live branches in these species should follow species-specific guides for the timing and height of pruning to optimise the effects on stem growth and form. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0809-1 Authors Philip J. Alcorn, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia David I. Forrester, Institute of Silviculture, Freiburg University, 79085 Freiburg, Germany R. Geoff B. Smith, Forests NSW, PO Box J19, Coffs Harbour, NSW 2450, Australia Dane S. Thomas, Forests NSW, PO Box J19, Coffs Harbour, NSW 2450, Australia Ryde N. James, Fenner School of Environment and Society, The Australian National University, Canberra, ACT 0200, Australia Adrienne B. Nicotra, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia Jürgen Bauhus, Fenner School of Environment and Society, The Australian National University, Canberra, ACT 0200, Australia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    The two main objectives of this research were to identify new S -RNase alleles in Iranian almond cultivars and to characterize naturally occurring mutations in these alleles that may cause self-compatibility. We investigated S genotypes of 22 Iranian almond cultivars using stylar RNase electrophoresis, PCR and DNA sequencing. We report six previously unidentified P. dulcis S -RNase alleles ( S 45 , S 46 , S 47 , S 48 , S 49 and S 50 ). Four of 12 tested S -RNases were found to be non-functional in vitro: S 49 , S 50 , S 24 / S na and S 25 / S 47 . Detected point mutations in the C3 coding region of S 49 - and S 50 -RNase, leading to the replacement of a highly conserved cysteine and histidine residues, are with the highest probability the reason of these S -RNases inactivity. Results also suggested that ten Iranian almond cultivars display unique S genotype. All presented data confirm Iranian cultivars as valuable almond sources which are of interest to almond breeding and conservation programs. Content Type Journal Article Category Original Paper Pages 1-14 DOI 10.1007/s00468-012-0803-7 Authors Akram Hafizi, Faculty of Agriculture, Department of Agronomy and Plant Breeding, Zanjan University, Zanjan, Iran Behrouz Shiran, Faculty of Agriculture, Department of Plant Breeding and Biotechnology, Shahrekord University, Shahrekord, Iran Bahram Maleki, Faculty of Agriculture, Department of Agronomy and Plant Breeding, Zanjan University, Zanjan, Iran Ali Imani, Sections of Horticulture, Agriculture and Natural Resources Research Centre of Karaj, Karaj, Iran Bojana Banović, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Protocols have been established to clone adult cork oak trees by somatic embryogenesis using semisolid medium. However, for economically viable mass propagation, embryogenic cultures in liquid medium need to be developed. In this study, suspension cultures were initiated from embryo clusters obtained by secondary embryogenesis on a gelled medium lacking plant growth regulators. After 6 days of culture, these embryo clusters generated high cell density suspensions that also contained small organized structures (embryos and embryogenic clumps). As the culture duration increased, tissue necrosis and fewer embryogenic structures were observed and the establishment of suspension cultures failed. An alternative method was found adequate for initiation of embryogenic suspensions: embryo clusters from gelled medium were briefly shaken in liquid medium and detached cells and embryogenic masses of 41–800 μm were used as inoculum. Maintenance of embryogenic suspensions was achieved using a low-density inoculum (43 mg l −1 ) by subculturing four embryogenic clumps of 0.8–1.2 mm per 70 ml of medium. Proliferation ability was maintained for almost 1 year through ten consecutive subcultures. The initiation and maintenance protocols first developed for a single genotype were effective when tested on 11 cork oak genotypes. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0763-y Authors Jesús Jiménez, Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA), Finca El Encín, Apdo. 127, 28800 Alcalá de Henares, Madrid, Spain Dolores López-Vela, Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA), Finca El Encín, Apdo. 127, 28800 Alcalá de Henares, Madrid, Spain Mar Ruiz-Galea, Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA), Finca El Encín, Apdo. 127, 28800 Alcalá de Henares, Madrid, Spain Cristina Celestino, Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA), Finca El Encín, Apdo. 127, 28800 Alcalá de Henares, Madrid, Spain Mariano Toribio, Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA), Finca El Encín, Apdo. 127, 28800 Alcalá de Henares, Madrid, Spain Jesús Alegre, Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA), Finca El Encín, Apdo. 127, 28800 Alcalá de Henares, Madrid, Spain Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Reduction of crop yield from high water stress is a serious agricultural problem worldwide, which is expected to intensify under future global change scenarios. Efforts are underway worldwide to improve crops resistance to drought. One possible way is the careful choice of rootstock-scion combination. It is well known that water stress symptoms of grafted cherry trees to a large extent depend on the rootstock variety. Scions grafted on dwarf rootstocks show more serious stress symptoms, so it is reasonable to hypothesize that these symptoms and the tissue structure of the rootstock stem are connected. This paper examines this connection for 1-year-old seedlings of eight cherry rootstocks with different degree of vigor. Tissue structure was observed via scanning electron microscope images. Investigations were focused on number, size, and distribution of vessels, because they are principally responsible for water transport. Stem porosity (i.e., the total vessel area relative to the stem area, in cross-sectional view) of the dwarfing rootstocks was found to be significantly smaller than that of the others, supporting the notion that stem anatomical characteristics might contribute to water stress sensitivity. Content Type Journal Article Category Original Paper Pages 1-8 DOI 10.1007/s00468-012-0766-8 Authors Anikó Hajagos, Department of Fruit Science, Faculty of Horticultural Science, Corvinus University of Budapest, Villányi út 29-43, Budapest, 1118 Hungary György Végvári, Department of Fruit Science, Faculty of Horticultural Science, Corvinus University of Budapest, Villányi út 29-43, Budapest, 1118 Hungary Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Citrus plants originate from southeastern Asia, in a large area with various climates characterized by a broad range of temperatures. Some species have been diversified in temperate climates, others in subtropical climates. Temperature is assumed to be a key factor in citrus species adaptation and diversification of basic cellular functions. In a field experiment, the tolerance of the three fundamental Citrus species C. medica L., C. reticulata Blanco and C. maxima (Burm.) Merr., and Fortunella japonica (Thunb.) Swing. to photooxidative stress caused by seasonal climatic changes was evaluated on adult trees by measuring net photosynthesis ( P net), stomatal conductance ( G s), maximum photosynthesis ( P max) and chlorophyll fluorescence ( F v/ F m). In addition, seasonal changes in oxidative status, antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase) and antioxidant metabolites (ascorbate and glutathione) were monitored. Mandarin and pummelo appeared to be the most tolerant, showing the lowest down-regulation of photosynthetic parameters, and the lowest accumulation of oxidized compounds associated with efficiency of their antioxidant system. Kumquat showed intermediate behaviour, with a large diminution of photosynthetic parameters and marked accumulation of hydrogen peroxide, whereas the malondialdehyde content remained low, with a strong induction of glutathione synthesis. Finally, citron appeared to be the most sensitive genotype with a marked decrease in photosynthetic performance, the largest accumulation of oxidative parameters, insufficient induction of antioxidant enzymes and down-regulation of ascorbate and glutathione synthesis. Content Type Journal Article Category Original Paper Pages 1-13 DOI 10.1007/s00468-012-0769-5 Authors Jérémie Santini, UR 1103 Génétique et Ecophysiologie de la Qualité des Agrumes, INRA, 20230 San Giuliano, France Jean Giannettini, Laboratoire Biochimie and Biologie Moléculaire du Végétal, CNRS, UMR 6134 SPE, 20250 Corte, France Olivier Pailly, UR 1103 Génétique et Ecophysiologie de la Qualité des Agrumes, INRA, 20230 San Giuliano, France Stéphane Herbette, INRA, UMR 547 PIAF, 63100 Clermont-Ferrand, France Patrick Ollitrault, CIRAD, UPR 75, Avenue Agropolis, TA A-75/02, 34398 Montpellier cedex 5, France Liliane Berti, Laboratoire Biochimie and Biologie Moléculaire du Végétal, CNRS, UMR 6134 SPE, 20250 Corte, France François Luro, UR 1103 Génétique et Ecophysiologie de la Qualité des Agrumes, INRA, 20230 San Giuliano, France Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Tree species use a variety of strategies to obtain resources. As a result, semi-deciduous forest species and cerrado species can grow in close proximity and in the same climate, while occupying very different vegetation types. The aim of this study was to understand the dynamic responses of Hymenaea courbaril, a forest species, and Hymenaea stigonocarpa, a cerrado species, to annual climatic variation and increasing atmospheric CO 2 concentrations under the same macroclimatic conditions. To that goal, we constructed chronologies of tree-ring width, vessel area, and intrinsic water-use efficiency (calculated from tree-ring δ 13 C content) for Hymenaea trees growing in a mosaic of the two vegetation types. Our analyses revealed that both species responded to climatic variation in similar ways, but with different intensities and at different times of year. Climate models showed that precipitation had a stronger effect on tree-ring width and earlywood vessel area of H. courbaril and temperature was slightly more determinant for H. stigonocarpa . In addition, both species showed increasing intrinsic water-use efficiency over the last five decades, but only individuals with reduced growth rate presented this trend, suggesting that those specimens in favorable growth conditions do not respond to the atmospheric CO 2 enrichment. Despite the trend in water-use efficiency found in some individuals, it did not reflect in a higher growth rate. The differences between the two species documented by us may be due to divergent sources of hydrological stress in the two vegetation types. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0764-x Authors Giuliano Maselli Locosselli, Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277, Butantã, CEP 09715-030 São Paulo, SP, Brazil Marcos Silveira Buckeridge, Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277, Butantã, CEP 09715-030 São Paulo, SP, Brazil Marcelo Zacharias Moreira, Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Avenida Centenário, 303, CEP 131416-000 Piracicaba, SP, Brazil Gregório Ceccantini, Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277, Butantã, CEP 09715-030 São Paulo, SP, Brazil Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    We applied dendroclimatological techniques to determine long-term stationarity of climate–growth relationships and recent growth trends of three widespread coniferous tree species of the central Austrian Alps, which grow intermixed at dry mesic sites within a dry inner Alpine environment (750 m asl). Time series of annual increments were developed from 〉120 mature trees of Picea abies , Larix decidua and Pinus sylvestris . Calculation of response functions for the period 1911–2009 revealed significant differences among species in response to climate variables. While precipitation in May–June favored radial growth of P. abies and L. decidua , P. sylvestris growth mainly depended on April–May precipitation. P. abies growth was most sensitive to May–June temperature (inverse relationship). Moving response function coefficients indicated increasing drought sensitivity of all species in recent decades, which is related to a decline in soil moisture availability due to increasing stand density and tree size and higher evapotranspiration rates in a warmer climate. While recent trend in basal area increment (BAI) of L. decidua distinctly declined implying high vulnerability to drought stress, moderately shade-tolerant P. abies showed steadily increasing BAI and quite constant BAI was maintained in drought-adapted P. sylvestris , although at the lowest level of all species. We conclude that synergistic effects of stand dynamics and climate warming increased drought sensitivity, which changed the competitive strength of co-occurring conifers due to differences in the inherent adaptive capacity. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0768-6 Authors Roman Schuster, Institute of Botany, Leopold-Franzens-University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria Walter Oberhuber, Institute of Botany, Leopold-Franzens-University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Stem diameter in Gallesia integrifolia (Spreng.) Harms (Phytolaccaceae) increases by forming concentric rings of xylem alternating with phloem, which show frequent anastomoses. After a period of primary growth and the formation of first (normal) ring of vascular cambium, further successive rings are initiated outside this cambium. The second ring of cambium originates from the pericycle parenchyma located between the proto-phloem, and the pericycle fibres. Each cambium produces centripetally secondary xylem and centrifugally secondary phloem. Differentiation of xylem precedes that of phloem and the first elements formed are always xylem fibres. Structurally, the vascular cylinder is composed by successive rings of secondary xylem and phloem. These rings are separated by wide bands of conjunctive parenchyma tissue. Presence of collateral vascular bundles with irregular orientation is observed in the region of anastomoses of two or more bands of conjunctive tissue. These bundles are surrounded by isodiametric, lignified and thick-walled cells. In some of the cambial rings, occurrence of polycentric rays was also noticed; these rays are tall, and characterized by the presence of meristematic regions that differentiated into thick-walled elements of secondary xylem. Origin and development of the successive cambia and the structure of xylem are discussed. Content Type Journal Article Category Original Paper Pages 1-8 DOI 10.1007/s00468-012-0762-z Authors Kishore S. Rajput, Department of Botany, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, 390002 India Diego Romeiro, Instituto Florestal, CP 1322, Sao Paulo, CEP 02377-000 Brazil Eduardo L. Longui, Instituto Florestal, CP 1322, Sao Paulo, CEP 02377-000 Brazil Carmen R. Marcati, Departamento de Recursos Naturais, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Campus de Botucatu, SP, CP 237, Sao Paulo, CEP 18603-970 Brazil Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    In the search of timber species being tolerant towards summer droughts, which are expected to be more frequent in future, Douglas-fir is often discussed as a potential alternative for spruce in Central Europe. To assess physiological and growth reactions of Douglas-fir provenances towards climate- and weather-related environmental conditions we took advantage of a provenance trial with three sites in south-western Germany located along an elevation gradient. We examined six different provenances of Douglas-fir from North America for oxygen (δ 18 O) and carbon (δ 13 C) stable isotope composition in tree rings as well as for radial increment for a 7 year period and long-term height growth. Our results show that different Douglas-fir provenances clearly vary in their drought sensitivity at the driest and warmest site in the valley as shown by the radial growth decline in the extreme dry and hot year 2003. The growth decline in the provenances Pamelia Creek, Cameron Lake, Duncan Paldi and Conrad Creek could be clearly attributed to a reduction in stomatal conductance as assessed by the relations between δ 18 O and δ 13 C in the tree rings. These responses were not related to the long-term average climate at the places of origin of the provenances and the provenances with the lowest long-term (height) growth potential were the ones least affected in radial increment by the extreme drought of 2003. When selecting suitable Douglas-fir provenances, which are adapted to the climatic conditions projected for the future we thus might need to take into account the trade-off between the adaptation to extreme drought periods and the long-term growth performance. Site-specific evaluations of the probability of extreme drought events are thus needed to select the appropriate provenances. Content Type Journal Article Category Original Paper Pages 1-16 DOI 10.1007/s00468-012-0765-9 Authors Kirstin Jansen, Institute for Landscape Biogeochemistry, Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalderstr. 84, 15374 Müncheberg, Germany Jakob Sohrt, Core Facility Metabolomics, Centre for Systems Biology (ZBSA), Albert-Ludwigs-University Freiburg, Habsburgerstr. 49, 79104 Freiburg, Germany Ulrich Kohnle, Forest Research Institute Baden-Württemberg (FVA), Wonnhaldestr. 4, 79100 Freiburg, Germany Ingo Ensminger, Forest Research Institute Baden-Württemberg (FVA), Wonnhaldestr. 4, 79100 Freiburg, Germany Arthur Gessler, Institute for Landscape Biogeochemistry, Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalderstr. 84, 15374 Müncheberg, Germany Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Mangroves are mainly tropical tree species that occur on either side of the equator and because temperature decreases with increasing latitude, the latitudinal limits of mangroves are expected to be mainly controlled by temperature-related drivers. Here, we hypothesized that the mangrove genera ( Avicennia and Rhizophora ) have the same limiting temperature at all of their upper latitudinal limits at the global scale. We first derived six parameters from monthly mean sea surface temperature (SST) and air temperature (AT). Furthermore, we investigated whether the variation in these temperature parameters is related (i) to the position of the limit, (ii) to specific temperature requirements of congeneric species and/or (iii) to aridity. All temperature-based parameters derived from AT and SST are highly variable among the upper latitudinal limits of Avicennia and Rhizophora . Hence, we found no common isotherms to characterize the limits of the two mangrove genera, which contradict previous studies. The high temperature variation among limits can be due to partial range filling towards the latitudinal limits. This is supported by the higher warmest month temperatures at the latitudinal limits of the northern hemisphere as compared to the southern hemisphere. However, temperature parameters at limits, with no or less than 250 km of available poleward coast, are not different from other limits, and adult tree height at the limits is not correlated with the temperature-based variables. Mean air temperature is warmer at limits with an arid climate, suggesting mechanisms of compensation towards higher temperatures when Avicennia and Rhizophora have to cope with both aridity and low temperature. Content Type Journal Article Category Original Paper Pages 1-13 DOI 10.1007/s00468-012-0760-1 Authors Katrien Quisthoudt, Laboratory for Plant Biology and Nature Management, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Nele Schmitz, Laboratory for Plant Biology and Nature Management, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Christophe F. Randin, Institute of Botany, Universität Basel, Schönbeinstrasse 6, 4056 Basel, Switzerland Farid Dahdouh-Guebas, Laboratory for Plant Biology and Nature Management, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Elisabeth M. R. Robert, Laboratory for Plant Biology and Nature Management, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Nico Koedam, Laboratory for Plant Biology and Nature Management, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    We examined the growth and photosynthetic responses of Japanese forest tree species to sulfur dioxide (SO 2 ) under different nitrogen (N) loads to soil. We grew Quercus serrata , Fagus crenata , Castanopsis sieboldii , Larix kaempferi , Pinus densiflora, and Cryptomeria japonica seedlings in Andisol supplemented with N as NH 4 NO 3 solution at 0, 20, and 50 kg ha −1  year −1 . Seedlings were exposed daily to charcoal-filtered air or SO 2 at 10, 20, and 40 nl l −1 for two growing seasons. Except for C. japonica seedlings, exposure to SO 2 at a relatively low concentration stimulated whole-plant growth, especially under a relatively high N load. The effects of N load on the negative impact of SO 2 on whole-plant growth were synergistic in Q. serrata , F. crenata , C. sieboldii, and P. densiflora , counteractive in L. kaempferi , and additive in C. japonica . In Q. serrata , F. crenata , C. sieboldii, and P. densiflora seedlings, the different responses of whole-plant growth to SO 2 among the N treatments were because of the effect of N load on the response of the net photosynthetic rate to SO 2 . L. kaempferi seedlings showed N load-induced tolerance of whole-plant growth to SO 2 . This was explained by the effect of N load on the responses of photosynthesis and development of assimilative organs to SO 2 . The different growth responses to SO 2 among the N treatments were explained by the effects of N load on the SO 2 uptake rate (evaluated by stomatal diffusive conductance) or the accumulated SO 2 uptake (evaluated by foliar S concentration). Content Type Journal Article Category Original Paper Pages 1-16 DOI 10.1007/s00468-012-0755-y Authors Masahiro Yamaguchi, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan Makoto Watanabe, Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan Chikako Tabe, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan Junichi Naba, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan Hideyuki Matsumura, Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, Abiko, Chiba 270-1194, Japan Yoshihisa Kohno, Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, Abiko, Chiba 270-1194, Japan Takeshi Izuta, Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    In the National Natural Reserve of the Qilian Mountains, northwest China, automated dendrometers were installed on Qilian juniper ( Sabina przewalskii Kom.) in 2010. Here, we present a complete 1-year data series of dendrometer measurements and synchronous meteorological records. The mean daily radius change index curve obtained by first-difference standardization was analyzed. The results indicate strong similarities of stem radius variations among the studied trees. By graphical inspection of sub-diurnal shrinkage and expansion patterns, seasonal stem radius variations could be divided into two general phases. During early winter to spring, daily amplitudes show strong fluctuations, and meteorological data indicate that both air and soil temperatures are positively related to stem radius swelling. From late March to early November 2011, stem radius expansion is negatively related to both air and soil temperatures, as well as to vapor pressure deficit, and positively related to precipitation and soil moisture. We found that the dividing lines between the two phases were strongly linked to the occurrence of a 0 °C daily mean air temperature, indicating that air temperature played an important effect on stem radius variations in this cold and arid environment. During the growing season in 2011, May and June are the most productive months. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0743-2 Authors Zhangyong Wang, Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou, 730000 China Bao Yang, Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou, 730000 China Annie Deslauriers, Département des Sciences Fondamentales, Université du québec à Chicoutimi, 555 boul. de l’Université, Chicoutimi, QC G7H 2B1, Canada Chun Qin, Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou, 730000 China Minhui He, Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou, 730000 China Feng Shi, Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou, 730000 China Jingjing Liu, Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou, 730000 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    The use of in vitro regenerated plants in forestry and orchard depends ultimately on the development of efficient transplantation protocols, ensuring high survival rates and successful establishment under field conditions. We tested the performance of micropropagated carob trees ( Ceratonia siliqua L.) throughout the acclimatization process in terms of survival, growth and physiological traits, including field comparisons with seed-derived and mother plants. The field trial was 100 % successful, i.e. we found no major differences between micropropagated, seed-derived and mother plants in terms of growth rate, height, number of leaves, photosynthetic efficiency, chlorophyll fluorescence, chlorophyll content and soluble protein content, although these parameters changed significantly during acclimatization. Stomatal conductance ( g s ) was reduced by fourfold when plants were transferred from in vitro culture to the growth chamber, thus preventing uncontrolled wilting. The photosynthetic rate ( P N ) was relatively low in vitro, in the growth chamber and the greenhouse, but increased to match seed-derived and mother plants in the field. The chlorophyll a / b ratio in leaves from in vitro and growth chamber plants was typical of shade plants (2.1) but became more characteristic of sun plants in the subsequent acclimatization stages (3.1–3.5). The maximum efficiency of photosystem II ( F v / F m ) remained mostly constant at ~0.80 throughout acclimatization, as is typical for healthy, non-stressed plants. We conclude that our micropropagation and acclimatization protocols provide a suitable alternative to traditional mass propagation techniques for the carob tree. Content Type Journal Article Category Original Paper Pages 1-10 DOI 10.1007/s00468-012-0753-0 Authors M. L. Osório, Institute for Biotechnology and Bioengineering, Centre of Genomics and Biotechnology (IBB-CGB), Faculty of Sciences and Technology, Ed. 8, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal J. Osório, Institute of Mediterranean Agricultural and Environmental Sciences (ICAAM), Faculty of Sciences and Technology, Ed. 8, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal S. Gonçalves, Institute for Biotechnology and Bioengineering, Centre of Genomics and Biotechnology (IBB-CGB), Faculty of Sciences and Technology, Ed. 8, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal M. M. David, Institute of Mediterranean Agricultural and Environmental Sciences (ICAAM), Faculty of Sciences and Technology, Ed. 8, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal M. J. Correia, Centro de Estudos em Ciências e Tecnologias Agrárias (CECTC), Faculty of Sciences and Technology, Ed. 8, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal A. Romano, Institute for Biotechnology and Bioengineering, Centre of Genomics and Biotechnology (IBB-CGB), Faculty of Sciences and Technology, Ed. 8, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Interactions between photosynthetic rate, transpiration, content of soluble carbohydrates, leaf dimensions and structural parameters and growth of hybrid aspen ( Populus tremula  ×  P. tremuloides Michx.) were studied in relation to soil pH and chemical composition. The investigations were conducted in two plantations on former agricultural lands in North Estonia. One plantation was established on a territory influenced for a long time by alkaline cement dust pollution before plantation establishment and the other on an unpolluted territory. At pH 7.4 and higher concentrations of Ca, K, Mg, N and P in soil on the polluted area inhibition of height growth and diameter at breast height, leaf area and dry mass was observed compared to the unpolluted plantation with an optimum soil pH of 6.7. Differences in hybrid aspen leaves in the two plantations were related to the lower net photosynthetic and transpiration rates and higher starch and sucrose contents in the polluted plantation. Leaves from alkaline soil had a thicker palisade mesophyll layer and lower number of stomata at abaxial epidermis. The relatively low N concentration in leaves in the polluted area was associated with the low height and diameter at breast height of trees. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0754-z Authors Malle Mandre, Department of Ecophysiology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Viljandi mnt 18B, 11216 Tallinn, Estonia Jaan Klõšeiko, Department of Ecophysiology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Viljandi mnt 18B, 11216 Tallinn, Estonia Aljona Lukjanova, Department of Ecophysiology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Viljandi mnt 18B, 11216 Tallinn, Estonia Arvo Tullus, Department of Silviculture, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51014 Tartu, Estonia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Previously, we found that secretory cell degradation typically occurred through programmed cell death during secretory cavity development in Citrus sinensis L. (Osbeck). This finding indicated that secretory cavities could be utilized as a new cell biology model for investigating the regulatory mechanisms of plant programmed cell death. To study further the programmed cell death during secretory cavity development in Citrus fruit, we studied the morphogenetic characteristics of secretory cavities during their development in Citrus grandis cv. Tomentosa. Using light microscope- and electron microscope-TUNEL assays, immunohistochemistry and immunocytochemistry, we described the precise spatial and temporal alterations in caspase 3-like distribution, chromatin condensation and DNA fragmentation during the programmed cell death of secretory cavity cells. Caspase 3-like was found to be significantly located in both the cytoplasm and the nucleus of secretory cavity cells undergoing programmed cell death, and caspase 3-like is closely associated with chromatin condensation and DNA fragmentation. Interestingly, both caspase 3-like and DNA fragmentation were detected in the nucleoli. Our findings suggest that caspase 3-like may be involved in the programmed cell death of secretory cavity cells, especially in chromatin condensation, DNA fragmentation, nuclear degradation and the degradation of certain organelles. Content Type Journal Article Category Original Paper Pages 1-15 DOI 10.1007/s00468-012-0752-1 Authors Peiwei Liu, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, 510642 Guangzhou, China Shejian Liang, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, 510642 Guangzhou, China Nan Yao, Guangdong Key Laboratory of Plant Resources, State Key Laboratory of Biocontrol, Sun Yat-sen University, 510006 Guangzhou, China Hong Wu, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, 510642 Guangzhou, China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Short- and long-term growth responses to drought and climatic influences still remain poorly understood. In this study, we investigated the impact of climatic drivers (temperature, precipitation) and drought, using the Standardized Precipitation Index (SPI) calculated at different time scales (1–48 months), on earlywood (EW) and latewood (LW) widths in Pinus halepensis. Nine forests subjected to dry summer conditions were sampled in Mediterranean semi-arid areas from north-eastern Spain. In addition, we explored the seasonal dynamics of cambial activity and wood formation in relation to short-term climate variability. We found two peaks of tracheid cell production corresponding to EW (May – June) and LW (mid-July–August) growth phases, associated with a sharp decrease in enlarging cells in early July in response to low water availability. In the period of analysis (1970–2005), EW growth was positively correlated with precipitation in previous December and current January, April, May and June, while it was negatively correlated with temperature in June and July. LW was correlated positively with minimum temperatures in January. Probably this was an indirect relationship as a consequence of increased EW width at higher January temperatures. Drought affected more negatively EW than LW formation as evidenced the higher SPI-EW correlation ( r  = 0.72) than the SPI-LW one ( r  = 0.54). The strongest EW response to drought was observed in July, whereas the highest LW response to drought occurred in September; and this seasonal pattern matched the phases of lowest EW and LW tracheid production. Under a future reduction of winter and spring precipitation, the studied forests may show a decrease in tracheid cell production, causing a decline of radial growth, a reduction in hydraulic conductivity and, indirectly, a hampered carbon uptake in such semi-arid woodlands. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0756-x Authors Edmond Pasho, Faculty of Forestry Sciences, Agricultural University of Tirana, 1029, Kodër-Kamëz, Tirana, Albania J. Julio Camarero, ARAID-Instituto Pirenaico de Ecología (CSIC), Avda. Montañana 1005, Zaragoza, 50080 Spain Sergio M. Vicente-Serrano, Instituto Pirenaico de Ecología (CSIC), Avda. Montañana 1005, Zaragoza, 50080 Spain Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Genetic variability and population structure of Sapindus trifoliatus L. (Sapindaceae), collected from Gujarat, Karnataka and Uttar Pradesh states were estimated using three DNA fingerprinting methods viz., random amplified polymorphic DNA (RAPD), directed amplification of minisatellite DNA (DAMD) and inter-simple sequence repeats (ISSR). The cumulative data analysis carried out for all three markers showed 69.42 % polymorphism. The intra-population genetic diversity analysis revealed the highest values of Nei’s genetic diversity (0.16), Shannon information index (0.24) and polymorphic loci (43.99 %) among Bhavnagar (BH) population, whereas lowest values were found in Junagarh (JU) population. The maximum inter-population average genetic distance (0.20) was between Allahabad (AL) and JU populations. Analysis of molecular variance (AMOVA) showed highest percentage of variation among individuals of populations (56 %) followed by 25 % among populations and 19 % among regions. Principal coordinate analysis and UPGMA dendrogram revealed that genetic diversity was in congruence with the geographical diversity. The data strongly suggest that low genetic flow, geographic isolation and to some extent genetic drift are the major factors responsible for high genetic differentiation. Preservation of genetic diversity of S. trifoliatus is important, both to promote adaptability of the populations to changing environment as well as to preserve a large gene pool for future genetic improvement. The present study using RAPD, DAMD and ISSR profiles of S. trifoliatus provide the means of rapid characterization of accessions within the populations, and thus enable the selection of appropriate accessions for further utilization in conservation and prospection programs of this important plant genetic resource. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0770-z Authors Kamalesh Singh Mahar, Molecular Systematics, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226 001 Uttar Pradesh, India Tikam Singh Rana, Molecular Systematics, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226 001 Uttar Pradesh, India Shirish Anand Ranade, Plant Molecular Biology (Genomics) Laboratory, CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226 001 Uttar Pradesh, India Veena Pande, Department of Biotechnology, Kumaun University, Bhimtal, Nainital, 263 136 Uttarakhand, India Lok Man Singh Palni, G. B. Pant Institute of Himalayan Environment and Development, Kosi-Katarmal, Almora, 263 643 Uttarakhand, India Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Scientists have discussed the halophytic nature of intertidal plants for decades, and have generally suggested that inherent differentiation of an obligate halophyte from a facultative halophyte relates strongly to whether the plant can survive in fresh water, and not much else. In this mini-review, we provide additional insight to support the pervasive notion that mangroves as a group are truly facultative halophytes, and thus add discourse to the alternate view that mangroves have an obligate salinity requirement. Indeed, growth and physiological optima are realized at moderate salinity concentrations in mangroves, but we maintain the notion that current evidence suggests that survival is not dependent upon a physiological requirement for salt. Content Type Journal Article Category Review Pages 1-5 DOI 10.1007/s00468-012-0767-7 Authors Ken W. Krauss, US Geological Survey, National Wetlands Research Center, 700 Cajundome Blvd, Lafayette, LA 70506, USA Marilyn C. Ball, Division of Plant Sciences, Research School of Biology, College of Medicine, Biology and Environment, Australian National University, The RN Robertson Bldg. (#46), Biology Place, Canberra, ACT 0200, Australia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Research related to the allometric relationships of tree height and projected tree crown area to diameter at breast height was conducted to look at the biological suitability and timber production potential of Douglas fir under the conditions present in central Europe. The dependence of allometric relationships on soil nutrient conditions were described in forest stands of Douglas fir and Norway spruce. The studied sites were climatically similar but differed in soil nutrient availability. A significant difference was found in the allometric relationships of Norway spruce trees from the nutrient poor and nutrient rich site. In contrast to the Norway spruce, there was no significant effect of site fertility on allometric relationships for Douglas fir suggesting that its allocation patterns were less sensitive to site nutrient conditions. Stem growth increment, which was measured weekly during two consecutive seasons for both species, was related to the weather conditions and available soil moisture. Stem growth of Douglas fir began about 2 weeks earlier than in the Norway spruce at both sites. At the nutrient rich site, most of the stem growth of both species occurred at the beginning of the season, while growth at the other site was more evenly distributed throughout the season. Data obtained in this study will be useful for modeling stem growth and analysis of water use efficiency of these two tree species. Content Type Journal Article Category Original Paper Pages 1-14 DOI 10.1007/s00468-012-0771-y Authors Josef Urban, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, Brno, 613 00 Czech Republic Kateřina Holušová, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, Brno, 613 00 Czech Republic Ladislav Menšík, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, Brno, 613 00 Czech Republic Jan Čermák, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, Brno, 613 00 Czech Republic Petr Kantor, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, Brno, 613 00 Czech Republic Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description: Erratum to: Real time qPCR expression analysis of some stress related genes in leaf tissue of Pyrus communis cv. Conférence after infection with Erwinia amylovora Content Type Journal Article Category Erratum Pages 1-2 DOI 10.1007/s00468-012-0751-2 Authors K. Vrancken, Molecular and Physical Plant Physiology, Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium H. Schoofs, Pomology Department, PC Fruit Research Station, Fruittuinweg 1, 3800 Sint-Truiden, Belgium T. Deckers, Pomology Department, PC Fruit Research Station, Fruittuinweg 1, 3800 Sint-Truiden, Belgium R. Valcke, Molecular and Physical Plant Physiology, Hasselt University, Agoralaan Building D, 3590 Diepenbeek, Belgium Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Pinus massoniana Lamb., a widely distributed coniferous species, is of ecologically and economically high value in southern China. However, it suffers serious damage from acid rain in recent decades. In order to gain a better understanding of the responses of P. massoniana to acid rain at the proteome level, a comparative proteomic study combined with physiological analyses between control and acid rain treatment was conducted. Among the over 1,000 protein spots detected reproducibly on the gel, we successfully identified 41 differentially expressed proteins, including 20 acid rain down-regulated proteins and 21 up-regulated proteins. The identified proteins were classified into five functional categories according to their biological functions. Among them, the photosynthesis and amino acid metabolism related proteins were greatly down-regulated, indicating the serious damages caused by acid rain in P. massoniana . By contrast, some energy- and defense-related proteins were dramatically up-regulated under acid rain, including proteins involved in tricarboxylic acid cycle (TCA), protein stability as well as those related to antioxidant system, suggesting that a variety of metabolic pathways were affected by acid rain. In particular, the expression of several proteins involved in secondary metabolism was also increased under acid rain stress, implying that the activated secondary metabolism plays an important role in the response of P. massoniana to acid rain. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0750-3 Authors Ting-Wu Liu, Key Laboratory for Coastal and Wetland Ecosystem of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, 361005 Fujian, People’s Republic of China Wen-Jun Hu, Key Laboratory for Coastal and Wetland Ecosystem of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, 361005 Fujian, People’s Republic of China Xiao-Qin Wang, Key Laboratory for Coastal and Wetland Ecosystem of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, 361005 Fujian, People’s Republic of China Li Niu, Key Laboratory for Coastal and Wetland Ecosystem of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, 361005 Fujian, People’s Republic of China Bin Fu, Key Laboratory for Coastal and Wetland Ecosystem of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, 361005 Fujian, People’s Republic of China Fei-Hua Wu, Key Laboratory for Coastal and Wetland Ecosystem of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, 361005 Fujian, People’s Republic of China Zhen-Ming Pei, Department of Biology, Duke University, Durham, NC 27708, USA Hai-Lei Zheng, Key Laboratory for Coastal and Wetland Ecosystem of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, 361005 Fujian, People’s Republic of China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Eucalyptus polybractea R.T. Baker is the key species used in Australia to produce commercial quantities of pharmaceutical-grade eucalyptus oil. Much of the variability in oil yield observed in coppiced stands of the species is considered genetically determined. Nonetheless it is not known how genetics acts on leaf and secretory cavity morphology to influence oil yield. To examine this, we first chose similar-sized mature leaves of different genotypes and determined that secretory cavity size accounted for 84 % of the variation in oil yield between genotypes. We then examined natural variation in mature leaf size found along branches and observed oil yield to increase in a linear, but non-proportional fashion with increasing leaf size, suggesting leaves of different final sizes on a given tree can have different volumetric oil proportions. From these analyses, we calculated that a minimum of 2.2 μl of photosynthetic tissue is required to service each additional μl of secretory cavities as leaves expand. This suggests there is likely to be a maximum oil concentration obtainable in E. polybractea leaves for a given leaf size increase. Such information helps to understand the factors that underlie oil yields and provides a potential framework for selection strategies aimed at maximising harvestable oil yields. Content Type Journal Article Category Short Communication Pages 1-6 DOI 10.1007/s00468-012-0744-1 Authors Jason Q. D. Goodger, School of Botany, The University of Melbourne, Parkville, VIC 3010, Australia Ian E. Woodrow, School of Botany, The University of Melbourne, Parkville, VIC 3010, Australia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    X-ray scattering and microtomography (μCT) are useful techniques to reveal the structure of wood at the nano- and micrometer scales. The nanostructure of xylem in greenhouse-grown 2.5- to 3.5-month-old Populus tremula L. ×  tremuloides Michx. trees was characterized using wide-angle X-ray scattering (WAXS), and the cellular structure was investigated using μCT. For comparison, the nanostructure of wood in 2-year-old silver birch, Norway spruce and Scots pine saplings was determined. Based on the μCT results, the lengths of fiber lumina of the hybrid aspen saplings were shorter than any previous results on the lengths of wood fibers. The mean microfibril angles of the hybrid aspen saplings were significantly lower (8°–14°) than those of the birch, spruce and pine saplings (27°–35°) implicating that cellulose microfibrils were oriented nearly parallel to the cell axis in the young hybrid aspen saplings. Hybrid aspen saplings were found to contain tension wood based on the histochemical analysis and μCT images. However, typical tension wood properties, i.e. larger crystallite width and higher crystallinity than in normal wood, were detected only in a few hybrid aspen samples, while in most of the hybrid aspen saplings, the crystallite widths (3.0 ± 0.1 nm) and the crystallinities (30 ± 5 %) corresponded to those of normal wood. The deformations of cellulose crystallites were determined using WAXS in situ upon dehydration of the never-dried samples. In all the species studied, the cellulose unit cell dimension decreased and disorder of cellulose chains increased parallel to the chains upon drying. Also, the transverse disorder of chains increased in birch, spruce and pine, while no changes were detected in this direction in hybrid aspen. The crystallite widths and drying deformation results might indicate that the gelatinous layer has not fully developed in the young hybrid aspen saplings. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0748-x Authors Kirsi Svedström, Department of Physics, University of Helsinki, P.O.B. 64, 00014 University of Helsinki, Finland Jessica Lucenius, Department of Physics, University of Helsinki, P.O.B. 64, 00014 University of Helsinki, Finland Jan Van den Bulcke, UGCT-WOODLAB, Department of Forest and Water Management, Ghent University, Coupure Links 653, 9000 Ghent, Belgium Denis Van Loo, UGCT, Department of Physics and Astronomy, Ghent University, Proeftuinstraat 86, 9000 Ghent, Belgium Peter Immerzeel, Department of Forest Genetics and Plant Physiology, SLU, Umeå Plant Science Centre, 90183 Umeå, Sweden Jussi-Petteri Suuronen, Department of Physics, University of Helsinki, P.O.B. 64, 00014 University of Helsinki, Finland Loes Brabant, UGCT, Department of Physics and Astronomy, Ghent University, Proeftuinstraat 86, 9000 Ghent, Belgium Joris Van Acker, UGCT-WOODLAB, Department of Forest and Water Management, Ghent University, Coupure Links 653, 9000 Ghent, Belgium Pekka Saranpää, Finnish Forest Research Institute, P.O.B. 18, 01301 Vantaa, Finland Kurt Fagerstedt, Department of Biosciences, University of Helsinki, P.O.B. 65, 00014 University of Helsinki, Finland Ewa Mellerowicz, Department of Forest Genetics and Plant Physiology, SLU, Umeå Plant Science Centre, 90183 Umeå, Sweden Ritva Serimaa, Department of Physics, University of Helsinki, P.O.B. 64, 00014 University of Helsinki, Finland Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Vertical leaf distribution and relative irradiance were ascertained for the dominant species Ulmus laevis Pall. at the level of the individual tree and at the level of the stand in a mixed broad-leaved forest in South Moravia, the Czech Republic. The study consisted of detailed, destructive measurement of five selected sample trees and the establishment of basic biometric parameters for the entire stand. Using allometric relationships, measurements from sample trees were generalized to diameter at breast height (DBH) classes and were then scaled up to the level of the imaginary pure stand of elm; the selected independent variables were tree height and DBH. The vertical leaf distribution was unimodal in trees with smaller dimensions and bimodal in trees with larger dimensions. The leaf area index (LAI) of the stand was 4 (6.4 including the undergrowth), and the sunlit leaf area index (SLAI) was 1.7. Dominant trees had a higher proportion of sunlit leaf area than subdominant and suppressed trees. Determination of appropriate methods and intensity of thinning can lead to optimizing of irradiation control, vitality increase of the elm stands and subsequently to a higher resistance to Dutch elm disease vector and disease itself. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0747-y Authors Martin Šrámek, Institute of Forest Botany, Dendrology and Geobiocenology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech Republic Jan Čermák, Institute of Forest Botany, Dendrology and Geobiocenology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech Republic Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Palaeoclimate proxies have demonstrated links between climate changes and volcanic activity. However, not much is known about the impact of volcanic eruptions on forest productivity. Here we used tree-ring width and annually resolved carbon and oxygen isotopic records from tree rings of Araucaria araucana (Molina) K. Koch, providing a centennial-scale reconstruction of tree ecophysiological processes in forest stands nearby the Lonquimay Volcano (Chile). We observed a mean decrease in tree-ring width following the major eruption of 1988 – 1990 (with aerosol emission), most probably caused by the modified ecological conditions due to acid rain and ash deposition, while a generally negative relationship between δ 13 C and δ 18 O would point to a decline in humidity and precipitation. More negative δ 13 C and lower δ 18 O values (positive correlation) following the major eruption of 1887–1890 (without aerosol emission) would suggest high stomatal conductance and moisture availability, though tree-ring width (and probably photosynthetic rate) was unaltered. At least for this sample of trees, in the case of eruption with large tephra emission, the beneficial effect of aerosol light scattering on tree productivity appears to be outweighed by the detrimental effect of eruption-induced toxic deposition. Signals of the two major eruptions of the past 200 years at Lonquimay were present in tree rings of nearby A. araucana . No unique response of tree functions to volcanic eruptions can be expected, but rather (1) the variable volcanic properties and (2) the complex interplay of diffuse light increase (aerosol scattering), air temperature decrease (cloud shading), and toxic deposition impact (volcanic ash), makes any prediction of tree growth and ecophysiological response very challenging. Content Type Journal Article Category Original Paper Pages 1-15 DOI 10.1007/s00468-012-0749-9 Authors Roberto Tognetti, Dipartimento di Bioscienze e Territorio, Università degli Studi del Molise, Contrada Fonte Lappone, 86090 Pesche, Italy Fabio Lombardi, Dipartimento di Bioscienze e Territorio, Università degli Studi del Molise, Contrada Fonte Lappone, 86090 Pesche, Italy Bruno Lasserre, Dipartimento di Bioscienze e Territorio, Università degli Studi del Molise, Contrada Fonte Lappone, 86090 Pesche, Italy Giovanna Battipaglia, Dipartimento di Scienze Ambientali, Seconda Università di Napoli, Via Vivaldi, 81100 Caserta, Italy Matthias Saurer, PSI, Paul Scherrer Institut, 5232 Villigen, Switzerland Paolo Cherubini, WSL, Swiss Federal Institute for Forest, Snow and Landscape Research, 8903 Birmensdorf, Switzerland Marco Marchetti, Dipartimento di Bioscienze e Territorio, Università degli Studi del Molise, Contrada Fonte Lappone, 86090 Pesche, Italy Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Theories that incorporate the area-preserving rule of Leonardo da Vinci predict that the sum of the cross-sectional lumen area of xylem conduits (vessels or tracheids) is constant across different levels of branching. If true, this rule obtains the packing rule, according to which (1) vessel cross-sectional lumen area ( A ) will negatively and isometrically scale to vessel number per unit area ( N ) and (2) the distal to proximal vessel diameter ratio (DR =  D n +1 / D n ) should scale as the −1/2 power of the distal to proximal vessel number ratio (NR =  N n +1 / N n ), i.e., DR = NR −1/2 . Using data collected from the terminal twigs and the petioles of 60 temperate (27 evergreen and 33 deciduous) woody species from southwestern China, we determined the scaling relationships for A versus N and for DR versus NR. Analyses of the data revealed contrasting scaling exponents and normalization constants for A versus N and for DR versus NR and no consistent trend across the two species groupings or between the two organ types (as predicted by the area-preserving and packing rules). These results caution against applying these rules ubiquitously to all species or to different organ types (even on the same plant). Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0742-3 Authors Hong Chen, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, Southwest University, Chongqing, 400715 China Karl J. Niklas, Department of Plant Biology, Cornell University, Ithaca, NY 14850, USA Shucun Sun, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Droughts are a cyclical disturbance in Mediterranean ecosystems and climate change models forecast an increase of their frequency and severity. Some experimental and observational studies have shown that co-occurring species may cope with drier conditions with different strategies and present different responses. Here, we investigate sap flow response to drought in order to explain the observed differential growth and mortality of Quercus ilex and Phillyrea latifolia at Prades Holm oak forest (NE Spain). We measured sap flow of these species and compared their diurnal, nocturnal and seasonal patterns and their relationship with environmental variables. Both species described qualitatively similar daily patterns, either during daylight or night. Sap flow rates were significantly higher in P. latifolia except in autumn and spring. P. latifolia was more sensitive to soil moisture. Nocturnal sap flow was detected in both species with no significant differences and hourly rates suffered a progressive increase from 3 a.m. to dawn in most sampled nights. Our results indicate a better adaptation of P. latifolia to this site as it can take better advantage of wet periods while maintaining higher sap flow rates during dry periods. Along with previous ecophysiological studies at the same location it may be inferred that at its drier distributional limit Q. ilex would be at disadvantage with respect to other species like P. latifolia , as the latter would cope better with increasing xeric conditions already occurring and further predicted for Mediterranean ecosystems. Our results also show nocturnal sap flow to be relevant in individual water losses in these two species as they can be up to 35–40 % of daily sap flow. Further research on the underlying mechanisms of this nocturnal sap flow is required since it may also enhance early morning CO 2 fixation or nutrient supply to leaves. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0741-4 Authors Adrià Barbeta, CREAF, Cerdanyola del vallès, 08193 Catalonia, Spain Romà Ogaya, CREAF, Cerdanyola del vallès, 08193 Catalonia, Spain Josep Peñuelas, CREAF, Cerdanyola del vallès, 08193 Catalonia, Spain Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    The aim of this study was to clarify the capability of Scots pine seeds ( Pinus sylvestris L.) of different origins to germinate and survive under waterlogging conditions. Seeds were used from one Spanish and three UK sources. All experiments were carried out in the glasshouse and under the optimum conditions for Scots pine seed to germinate and establish. A technique using inner and outer pots was used to produce four depths of waterlogging below the soil surface. Seed mass and viability were examined prior to use in the experiments. Waterlogging reduced germination, but an increase in time between sowing and waterlogging of up to 3 weeks and a watertable 〉4 cm below the surface greatly improved germination and seedling growth. Once established, seedling survival was remarkably tolerant of waterlogging, and seedlings survived 25 months even with the watertable at the soil surface. Seeds collected from trees on a floating bog in the English Midlands were least affected by waterlogging, but the variation among seed sources was small compared to the effects of the timing, depth and duration of waterlogging. Management implications are discussed. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0740-5 Authors Tarek A. Mukassabi, School of Life Sciences, Keele University, Huxley Building, Staffordshire, ST5 5BG UK Anthony Polwart, School of Life Sciences, Keele University, Huxley Building, Staffordshire, ST5 5BG UK Tim Coleshaw, Natural England, Attingham Park, Shrewsbury, UK Peter A. Thomas, School of Life Sciences, Keele University, Huxley Building, Staffordshire, ST5 5BG UK Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    There has been growing recent interest in the adaptations of tree species to seedling establishment in active northern temperate floodplains. In the case of Populus and Salix , most or all of the recent papers overlook a scattered, earlier literature showing that, in many Populus and Salix species, just after germination, the collet produces prominent hairs which, in young seedlings, may play an important role in anchorage and water absorption, the collet being the transition zone between the hypocotyl and the radicle. This earlier literature is briefly reviewed. The significance of collet hairs is then related to the very high seedling mortalities in riparian systems caused by high river flows (scour) or by drought stress arising from water level declines and coarse sediment textures. The need for work to establish just which species have collet hairs and to quantify the effect of collet hairs on anchorage and water absorption is emphasized. Content Type Journal Article Category Review Pages 1-5 DOI 10.1007/s00468-012-0738-z Authors R. F. Parsons, Department of Botany, La Trobe University, Bundoora, Victoria, 3086 Australia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    The New York Pine Plains are a unique ecosystem with normal statured and a dwarfed variety of pitch pines ( Pinus rigida Mill.). Growing interspersed with the dwarf pines are trees of intermediate height and features. Several hypotheses have been put forward as to why some of the trees are dwarfed, but none have been substantiated. In this study, we tested whether dwarf or medium trees are hydraulically limited compared to normally growing trees. Granier style sap flux sensors were installed in three to six trees of each tree type and sap flux was measured in early August 2004. Sap flux measurements were scaled to crown stomatal conductance using leaf area to sapwood area ratios for each tree. Contrary to expectation, dwarf and medium stature trees had very low leaf area to sapwood area ratios, but high crown stomatal conductances compared to normal trees. Analyses of leaf area, ring widths, and crown stomatal conductance indicate that differences between normal, and dwarf and medium pines are not due to hydraulic limitation, but that stunted growth may be due to other causes. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0736-1 Authors D. W. Vanderklein, Department of Biology and Molecular Biology, Montclair State University, Science Hall 116, Montclair, NJ 07043, USA K. V. R. Schäfer, Department of Biological Sciences, Rutgers University, 195 University Ave., Newark, NJ 07102, USA J. Martinez-Vilalta, CREAF, 08193 Cerdanyola del Vallès, Spain Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Wood density is an important plant trait that influences a range of ecological processes, including resistance to damage and growth rates. Wood density is highly dependent on anatomical characteristics associated with the conductive tissue of trees (xylem and phloem) and the fibre matrix in which they occur. Here, we investigated variation in the wood density of the widespread mangrove species Avicennia marina in the Exmouth Gulf in Western Australia and in the Firth of Thames in New Zealand. We assessed how variation in xylem vessel size, fibre wall thickness and proportion of phloem within the wood contributed to variation in wood density and how these characteristics were linked to growth rates. We found the wood density of A. marina to be higher in Western Australia than in New Zealand and to be higher in taller seaward fringing trees than in scrub trees growing high in the intertidal. At the cellular level, high wood density was associated with large xylem vessels and thick fibre walls. Additionally, wood density increased with decreasing proportions of phloem per growth layer of wood. Tree growth rates were positively correlated with xylem vessel size and wood density. We conclude that A. marina can have large xylem vessel sizes and high growth rates while still maintaining high wood density because of the abundance and thickness of fibres in which vessels are found. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0729-0 Authors Nadia S. Santini, The School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia Nele Schmitz, General Botany and Nature Management, Vrije Universiteit Brussel, Brussels, Belgium Catherine E. Lovelock, The School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Foliage dynamics of three functional tree types representing major components of the tropical montane evergreen forest in southern part of Central Ethiopia were compared. The species were Podocarpus falcatus (evergreen gymnosperm), Prunus africana (evergreen broadleaf), and Croton macrostachyus (facultative deciduous). The hypothesis examined is that in such tropical trees, endogenous control of foliage dynamics by the leaf life-spans (LLS) is largely dominant over external signals. Crown foliage turnover, leafiness of twigs, LLS, photosynthetic performance, respiration rate, specific leaf area, and relative growth rates of the stems were investigated. Foliage dynamics and leafiness of the twigs were monitored over 2 years while leaf traits were followed over 3 months. The degree of inter and intra-individual synchronization of foliage phenophases was examined to get an estimate of the contributions of endogenous and external signals to the dynamics of the foliages. Autoregression analysis indicated significant influence of the moisture regime on leaf sprouting of Croton and Podocarpus . During pronounced dry periods, new leaves were not developed. Analysis of phenological data using circular statistics revealed that in spite of strong inter-individual synchronization of leaf flush and fall ( Podocarpus and Croton ), the dynamics of individual parts of the crowns were less synchronized. LLS was independent of climate factors and it had substantial contribution to the control of foliage turnover. Moreover, examination of ecophysiological traits of developing leaves of the studied functional types showed differing patterns with LLS corroborating the ecophysiological characteristics. Although overlaid by fungal infestation, both the foliage and ecophysiological properties of Prunus resemble that of Podocarpus but the former exhibited a shorter LLS and slightly higher metabolic rates. Nevertheless, all species reacted positively to high moisture with respect to stem growth. In spite of largely differing weather conditions of the 2 years, direct competitive advantage of one of the species over the others could not be detected. Content Type Journal Article Category Original Paper Pages 1-18 DOI 10.1007/s00468-012-0723-6 Authors Yigremachew Seyoum, Department of Biology, Addis Ababa University, P.O. Box, 1176, Addis Ababa, Ethiopia Masresha Fetene, Department of Biology, Addis Ababa University, P.O. Box, 1176, Addis Ababa, Ethiopia Simone Strobl, Department of Plant Physiology and Bayreuth Centre for Ecology and Environmental Research (BAYCEER), University of Bayreuth, 95440 Bayreuth, Germany Erwin Beck, Department of Plant Physiology and Bayreuth Centre for Ecology and Environmental Research (BAYCEER), University of Bayreuth, 95440 Bayreuth, Germany Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Metallothioneins are Cys-rich, low-molecular weight, metal-binding proteins. In this paper, we aimed to evaluate the roles of type 2 metallothionein in Kandelia candel ( KcMT2 ) by analyzing its mRNA expression in leaves in response to heavy metals, as well as the metal-binding properties of its protein. The transcriptional response of KcMT2 gene to different heavy metals (Zn, Cu, Pb and Cd) was measured using real-time quantitative PCR. The results showed that the gene was regulated by the four metals tested. Significant increase in the expression of KcMT2 mRNA was also found in response to Zn, Cu, Pb and Cd. To analyze further the possible roles of KcMT2 against heavy metals, it was expressed in Escherichia coli BL21 as a carboxy-terminal extension of glutathione- S -transferase (GST). The E. coli cells expressing GST-KcMT2 fusion protein showed higher growth compared to the control cells under Zn, Cu, Pb or Cd exposure, and the GST-KcMT2 fusion protein had a stronger binding affinity for Zn, Cu, Pb and Cd than GST alone. Results presented here reveal that KcMT2 may play important roles in the heavy metal homeostasis or detoxification. Content Type Journal Article Category Original Paper Pages 1-8 DOI 10.1007/s00468-012-0727-2 Authors Guo-Yong Huang, Key Laboratory of Tropical Marine Environmental Dynamics, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China You-Shao Wang, Key Laboratory of Tropical Marine Environmental Dynamics, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China Guang-Guo Ying, State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640 China Ai-Cui Dang, Key Laboratory of Tropical Marine Environmental Dynamics, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Riparian ecotones in the fynbos biome of South Africa are heavily invaded by woody invasive alien species, which are known to reduce water supply to downstream environments. To explore whether variation in species-specific functional traits pertaining to drought-tolerance exist, we investigated wood anatomical traits of key native riparian species and the invasive Acacia mearnsii across different water availability proxies. Wood density, vessel resistance against implosion, vessel lumen diameter and vessel wall thickness were measured. Wood density varied significantly between species, with A. mearnsii having denser wood at sites in rivers with high discharge. As higher wood density is indicative of increased drought tolerance and typical of drier sites, this counter-intuitive finding suggests that increased wood density was more closely related to midday water stress, than streamflow quantity per se. Wood density was positively correlated with vessel resistance against implosion. Higher wood density may also be evidence that A. mearnsii is more resistant against drought-induced cavitation than the studied native species. The observed plastic response of A. mearnsii anatomical traits to variable water availability indicates the ability of this species to persist under various environmental conditions. A possible non-causal relationship between wood anatomy and drought tolerance in these riparian systems is discussed. Content Type Journal Article Category Original Paper Pages 1-10 DOI 10.1007/s00468-012-0726-3 Authors Casparus J. Crous, Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa Shayne M. Jacobs, Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa Karen J. Esler, Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    To fulfill the US Thanksgiving and Christmas tree markets, balsam fir ( Abies balsamea (L.) Mill.) is generally harvested before the cold season, anecdotally leading to premature needle senescence. Accordingly, we tested the hypothesis that LT exposure before harvest induces specific hormonal changes and delays postharvest senescence and/or abscission in balsam fir. Two hundred and six seedlings exposed to two temperature treatments for 48 h, LT at 5 °C and controls at 22 °C were severed off roots and monitored for their postharvest needle senescence. Root and shoot (needles and buds) tissues were examined for major endogenous hormone metabolites. LT increased shoot ABA (2,007 ng g −1 DW) by 2.5× and decreased GA 44 (9.84 ng g −1 DW) by 3.5× over those in roots. LT did not alter cytokinins, auxins or any root hormonal concentration. With auxins, only IAA, IAA-Asp, IAA-Leu and IAA-Glu were detected and the concentrations of IAA and IAA-Asp in shoots were lower than those found in roots. Among cytokinins, shoot c-ZR (58.95 ng g −1 DW) and t-ZR (4.17 ng g −1 DW) were 3× higher than those in roots. Apart from GA 44 , GA 9 (136.76 ng g −1 DW) was abundant in shoots. The PBL and PNL were 46 and 1.2 %, irrespective of treatments. LT seedlings held needles 11 days longer than the controls (122 days). In balsam fir, short-term LT exposure augmented ABA and decreased GA 44 levels in shoots and delayed postharvest needle senescence. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0728-1 Authors Arumugam Thiagarajan, Department of Environmental Sciences, Christmas Tree Research Center, Nova Scotia Agricultural College, Truro, NS B2N 5E3, Canada Rajasekaran Lada, Department of Environmental Sciences, Christmas Tree Research Center, Nova Scotia Agricultural College, Truro, NS B2N 5E3, Canada Steeve Pepin, Centre de recherche en horticulture, Université Laval, Quebec, QC G1V 0A6, Canada Charles Forney, Atlantic Food and Horticulture Research Centre, Agriculture and AgriFood Canada, Kentville, NS B4N 1J5, Canada Yves Desjardins, Centre de recherche en horticulture, Université Laval, Quebec, QC G1V 0A6, Canada Martine Dorais, Centre de recherche en horticulture, Université Laval, Quebec, QC G1V 0A6, Canada Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    During the last few years, considerable effort has been directed toward understanding how Eucalyptus globulus responds and adapts to low temperature due to its low freezing resistance, especially through gene expression analysis. A recent study has confirmed that freezing stress induces the expression of three dehydrin (DHN) genes in E. globulus . This work reports the identification of a new YSK-type DHN gene in E. globulus ( EuglDHN3 ) and examines the responses of this gene and the three previously reported ( EuglDHN1 , EuglDHN2 and EuglDHN10 ) under low temperature (LT), short photoperiod and water deficit (WD) in one sensitive and one freezing-resistant genotype of E. globulus , to assign them to a class: low temperature responsive, photoperiod responsive or water deficit responsive. Results indicated that two SK n -type DHNs ( EuglDHN1 and EuglDHN2 ) were strongly induced by LT and WD, the KS-type DHN ( EuglDHN10 ) was strongly induced by LT and the Y n SK n -type by WD. The expression patterns under LT and WD were consistent with the regulatory elements identified in the promoter regions of the four DHN genes. The differential accumulation of EuglDHN1 , EuglDHN2 and EuglDHN3 transcripts suggests a differential regulation in specific tissues under WD, and EuglDHN1 and EuglDHN10 under LT. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0722-7 Authors Marta Fernández, Faculty of Forest Sciences, University of Concepción, Concepcion, Chile Sofia Valenzuela, Faculty of Forest Sciences, University of Concepción, Concepcion, Chile Hita Barraza, Faculty of Forest Sciences, University of Concepción, Concepcion, Chile Javier Latorre, Faculty of Forest Sciences, University of Concepción, Concepcion, Chile Valeria Neira, Genomica Forestal S.A, Concepcion, Chile Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    The phenology of tree species in environments that are subject to strong climatic seasonality is mainly determined by water availability, which may vary as a function of wood density. The relationship among phenology, water potential, wood density and the capacity of water storage in the stem were determined for woody species of caatinga vegetation (dry forest) in the semiarid region of NE Brazil. Leaf flush and fall, flowering and fruiting events were recorded over a 31-month period, and the water potential was measured over a two-year period. These data were related to precipitation, water availability in the soil and photoperiod. Seven deciduous species exhibited low wood density (DLWD, 〈0.5 g cm −3 ), high capacity of water storage in the stem (until 250 % of the dry weight) and high water potential during the year, as opposed to 15 deciduous species that showed high wood density (DHWD, ≥0.5 g cm −3 ). Leaf flush, flowering and the fruiting of DHWD species were related to precipitation, whereas these phenological events occurred at the end of the dry season and/or the beginning of the rainy season for DLWD species and were related to the photoperiod. The two evergreen species showed variations of water potential that were intermediate between those of DHWD and DLWD deciduous species, leaf flush during the dry season and flowering at the end of dry season. These results suggest the existence of three functional groups: evergreen species, DHWD deciduous species and DLWD deciduous species. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0735-2 Authors André Luiz Alves de Lima, Universidade Federal Rural de Pernambuco (UFRPE), Unidade Acadêmica de Serra Talhada (UAST), Fazenda Saco s/n, Caixa Postal 063, 56900-000 Serra Talhada, Pernambuco, Brazil Everardo Valadares de Sá Barretto Sampaio, Centro de Tecnologia, Departamento de Energia Nuclear, Universidade Federal de Pernambuco (UFPE), Av. Prof. Luís Freire 1000, Cidade Universitária, 50740-540 Recife, Pernambuco, Brazil Cibele Cardoso de Castro, Universidade Federal Rural de Pernambuco, Unidade Acadêmica de Garanhuns, Avenida Bom Pastor, s/n-Boa Vista, 55296-901 Garanhuns, Pernambuco, Brazil Maria Jesus Nogueira Rodal, Departamento de Biologia/Área de Botânica, Universidade Federal Rural de Pernambuco (UFRPE), Rua Dom Manoel de Medeiros s/n, Dois Irmãos, 52171-900 Recife, Pernambuco, Brazil Antônio Celso Dantas Antonino, Centro de Tecnologia, Departamento de Energia Nuclear, Universidade Federal de Pernambuco (UFPE), Av. Prof. Luís Freire 1000, Cidade Universitária, 50740-540 Recife, Pernambuco, Brazil André Laurênio de Melo, Universidade Federal Rural de Pernambuco (UFRPE), Unidade Acadêmica de Serra Talhada (UAST), Fazenda Saco s/n, Caixa Postal 063, 56900-000 Serra Talhada, Pernambuco, Brazil Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Despite numerous studies on nitrogen (N) cycling in forest ecosystems, many uncertainties remain, particularly regarding long-term N accumulation in the soil. Models validated against tracer isotopic data from field labeling experiments provide a potential tool to better understand and simulate C and N interactions over multiple decades. In this study, we describe the adaptation of the dynamic process-based model TRACE to a new site, Alptal, where long-term N-addition and 15 N-tracer experiments provide unique datasets for testing the model. We describe model parameterization for this spruce forest, and then test the model with 9- and 14-year time series of 15 N-tracer recovery from control and N-amended catchments, respectively. Finally, we use the model to project the fate of ecosystem N accumulation over the next 70 years. Field 15 N recovery data show that the major sink for N deposition is the soil. On the control plot, tracer recovery in the soil increased from 32 % in the second year to 60 % in the ninth year following tracer addition, whereas on the N-saturated plot, soil recovery stayed almost constant from 63 % in the third year to 61 % in the twelfth year. Recovery in tree biomass increased over the decadal time scale in both treatments, to ca. 10 % over 9 years on the control plot and ca. 13 % over 14 years on the N-amended plot. We then used these time series to validate TRACE, showing that the adaptation and calibration procedure for the Alptal site was successful. Model-data comparison identified that the spreading method of 15 N tracers needs to be considered when interpreting recovery results from labeling studies. Furthermore, the ground vegetation layer was recognized to play an important role in controlling the rate at which deposited N enters soil pools. Our 70-year model simulation into the future underpinned by a Monte-Carlo sensitivity analysis, suggests that the soil is able to immobilize a constant fraction of 70 and 77 % of deposited N for the treated and the control plot, respectively. Further, the model showed that the simulated increased N deposition resulted in a relatively small elevated C sequestration in aggrading wood with an N use efficiency of approximately 7 kg C per kg N added. Content Type Journal Article Category Original Paper Pages 1-20 DOI 10.1007/s00468-012-0737-0 Authors Kim Krause, Swiss Fed. Inst. for Forest Snow and Landscape Research (WSL), 8903 Birmensdorf, Switzerland Isabelle Providoli, Centre for Development and Environment, University of Bern, 3012 Bern, Switzerland William S. Currie, School of Natural Resources and Environment, University of Michigan, Ann Arbor, USA Harald Bugmann, Forest Ecology, Swiss Fed. Inst. of Technology (ETH), 8092 Zurich, Switzerland Patrick Schleppi, Swiss Fed. Inst. for Forest Snow and Landscape Research (WSL), 8903 Birmensdorf, Switzerland Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Defoliation by herbivores may alter the source:sink balance of trees leading to transient decreases in carbon (C) stores. When C stores are replenished concurrently with re-growth both processes may compete, store formation proceeding at the expenses of growth. However, the interactions between both processes are not fully understood. We investigated the effects of defoliation by the pine processionary moth (PPM, Thaumetopoea pityocampa Dennis and Schiff.) on the non-structural carbohydrate (NSC) and nitrogen (N) stores and the growth of Pinus nigra Arnold trees. Short-term effects were evaluated immediately after a PPM outbreak and at the end of the first growing season in trees suffering a range of defoliation damage. Long-term effects were explored by a 17-year-long PPM defoliation experiment, with 11 years of repeated defoliation treatments followed by 6 years of recovery. Defoliation by PPM was followed by transient NSC decreases, but trees were able to exceed initial NSC pools and compensate growth in just one growing season. Such recovery was linked to increased foliage N. Repeated severe defoliations decreased growth and survival of trees in the long-term, but trees increased starch allocation to stems. Defoliation led to an accumulation of C storage compounds in P. nigra trees irrespective of their ability to re-grow. In trees included in the short-term experiment, the accumulation of stores proceeded concurrently with re-growth. However, the repeated severe defoliations included in our long-term experiment impaired the growth of trees, surplus C being accumulated as stores. These results indicate that, growth declines in pines defoliated by PPM are not due to C (source) limitation but may respond to the reduced sink strength of growing meristems due to defoliation, and thus, a decrease in C allocation to growth. Content Type Journal Article Category Original Paper Pages 1-14 DOI 10.1007/s00468-012-0739-y Authors Sara Palacio, Pyrenean Institute of Ecology (IPE-CSIC), Avda. Nuestra Sra. de la Victoria s/n Apdo. 64, 22700 Jaca, Huesca, Spain Rodolfo Hernández, Laboratorio de Sanidad Forestal, Servicio Provincial de Medio Ambiente de Teruel, Depto. Medio Ambiente, Gob. Aragón, C/Agustín Planas Sancho 10, 44400 Mora de Rubielos, Teruel, Spain Melchor Maestro-Martínez, Pyrenean Institute of Ecology (IPE-CSIC), Av. Montañana, 1005 Apdo. 13034, 50080 Zaragoza, Spain J. Julio Camarero, ARAID, Pyrenean Institute of Ecology (IPE-CSIC), Av. Montañana, 1005 Apdo. 13034, 50080 Zaragoza, Spain Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Belowground tree growth attributes determine whether associations will be complementary or competitive in an agroforestry context. A study on fine root ( d  ≤ 2 mm) distribution patterns of Dacryodes edulis based on root density (RD), root length density (RLD) and root weight density (RWD) was conducted to evaluate the effect of propagation methods on rooting distribution. Results showed that D. edulis trees of seed origin had greater RD ( P  ≤ 0.001) than trees of vegetative origin (cuttings and marcots) in the upper soil stratum (0–30 cm). Similarly, in the uppermost soil stratum (0–10 cm), RLD and RWDs varied significantly ( P  〈 0.01). Trees of seed origin had an exponential distribution pattern for fine RD, RLD and RWD with depth to 80 cm. In contrast, the distribution pattern of fine roots of trees of vegetative origin (cuttings and marcots) were quadratic for the same variables which increased in the 20–30 cm soil depth stratum before declining steadily to a depth of 80 cm. The findings of this study suggest that D. edulis trees of vegetative origin (cuttings and marots) are likely to be less competitive than trees of seed origin when intercropped with shallow-rooted annual plants in an agroforestry system for belowground resources. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0720-9 Authors E. K. Asaah, World Agroforestry Centre (ICRAF), West and Central Africa Regional Program, BP 16317, Yaounde, Cameroon T. N. Wanduku, The World Vegetable Center (AVRDC), Liaison Office Cameroon, Yaounde, Cameroon Z. Tchoundjeu, World Agroforestry Centre (ICRAF), West and Central Africa Regional Program, BP 16317, Yaounde, Cameroon L. Kouodiekong, World Agroforestry Centre (ICRAF), West and Central Africa Regional Program, BP 16317, Yaounde, Cameroon P. Van Damme, Faculty of Bioscience Engineering, University of Ghent, Ghent, Belgium Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    This review presents a new conceptual model for the involvement of low molecular flavanols in chromatin remodelling and genome organization. The experiments are based on the property of flavanols to associate with nuclei as revealed by blue staining after treatment with the p -dimethylaminocinnamaldehyde reagent. From a critical standpoint, this puzzling finding is nearly incompatible with current views about nuclear organization. Therefore, it was necessary to collect a whole host of data to confirm this new aspect and to gain some insight into possible regulatory roles of histone–flavanol assemblies. A lot of research has been devoted to this topic over the last 13 years. In particular, conifer nuclei were found to contain flavanols, whereas the nuclei of most angiospermous tree species investigated until now reacted negatively. Camellia sinensis (tea bush), being a broad-leaved dicotyledonous species indeed has nuclei with prominent flavanol staining. A subnuclear patterning of flavanols can be observed which is regulated by genetic and epigenetic mechanisms. Broadly speaking, flavanols of nuclei range from evenly diffuse to mosaic-like mottling and from pale to dark blue. The diffuse type is apparently characteristic of a more silenced nuclear state, whilst mild to prominent mottling implicates a transcriptionally more activated state. Dark blue flavanol blobs within the mottled mosaic state indicate a heterochromatin pattern whilst pale blue stippling tends to euchromatin. Environmental stress conditions such as drought combined with heat induce key signals for down-regulation of nuclear flavanols. In this article, various aspects of nuclear flavanol localization are summarized and discussed. Content Type Journal Article Category Review Pages 1-13 DOI 10.1007/s00468-012-0725-4 Authors Walter Feucht, Unit Fruit Science, Center of Life Sciences Weihenstephan, Technische Universität München, Dürnast 2, 85354 Freising, Germany Dieter Treutter, Unit Fruit Science, Center of Life Sciences Weihenstephan, Technische Universität München, Dürnast 2, 85354 Freising, Germany Jürgen Polster, Unit Physical Biochemistry, Centre of Life Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Citrus species are sensitive to an excess of boron (B). Currently, this toxicity is becoming a serious problem in the soils of arid and semi-arid environments throughout the world, where high concentrations of B may occur due to the agricultural use of wastewater. Citrus rootstocks can greatly influence the tolerance of citrus trees to different abiotic stresses. However, little is known about how the rootstock influences the tolerance of these trees to an excess of B. In this study, the effects of the nutrient solution’s B concentration (0.25, 2, 4.5 or 7 mg l −1 ) on the growth and other physiological, nutritional and biochemical parameters of Verna lemon trees that were grafted on four contrasting rootstocks [Carrizo citrange (CC), Cleopatra mandarin (CL), Citrus macrophylla (CM) and sour orange (SO)] were investigated. The plants were grown in a greenhouse in pots containing a universal substrate media and were watered daily with a Hoagland nutrient solution containing different concentrations of B. The results showed that the plant growth was progressively inhibited with an increasing concentration of B in the nutrient solution. However, the shoot was more sensitive to the B toxicity than were the roots. In addition, the growth inhibition was reduced in trees that were grafted on CL and CM when compared with those that were grafted on CC and SO. The concentration of B in the leaves, stems and roots also increased with an increase in the concentration of external B in the following order: leaves 〉 roots 〉 stem. The rootstock also had an influence on the B concentration in the different plant tissues. In the leaves, the B concentration was lowest in the plants that were grafted on the SO rootstock followed by the plants that were grafted on either the CM or CL rootstock and highest in the plants that were grafted on the CC rootstock. The net assimilation of CO 2 ( A \text CO 2 ) and the stomatal conductance ( g s ) leaf gas exchange parameters were reduced with an excess of B in the leaves, and this reduction was less pronounced for trees on CM and CL. The intercellular CO 2 concentration ( C i ) and the chlorophyll fluorescence indicated that the reduction of A \text CO 2 that was found with an excess of B was mainly due to non-stomatal factors. The mineral nutrition and organic solute data are also shown in this study. All of the data indicate that the tolerance to an excess of B is not related to the concentration of B that has accumulated in the leaves, which indicates that a combination of rootstock-dependent physiological, biochemical and anatomical responses determine the tolerance to an excess of B in citrus plants. Content Type Journal Article Category Original Paper Pages 1-14 DOI 10.1007/s00468-012-0724-5 Authors Vicente Gimeno, Centro de Edafología y Biología Aplicada del Segura, CSIC, Campus Universitario de Espinardo, 30100 Espinardo, (Murcia), Spain Inma Simón, EPSO (Univ. Miguel Hernández), Ctra. Beniel km 3,2, 03312 Orihuela, (Alicante), Spain Manuel Nieves, EPSO (Univ. Miguel Hernández), Ctra. Beniel km 3,2, 03312 Orihuela, (Alicante), Spain Vicente Martínez, Centro de Edafología y Biología Aplicada del Segura, CSIC, Campus Universitario de Espinardo, 30100 Espinardo, (Murcia), Spain José M. Cámara-Zapata, EPSO (Univ. Miguel Hernández), Ctra. Beniel km 3,2, 03312 Orihuela, (Alicante), Spain Antonio L. García, Facultad de Química, Universidad de Murcia.Campus Universitario de Espinardo, 30071 Espinardo, (Murcia), Spain Francisco García-Sánchez, Centro de Edafología y Biología Aplicada del Segura, CSIC, Campus Universitario de Espinardo, 30100 Espinardo, (Murcia), Spain Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Tropospheric ozone (O 3 ) is a critical threat to forest ecosystems. A stomatal flux-based risk evaluation methodology at the leaf level was established recently in the context of the Convention on Long-Range Transboundary Air Pollution (LRTAP). This study demonstrates improvement and validation of the stomatal flux-effect approach for adult beech with results from the 8-year free-air O 3 enrichment experiment at “Kranzberger Forst” (Germany). The risk assessment module of the SVAT model FO 3 REST, being under development for local scale O 3 -risk assessment of adult beech stands, was parameterized according to the LRTAP Convention’s Mapping Manual. Mean maximum stomatal conductance for water vapour of 245 mmol H 2 O m −2 PLA s −1 , as suggested in the LRTAP Convention’s Mapping Manual for beech, was affirmed by assessment at “Kranzberger Forst”, resulting in 162 mmol O 3 m −2 PLA s −1 upon recommended adjustment of the O 3 /water vapour diffusivity ratio to 0.663. Based on this ratio, a provisional corrected flux-effect function was deduced. Modelled Phytotoxic O 3 Doses ( POD 1 ) and potential O 3 -caused losses in biomass formation estimated with a site-specific stomatal conductance algorithm differed slightly only from estimates by the original LRTAP parameterisation. Analysis-derived POD 1 target value within the meaning of Article 2 of the European Council Directive 2008/50/EC of 10 mmol O 3 m −2 corresponded to potential loss in biomass formation of about 10 % in ambient air relative to “pre-industrial” conditions. However, exceedance occurred by about a factor of two during the study period, indicating high risk at “Kranzberger Forst” under ambient air. Assessment for doubled O 3 exposure indicated potential underestimation even of the O 3 risk because modelled losses in biomass formation are in the lower range of the standard deviation of the observed ones. Content Type Journal Article Category Original Paper Pages 1-9 DOI 10.1007/s00468-012-0716-5 Authors Ludger Grünhage, Department of Plant Ecology, Justus-Liebig University, Heinrich-Buff-Ring 26, 35392 Giessen, Germany Rainer Matyssek, Ecophysiology of Plants, Technische Universität München, Wissenschaftszentrum Weihenstephan, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany Karl-Heinz Häberle, Ecophysiology of Plants, Technische Universität München, Wissenschaftszentrum Weihenstephan, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany Gerhard Wieser, Division of Alpine Timberline Ecophysiology, Federal Research and Training Centre for Forests, Natural Hazards and Landscape, Rennweg 1, 6020 Innsbruck, Austria Ursula Metzger, Ecophysiology of Plants, Technische Universität München, Wissenschaftszentrum Weihenstephan, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany Michael Leuchner, Ecoclimatology, Technische Universität München, Wissenschaftszentrum Weihenstephan, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany Annette Menzel, Ecoclimatology, Technische Universität München, Wissenschaftszentrum Weihenstephan, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany Jochen Dieler, Forest Growth and Yield Science, Technische Universität München, Wissenschaftszentrum Weihenstephan, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany Hans Pretzsch, Forest Growth and Yield Science, Technische Universität München, Wissenschaftszentrum Weihenstephan, Hans-Carl-von-Carlowitz-Platz 2, 85354 Freising, Germany Winfried Grimmeisen, Bayerische Landesanstalt für Wald und Forstwirtschaft, Hans-Carl-von-Carlowitz-Platz 1, 85354 Freising, Germany Lothar Zimmermann, Bayerische Landesanstalt für Wald und Forstwirtschaft, Hans-Carl-von-Carlowitz-Platz 1, 85354 Freising, Germany Stephan Raspe, Bayerische Landesanstalt für Wald und Forstwirtschaft, Hans-Carl-von-Carlowitz-Platz 1, 85354 Freising, Germany Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Plasticity of biomass allocation is a key to growth and survival of trees exposed to variable levels of stress in their lifetime. Most of our understanding of dynamic biomass allocation comes from seedling studies, but plasticity may be different in mature trees. We used stem analysis to reconstruct whole-tree growth and biomass allocation patterns in Quercus pubescens trees harvested from a dry woodland in Valais, Switzerland. We identified three distinct growth phases. In phase I, a primary root developed but the aboveground structure did not persist. In phase II, height growth occurred and secondary roots developed. In phase III, height growth ceased and stems and roots only grew radially. Reference trees harvested from a less dry site nearby only showed phase II-type growth. In line with our hypothesis, drought-stressed trees maintained more biomass in roots and less in aboveground woody parts than reference trees. Contrary to our expectation, stressed trees allocated proportionally more resources to leaves and less to roots in the growing season before harvest than reference trees. It appears that sub-seasonal wood anatomical adjustments to water availability minimize hydraulic failure, thus enabling these dry woodland trees to invest preferentially in leaves. Wet years did not see preferential investment in aboveground tissues, suggesting more restricted plasticity in biomass allocation in these mature trees than in seedlings. It is concluded that trees beyond seedling stage show different responses to variation in drought than the better-studied seedlings. Content Type Journal Article Category Short Communication Pages 1-8 DOI 10.1007/s00468-012-0717-4 Authors Martijn Slot, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland Stijntje H. Janse-ten Klooster, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland Frank J. Sterck, Forest Ecology and Forest Management Group, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands Ute Sass-Klaassen, Forest Ecology and Forest Management Group, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands Roman Zweifel, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    A network of ten Faxon fir tree-ring width chronologies was constructed from sites ranging in elevation from 3,000 to 3,450 m in the Wolong Natural Reserve in Western Sichuan Province, China. The site chronologies display significant inter-site correlations (mean R  = 0.647, p  〈 0.001) and the first principal component (PC1) accounts for 68.32 % of the total variation of the chronologies, implying a high degree of similarity in growth variation among the elevation gradients. Correlation analysis using monthly climate data indicates that the radial growth response of Faxon fir along the elevation gradients is markedly similar to common climatic signals, such as sunshine duration (positive) and cloud cover (negative), from January to March. Thus, it appears that winter freezing stress, which is caused by low solar radiation and high cloudiness, is the major environmental factor regulating the growth of trees across the elevational gradients. In addition, the site chronologies have no elevation-dependent growth responses to temperature or precipitation. Irrespective of the elevational differences of the sample sites, an anomalous reduction in radial growth occurred consistently since the 1960s, diverging from the instrumental temperature records since the 1990s. The cause of this divergence may be ascribed to the recent accelerated winter freezing stress and its role in controlling radial growth. Content Type Journal Article Category Original Paper Pages 1-16 DOI 10.1007/s00468-012-0712-9 Authors Zong Shan Li, State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing, 100085 China Guo Hua Liu, State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing, 100085 China Bo Jie Fu, State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing, 100085 China Chan Juan Hu, State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing, 100085 China Shu Zheng Luo, State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing, 100085 China Xing Liang Liu, Institute of Ecology, Sichuan Forestry Research Academy, Chengdu, 610081 China Fei He, Institute of Ecology, Sichuan Forestry Research Academy, Chengdu, 610081 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Leaf chlorophyll fluorescence has been used to assess physiological stress effects in trees for at least 30 years. This paper describes a novel method for indicating tree vitality in Eucalyptus saligna Sm using bark chlorophyll fluorescence. A visual vitality index was successfully verified by comparing it with growth measurements such as total leaf area and above ground biomass. Bark and leaf chlorophyll fluorescence were then compared with the visual vitality index in spring, summer and autumn. The relationship between leaf chlorophyll fluorescence and the visual vitality index was weak, even with the one parameter that did show a relationship. There was good evidence for a statistical relationship between bark chlorophyll fluorescence and visual vitality, which may become a useful tool for tree vitality assessments in this species and possibly other tree species. Content Type Journal Article Category Original Paper Pages 1-12 DOI 10.1007/s00468-012-0730-7 Authors Denise Johnstone, Department of Resource Management and Geography, University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia Michael Tausz, Department of Forest and Ecosystem Science, University of Melbourne, Water Street, Creswick, VIC 3363, Australia Gregory Moore, Department of Resource Management and Geography, University of Melbourne, 500 Yarra Boulevard, Richmond, VIC 3121, Australia Marc Nicolas, Department Agriculture and Food Systems, University of Melbourne, Parkville, VIC 3010, Australia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    We determined the temporal and seasonal dynamics of intra-annual cell formation of south Florida slash pine ( Pinus elliottii Engelm. var. densa Little & Dor.), the southernmost native pine in the United States and the foundation species of globally endangered pine rockland ecosystems. To assess intra-annual cambial activity and identify possible relationships between cell production and climatic factors, wood micro-cores were extracted monthly from six trees during the period March 2010 to March 2011. The results confirmed annual growth ring formation in P . elliottii var. densa and indicated that its growing season extends from February to December, with a short period of dormancy that varied little between individuals. Within the growing season, earlywood cells were produced from February to July, latewood cells produced from July to December, and intra-annual density fluctuations (IADFs) occurred in the growth rings of four of six trees between July and August. A principal component analysis indicated a homogeneous response of cambial activity among trees to site-specific climatic factors. The first principal component axis explained 71 % of the total variance in cell production during the study period. Our results indicated that the dynamics of seasonal cambial activity of P . elliottii var. densa are controlled by solar radiation ( r  = 0.51, p  〈 0.10) in the Florida Keys. The nature of our data allow us to only speculate on the ecophysiological processes responsible for IADFs in P . elliottii var. densa , and additional research is needed to better understand the relationship between their formation and the environment in the Lower Florida Keys. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0719-2 Authors Grant L. Harley, Laboratory of Tree-Ring Science, Department of Geography, The University of Tennessee, 304 Burchfiel Geography Bldg, Knoxville, TN 37996-0925, USA Henri D. Grissino-Mayer, Laboratory of Tree-Ring Science, Department of Geography, The University of Tennessee, 304 Burchfiel Geography Bldg, Knoxville, TN 37996-0925, USA Jennifer A. Franklin, Department of Forestry, Wildlife, and Fisheries, The University of Tennessee, 274 Ellington Plant Sci. Bldg, Knoxville, TN 37996-4563, USA Chad Anderson, United States Fish and Wildlife Service, National Key Deer Refuge, Big Pine Key, 28950 Watson Blvd, Florida, 33043 USA Nesibe Köse, Department of Forest Botany, Istanbul University, 34473 Bahçeköy, Istanbul, Turkey Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Tree branches and stems have different physiological functions that work collaboratively to maximize light interception. Light penetration in tree crowns is controlled by the orientation of the branches. However, mechanisms of branch bending have not received the attention they deserve. This study approached the problem by investigating the growth strain distribution in the upper and lower sides of branches of broadleaf trees, estimating the bending tendency of branches, and observing the branch eccentricity and the distribution of gelatinous fibers. The strain distribution was compared between the branches of 11 species (including 8 examined species and 3 referenced species) and tilted stems of 37 species from both our data and previous reports. Compressive strain was generally observed on the lower side of branches, but little was measured in tilted stems. The pith eccentricity of branches was in a reverse pattern to the corresponding strain distribution of stems. The radial growth of branches was hypotropic in contrast to the epitropic eccentric growth in inclined trunks. Furthermore, on the upper side of branches, G-fibers within the fiber arcs formed in an intermittent manner rather than in the continual manner found in artificially inclined stems. The resultant upward bending moment might not suffice to counteract the branch’s own weight; therefore, most of the measured branches, differing from tilted stems, tended to bend downward. In conclusion, by comparing the biological and mechanical aspects of the strain distribution, bending tendency, and eccentricity, our experiments could discriminate the bending dynamics and role of G-fibers in tree branches from that of main stems. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0733-4 Authors Ching-Chu Tsai, Department of Life Science, National Taiwan University, 1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan Li-Fen Hung, Institute of Ecology and Evolutionary Biology, National Taiwan University, 1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan Ching-Te Chien, Division of Silviculture, Taiwan Forestry Research Institute, 53 Nanhai Rd., Taipei, 10066 Taiwan Shiang-Jiuun Chen, Department of Life Science, National Taiwan University, 1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan Yan-San Huang, Department of Forestry, National Chung Hsing University, 205, Kuokuang Rd., Taichung, 402 Taiwan Ling-Long Kuo-Huang, Department of Life Science, National Taiwan University, 1, Roosevelt Rd., Sec. 4, Taipei, 106 Taiwan Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Root tensile strength plays an important role in soil stabilization and fixation. Testing and separating the different factors that affect root tensile strength are important. In the present study, the effects of four factors, namely, gauge length, strain rate, species, and root diameter, on root tensile strength were studied. Uniaxial tensile tests were conducted to acquire the root tensile strength of five tree species commonly growing in the mountains of northern China, namely, Chinese pine ( Pinus tabulaeformis Carr.), Larch ( Larix principis - rupprechtii Mayr.), White birch ( Betula platyphylla Suk.), Mongolian oak ( Quercus mongolicus Fisch.), and Elm ( Ulmus pumila L.). Based on the results, Elm and White birch roots were the most resistant to tension, followed by Mongolian oak and Chinese pine roots. Larch roots were found to be the least resistant to tension. A power relationship was established between root diameter and root tensile strength. Based on linear regression analysis, gauge length was negatively correlated with root tensile strength. Tensile strength decreased with increasing gauge length. In addition, an unexpected variation of tensile strength was observed between two strain rates (10 and 400 mm min −1 ). The present study can serve as a basis for further studies on mechanical properties of root system and root reinforcement under different test circumstances, although this should be done with caution. Content Type Journal Article Category Original Paper Pages 1-8 DOI 10.1007/s00468-012-0732-5 Authors Chaobo Zhang, College of Water Resources Science and Engineering, Taiyuan University of Technology, 030024 Taiyuan, Shanxi, China Lihua Chen, Key Laboratory of Soil and Water Conservation and Combating Desertification of Ministry of Education of China, School of Water and Soil Conservation, Beijing Forestry University, 100083 Beijing, China Jing Jiang, College of Water Resources Science and Engineering, Taiyuan University of Technology, 030024 Taiyuan, Shanxi, China Shuo Zhou, Capital Engineering and Research Incorporation Ltd., MCC Group, 100053 Beijing, China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Measuring whole-plant transpiration is highly relevant considering the increasing interest in understanding and improving plant water use at the whole-plant level. We present an original software package (Amalthea) and a design to create a system for measuring transpiration using laboratory balances based on the readily available commodity hardware. The system is modular, capable of multiple-balance synchronisation and is highly scalable from one to one hundred units. The software runs under GNU/Linux and it requires little computer resources. Reporting of transpiration rates is based on the linear regressions of data from pre-set intervals which yields high resolution and provides some level of noise filtering. Using a scale with 0.01-g precision we have measured mean rates as low as 0.01 mmol s −1 over intervals of 220 s. Its flexibility accommodates varied applications, such as monitoring nighttime transpiration or long-term drought treatments and would be suitable for measuring a range of plants, from small herbs to potted trees. Content Type Journal Article Category Short Communication Pages 1-8 DOI 10.1007/s00468-012-0731-6 Authors Damián Cirelli, University of Alberta, Edmonton, AB, Canada Victor J. Lieffers, University of Alberta, Edmonton, AB, Canada Melvin T. Tyree, University of Alberta, Edmonton, AB, Canada Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Variation in the growth of Larix hybrid trees is under complex genetic regulation. To examine whether microRNAs (miRNAs) are involved in this complex regulation, we compared miRNA expression profiles between six fast- and six slow-growing Larix hybrid lines from two full-sib families. Five miRNAs were differentially expressed between the fast- and slow-growing lines, of which ppt-miR477g-3p, mml-miR-675 and smo-miR1083 were down-regulated, and cre-miR905* and vvi-miR171a were up-regulated in the six fast-growing lines. Analyses of the target genes of these five miRNAs revealed a common functional feature—changes in the expression of those miRNAs in the fast-growing trees can potentially lead to an enhanced cell proliferation and superior ability to adapt to environmental changes/stresses. Comparison of the expression profiles between families revealed a family specific expression signature—eight members of miR395 family were differentially expressed between the fast- and slow-growing trees in one full-sib family but not in another, suggesting a family dependent unique miRNA regulation. Differential miRNA expression was confirmed and independently validated by QRT-PCR. Orthologous miRNA hybridization between species was verified by sequencing some of the Larix miRNA. Taken together, our data suggested that rapid growth in Larix is subject to complex miRNA regulation. Some of the regulatory mechanisms are common among families while others are unique to a given family. Five differentially expressed miRNAs between the fast- and slow-growing trees may play a role in regulating growth of Larix trees. Content Type Journal Article Category Original Paper Pages 1-8 DOI 10.1007/s00468-012-0734-3 Authors Shougong Zhang, Laboratory of Cell Biology, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091 China Suying Han, Key Laboratory of Research Institute of Forest Ecology and Protection, Chinese Academy of Forestry, Beijing, 100091 China Wanfeng Li, Laboratory of Cell Biology, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091 China Jian Zhou, Department of Pathology and Laboratory Medicine, University of California at Los Angeles, 650 Charles Young Dr., Los Angeles, CA 90095, USA Xinmin Li, Department of Pathology and Laboratory Medicine, University of California at Los Angeles, 650 Charles Young Dr., Los Angeles, CA 90095, USA Liwang Qi, Laboratory of Cell Biology, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091 China Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Trees outside closed forest stands differ in the relation between stem diameter, height and crown volume from trees that grew with neighbours close by. Whether this plasticity in tree shape varies between species in relation to their light requirement is unknown. We purposefully sampled 528 trees ranging 5–100 cm diameter at breast height growing in a range of light conditions. Across ten broad-leaved species observed in Sumatra or Kalimantan, a generic relationship was found between light exposure of the crown and a light-dependent a l parameter that modifies the height–diameter allometric equation ( H  =  a l D b ) from those for closed stands. In our results, vertical stretching is well predicted by light availability. In fully open conditions, trees are on average 31% shorter for the same diameter than under (partial) shade. Most of the stretching response occurs in all species as soon as some degree of lateral shading occurs. The response, however, varies by species (8–44% reduction) in a way apparently unrelated to species’ successional status. Crown volume varied less than stem height in its relationship with stem diameter across all light conditions tested. The scaling of crown volume with stem diameter, however, differed markedly between tree species. Content Type Journal Article Category Original Paper Pages 1-11 DOI 10.1007/s00468-012-0703-x Authors Degi Harja, Southeast Asia Regional Program, World Agroforestry Centre (ICRAF), Jalan CIFOR, Situ Gede, Sindang Barang, Bogor, 16115 Jawa Barat, Indonesia Grégoire Vincent, Unité Mixte de Recherche AMAP, Institut de Recherche pour le Développement (IRD), TA A-51/PS2, 34398 Montpellier Cedex 5, France Rachmat Mulia, Southeast Asia Regional Program, World Agroforestry Centre (ICRAF), Jalan CIFOR, Situ Gede, Sindang Barang, Bogor, 16115 Jawa Barat, Indonesia Meine van Noordwijk, Southeast Asia Regional Program, World Agroforestry Centre (ICRAF), Jalan CIFOR, Situ Gede, Sindang Barang, Bogor, 16115 Jawa Barat, Indonesia Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description:    Insights into the physiology of nitrogen (N) uptake help us to understand the adaption of boreal coniferous forests to their environment. We compared fluxes of nitrate and ammonium in white spruce [ Picea glauca (Moench) Voss] roots, measured using a non-invasive microelectrode ion flux measurement system (MIFE), and transcript abundance of ammonium and nitrate transporter genes in roots, determined by real time PCR. Seedlings were pretreated with water, or 50 μM or 1,500 μM NH 4 NO 3  + 200 μM CaSO 4  + 25 μM KH 2 PO 4 . Measurements were made on seedling roots 0–5, 5–10, 10–20 and 20–30 mm from the root tip. As ammonium and nitrate transporter family members in spruce are still uncharacterized, primers for real time PCR were designed to cover one family with each set of primers (AMT1, AMT2, NRT1, NRT2). The expression patterns obtained by real time PCR differed significantly among transporter family, treatments and root segments. Expression of AMT1 did not show a relationship with distance from the root tip, but the expression of AMT2 was generally greater 0–5 mm from the root tip than in segments farther from the tip. Expression of NRT1 was greatest 10–30 mm from the root tip, while expression of NRT2 was greatest 5–10 mm from the tip in all treatments, except the 1,500 μM NH 4 NO 3 treatment. MIFE measurements showed the highest N uptake and proton efflux near the root tip and declining fluxes with increased distance from the root tip in the 50 μM N treatment. Significant net ammonium efflux was observed from some root segments in the 1,500 μM N treatment. Transporter gene expression and ion fluxes were not correlated. Though the measured net fluxes of ammonium were greater than the measured net fluxes of nitrate, the nitrate transporters were, in general, more highly expressed than the ammonium transporters. Content Type Journal Article Category Short Communication Pages 1-9 DOI 10.1007/s00468-012-0700-0 Authors A. Alber, Centre for Forest Biology, University of Victoria, P.O. Box 3020 STN CSC, Victoria, BC V8W 3N5, Canada B. Ehlting, Centre for Forest Biology, University of Victoria, P.O. Box 3020 STN CSC, Victoria, BC V8W 3N5, Canada J. Ehlting, Centre for Forest Biology, University of Victoria, P.O. Box 3020 STN CSC, Victoria, BC V8W 3N5, Canada B. J. Hawkins, Centre for Forest Biology, University of Victoria, P.O. Box 3020 STN CSC, Victoria, BC V8W 3N5, Canada H. Rennenberg, Chair of Tree Physiology, Institute of Forest Botany and Tree Physiology, University of Freiburg, Georges-Köhler-Allee, 53/54, 79085 Freiburg, Germany Journal Trees - Structure and Function Online ISSN 1432-2285 Print ISSN 0931-1890

Description: Key message This manuscript shows experimentally that light and temperature significantly influence the density and cellular features of the secretory spaces in C . langsdorffii , an economically important legume tree in Brazil. Abstract Copaifera langsdorffii is known for its production of terpenes, which are exploited by several industrial sectors. In this species, secretory cavities and canals are present in seedlings and adult plants and constitute an important defense mechanism against herbivores and pathogens. Evidence suggests that exogenous factors modify the production of secretions in this species; however, the influence of these factors on the secretory system structure is unknown. We investigated the effects of light and temperature on the density of secretory canals and cavities in C . langsdorffii seedlings, and the influence of temperature on the ultrastructure of the epithelial cells. Seedlings were maintained in different light intensities (460, 230, and 46 μmol m −2  s −1 ) and temperatures (15, 25, and 35 °C) in 3 × 3 combinations. The densities of secretory spaces in epicotyls and eophylls were calculated in cross sections under a light microscope. For ultrastructural studies, samples of eophylls were prepared following the conventional techniques of transmission electron microscopy. Seedlings at 25 °C/230 μmol m −2  s −1 and 25 °C/460 μmol m −2  s −1 showed increased density of cavities and canals, respectively, suggesting an improved protection of the plants in these conditions. Ultrastructurally, the epithelial cells of seedlings observed at 25 °C contained dense cytoplasm rich in organelles, indicating intense secretory activity. At 15 and 35 °C, seedlings showed morphological alterations in mitochondria, plastids, and endoplasmic reticulum. The epithelial cells presented signs of intense lysing at 35 °C, indicating impaired secretory activity. Our data proved that light and temperature can induce alterations in the secretory system of C. langsdorffii seedlings, suggesting changes to their defense system.

Description: Key message Carbon isotope ratios in growth rings of a tropical tree species show that treefall gaps stimulate diameter growth mainly through changes in the availability of light and not water. The formation of treefall gaps in closed canopy forests usually entails considerable increases in light and nutrient availability for remaining trees, as well as altered plant water availability, and is considered to play a key role in tree demography. The effects of gaps on tree growth are highly variable and while usually stimulatory they may also include growth reductions. In most studies, the causes of changes in tree growth rates after gap formation remain unknown. We used changes in carbon isotope 13 C discrimination (Δ 13 C) in annual growth rings to understand growth responses after gap formation of Peltogyne cf. heterophylla , in a moist forest of Northern Bolivia. We compared growth and Δ 13 C of the 7 years before and after gap formation. Forty-two trees of different sizes were studied, half of which grew close (〈10 m) to single treefall gaps (gap trees), the other half more than 40 m away from gaps (controls). We found variable responses among gap trees in growth and Δ 13 C. Increased growth was mainly associated with decreased Δ 13 C, suggesting that the growth response was driven by increased light availability, possibly in combination with improved nutrient availability. Most trees showing zero or negative growth change after gap formation had increased Δ 13 C, suggesting that increased water stress did not play a role, but rather that light conditions had not changed much or nutrient availability was insufficient to support increased growth. Combining growth rates with Δ 13 C proved to be a valuable tool to identify the causes of temporal variation in tree growth.