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  • Springer  (683,258)
  • Oxford University Press  (64,450)
  • American Geophysical Union  (40,436)
  • American Meteorological Society
  • 1995-1999  (399,361)
  • 1990-1994  (368,367)
  • 1935-1939  (35,312)
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  • 1
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    A new extended software package for quantitative paleoenvironmental reconstrutions (1999)
    American Geophysical Union
    In:  EPIC3EOS, Transactions of the American Geophysical Union, American Geophysical Union, 80(19), 223 p., pp. 223-223
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
    Format: application/zip
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  • 2
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    Gold metallogeny in the Sino-Korean Platform: examples from Hebei province, NE China. (1992)
    Springer
    Details
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/book
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  • 3
    Electronic Resource
    Electronic Resource
    Allometric analysis of Sitka spruce branches: mechanical versus hydraulic design principles (1995)
    Springer
    Trees 10 (1995), S. 1-12 
    Details
    ISSN: 1432-2285
    Keywords: Sitka spruce ; Geometry ; Allometry ; Branch form ; Architecture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The geometry of tree branches can have considerable effect on their efficiency in terms of carbon export per unit carbon investment in structure. The purpose of this study was to evaluate different design criteria using data describing the form of Picea sitchensis branches. Allometric analysis of the data suggests that resources are distributed to favour shoots with the greatest opportunity for extension into new space, with priority to the extension of the leader. The distribution of allometric relations of links (branch elements) was tested against two models: the pipe model, based on hydraulic transport requirements, and a static load model based on the requirement of shoots to provide mechanical resistance to static loads. Static load resistance required the load parameter to be proportional to the link radius raised to the power of 4. This was shown to be true within a 95% statistical confidence limit. The pipe model would require total distal length to be proportional to link radius squared but the measured branches did not conform well to this model. The comparison suggests that the diameters of branch elements were more related to the requirements for mechanical load. The cost of following a hydraulic design principle (the pipe model) in terms of mechanical efficiency was estimated and suggested that the pipe model branch would not be mechanically compromised but would use structural resources inefficiently. Resource allocation among branch elements was found to be consistent with mechanical stability criteria but also indicated the possibility of allocation based on other criteria, such as potential light interception by shoots. The evidence suggests that whilst branch topology increments by reiteration of units of morphogenesis, the geometry follows a functional design pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197773
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  • 4
    Electronic Resource
    Electronic Resource
    Anatomical studies of branchlet abscission related to crown modification in Quercus cerris L. (1995)
    Springer
    Trees 10 (1995), S. 20-23 
    Details
    ISSN: 1432-2285
    Keywords: Crown modification ; Oak decline ; Quercus cerris L ; Twig abscission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The basic anatomy of lateral twig insertion onto the main branch in both healthy and damaged Quercus cerris L. trees was studied. An abscission zone is always present: in healthy trees it is formed by a smaller number of cell layers than in damaged ones, where it is more evident with many layers of cells. Cells of the abscission zone are roundish, with many intercellular spaces between them; cell walls are thin, non-lignified and without secondary walls. No starch was found in cells of the abscission zone, where, instead, a few scattered calcium oxalate druses are seen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197775
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  • 5
    Electronic Resource
    Electronic Resource
    Stem annual increments as ecobiological indicators in Turkey oak (Quercus cerris L.) (1995)
    Springer
    Trees 10 (1995), S. 13-19 
    Details
    ISSN: 1432-2285
    Keywords: Volume increment ; Stem analysis ; Dendroclimatology ; Quercus cerris ; Southern Italy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In recent decades, the biostatistical analysis of relationships among tree growth and macroclimatic factors has developed remarkably. In this discipline, the parametrisation of tree growth is generally based on the records of annual ring widths measured on breast height transverse sections of tree stems (ARI). The present research enables the stem volume annual increment (AVI) to be evaluated as a dendroclimatic indicator in comparison with ARI. The research is a part of a broader investigation into the ecobiological characteristics of Turkey oak in the Gargano region (southern Italy). The results indicate that AVI is no better than ARI as a means of highlighting expressive relationships among the examined macroclimatic factors (monthly precipitation and monthly averages of temperature daily maxima and minima) and the Turkey oak annual stem growth. In the examined stands, the most growthinfluencing factors are the autumn and spring rainfalls. Regarding the stem breast height radial increment, the most effective temperature factors are the June averages of daily minima and maxima.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197774
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  • 6
    Electronic Resource
    Electronic Resource
    The concentration of Ca, Sr, Ba and Mn in successive needle age classes of Norway spruce [Picea abies (L.) Karst.] (1995)
    Springer
    Trees 10 (1995), S. 31-39 
    Details
    ISSN: 1432-2285
    Keywords: Calcium ; Barium ; Manganese ; Strontium ; Picea abies needles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The concentrations of Ca, Sr, Ba and Mn were determined in up to five successive needle age classes from 54 individual Norway spruce trees [Picea abies (L.) Karst] from nine different sites. The accumulation behaviour was found to be very nonuniform, going from an increase with needle age to a decrease; irregular patterns were also found. The type of accumulation is largely site specific. The increasing behaviour can in most cases be approximated by a simple arithmetic function. All four elements usually show the same accumulation pattern, the similarities being closest between Ca and Mn and least between Ca and Ba. It is postulated that the similarity between the four elements is due to their precipitation and storage as oxalates. The similarity between Ca, Sr and Ba is observed at all concentrations, that with Mn only at concentrations larger than 300 μg/g. Mn at small concentrations (〈 50 μg/g) shows a decreasing pattern and no similarity at all with Ca, Sr and Ba, but behaves similar to mobile elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197777
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  • 7
    Electronic Resource
    Electronic Resource
    Daily dynamics in xylem cell radial growth of Scots pine (Pinus sylvestris L.) (1995)
    Springer
    Trees 10 (1995), S. 24-30 
    Details
    ISSN: 1432-2285
    Keywords: Pinus sylvestris L. ; Wood formation ; Tracheid ; Radial cell expansion ; Daily growth dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Daily dynamics of radial cell expansion during wood formation within the stems of 25-year-old Scots pine trees (Pinus sylvestris L.), growing in field conditions, were studied. The samples of forming wood layers were extracted 4 times per day for 3 days. Possible variations in the growth on different sides of the stem, duration of cell development in radial cell expansion phase and dynamics of cell growth in this phase were taken into account. The perimeters of tracheid cross-sections as a reflection of primary cell wall growth were the criterion of growth in a radial direction. For the evaluation of growing cell perimeters a special system for digital processing and image analysis of tracheid cross-sections of the forming wood was used. Growth rate for certain time intervals was estimated by the change in the relation of the perimeter of each observed cell in each of ten tracheid rows in each of 12 trees to the perimeter of the xylem cell of the same row before the expansion. Temporal differences in average values of the relations were estimated by Analyses of Variance. The existence of daily dynamics of Scots pine xylem cell radial growth has been proved. Intensive growth of pine tracheids has been shown to occur at any time of the day and to depend on the temperature regime of the day and the night as well as water supply of stem tissues. Moreover, reliable differences (P = 0.95) in the increment of cell walls during tracheid radial expansion have been found. Pulsing changes of the water potentials both of the cell and the apoplast, as the reason for the fluctuations of radial cell growth rate, were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197776
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  • 8
    Electronic Resource
    Electronic Resource
    Quinate:NAP(P)+-oxidoreductase from Larix sibirica: purification, characterization and function (1995)
    Springer
    Trees 10 (1995), S. 46-51 
    Details
    ISSN: 1432-2285
    Keywords: Larix sibirica ; Metabolism ; Quinate:NAD(P)+-oxidoreductase ; Quinic acid ; Shikimate pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Quinate:NAP(P)+-oxidoreductase (QORase, EC 1.1.1.24), which catalyzes the interconversion of quinic and 3-dehydroquinic acids, was purified from the needles and developing xylem cells of Larix sibirica. The enzymes from these two tissues were partially characterized and compared. QORase from needles had optimum pH at 9.0 and apparent Km values of 1.84 mM for quinic acid and 0.19 mM for NADP+. The enzyme was activated by phosphoenolpyruvate. Gallic and protocatechuic acids were formed in a reaction mixture of purified enzyme from needles as final products of quinic acid transformation. QORase from developing xylem cells showed pH optimum at 10.0 and had apparent Km values of 0.70 mM for quinic acid and 0.05 mM for NADP+. The enzyme was not affected by PEP. The divalent cations Co2+ and Mn2+ at least doubled activity of QORase from both sources but Mg2+ affected the enzyme from needles only. The spatial organization and regulation of quinic acid metabolism in the autotrophic and heterotrophic cells of conifers and the role of QORase in this process are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197779
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  • 9
    Electronic Resource
    Electronic Resource
    Triacylglycerols in the seeds of northern Scots pine, Pinus sylvestris L., and Norway spruce, Picea abies (L.) Karst. (1995)
    Springer
    Trees 10 (1995), S. 40-45 
    Details
    ISSN: 1432-2285
    Keywords: Picea abies ; Pinus sylvestris ; Conifer seeds ; Fatty acids ; Triacylglycerols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The geographical variation in the composition of triacylglycerols in seeds of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.], grown in Finland, was analyzed. The total lipid content of pine seeds was slightly higher in the northernmost provenance (68 °50′N), whereas the lipid content of spruce seeds was not affected systematically by the geographical origin of the seeds. The species studied differed in the proportions of fatty acids in their triacylglycerols, though the three most abundant components were the same, i.e. oleic acid (18∶1 n9), linoleic acid (18∶2n-6) and 5,9,12-octadecatrienoic acid (18∶3 5c9c12c). These fatty acids corresponded to more than 80 mol% of the total fatty acids. According to mass spectrometric analyses, the triacylglycerols of both spruce and pine seeds consisted of the same molecular species with 52–56 acyl carbons, but in different proportions. Molecules with 54 acyl carbons represented approximately 75% of the pine and 85% of the spruce triacylglycerols, with the most abundant molecular species being 54∶5, 54∶6 and 54∶7. Some minor differences in the fatty acid composition of triacylglycerols of pine seeds from different seed collecting areas were found: the proportion of linoleic acid slightly increased whereas that of 5,11,14-eicosatrienoic acid decreased towards the northern origins. Similar differences were not found in the proportions of fatty acids in spruce seed lots. Furthermore, the proportions of triacylglycerols in both pine and spruce seeds from northern and southern collecting areas were not significantly different. The higher content of total lipids in spruce seeds compared with pine seeds may be due to the structure of the seed coat, and the lipophilic layers inside it, acting as a barrier to imbibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197778
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  • 10
    Electronic Resource
    Electronic Resource
    Micronutrient composition of xylem sap and needles as a result of P-fertilization in maritime pine (1995)
    Springer
    Trees 10 (1995), S. 52-54 
    Details
    ISSN: 1432-2285
    Keywords: Forest fertilization ; Micronutrient ; Mineral interaction ; Mineral uptake ; Xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Xylem sap and foliar compositions (P, Cu, Zn, Mn) were examined over 4 months in control and P-fertilized maritime pine in a 7-year-old plantation. The absorption of copper, zinc, and boron appears to be reduced by phosphate fertilization. Manganese concentrations are positively related to P-supply increase. Foliar analysis and sap provides the same type of information in terms of antagonism or synergism between elements but the response to treatment is more often significant with sap throughout the seasons and is completely non-existent on a single classical autumn diagnosis with foliar concentration (i.e. Zn and Cu). In consequence foliar analysis is not sensitive enough for copper or zinc deficiency diagnoses in young plantations where nutritional growth disorders appear in a short period of spring, and xylem chemistry appears to be a convenient tool in monitoring micronutrient disorders in pine plantations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197780
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  • 11
    Electronic Resource
    Electronic Resource
    Seasonal and annual variations of phosphorus, calcium, potassium and manganese contents in different cross-sections of Picea abies (L.) Karst. needles and Quercus rubra L leaves exposed to elevated CO2 (1995)
    Springer
    Trees 10 (1995), S. 55-62 
    Details
    ISSN: 1432-2285
    Keywords: Picea abies ; Quercus rubra ; Nutrients ; Carbon dioxide ; Seasonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Norway spruce and red oak trees were planted directly into the soil and enclosed in open-top chambers. For 2 years the trees were exposed to both ambient and elevated CO2 concentrations (700 μmol mol-1) and during this time variations in nutrient concentrations were studied. CO2-treated plants had decreases in global leaf concentrations of nitrogen, potassium, calcium and manganese for both species. When different areas of the foliage were analysed however, the response showed much variability between the respective sites and between species. Furthermore the nutrient concentrations changed differently as the plant material aged and this change showed inter-treatment differences. These results show how it may be important to analyse plant material of different ages and at different cell sites when studying nutrient levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192184
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  • 12
    Electronic Resource
    Electronic Resource
    Poor stomatal control of water balance and the abscission of green needles from a declining stand of spruce trees [Picea abies (L.) Karst.] from the northern Alps (1995)
    Springer
    Trees 10 (1995), S. 63-73 
    Details
    ISSN: 1432-2285
    Keywords: Forest decline ; Osmotic potential ; Picea abies ; Stomatal control ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract On a site on the west slope of the Wank in the northern Alps changes in water potential, osmotic potential and transpiration rate were measured in spruce trees during the dry summer months of 1991. The pattern of decrease in water potential and osmotic potential on days of varying evaporative demand from trees of widely different decline conditions was used to describe the relative ability of the trees to withstand drought stress. Stress diagrams served as a tool for interpreting the state of health of each tree. The criterion is independent of the water situation of the tree and the other external conditions of the respective experiment. These diagrams clearly show that the foliage of spruces with high needle losses reaches the limit of endurance relatively early. For equal evaporative demand much lower turgor levels were observed in spruces with high needle loss compared to undamaged trees. Associated with the occurrence of low turgor values was the shedding of green needles. The abscission zone was shown in sections. The accumulation of highly fluorescent substances in the bundle sheath cells of the same material was described. Incomplete to non-existent stomatal control over water loss was attributed to modifications in the cell walls of the stomata which appear to alter the ability of the guard cells to sense changes in either atmospheric or cellular hydration. Our studies point to the following situation: air pollution directly affects stomatal control, the loss of stomatal control changes the drought avoidance abilities of the foliage and, as a consequence, low turgor levels occur and premature needle abscission is induced. As site water balance decreases, either due to a dry year or to poor moisture holding abilities of the soil, these conditions become apparent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192185
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  • 13
    Electronic Resource
    Electronic Resource
    Fatty acids, starch and biomass of Scots pine needles and roots in open-air ozone exposure (1995)
    Springer
    Trees 10 (1995), S. 74-82 
    Details
    ISSN: 1432-2285
    Keywords: Ozone ; Pinus sylvestris (L.) ; Lipids ; Starch ; Biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Scots pine (Pinus sylvestris L.) seedlings were fumigated with 1.2–1.5 x ambient ozone (cumulative exposure) over 2 seasons in an open-air experiment. Starch and fatty acid concentrations were analyzed in needle and root tissue in the summer, autumn and early winter. Seedling growth was determined by measuring the height of the stem and the total shoot and root biomass. Significant decreases in growth were found in exposed seedlings, even though visible symptoms were lacking. Almost significant reductions in needle and root starch concentrations were found. In the ozone treated foliage, significant increases in myristic acid (14∶0) were detected, but the major fatty acids remained unchanged. Fatty acid ratios showed that the degree of unsaturation decreased in treated needles in the summer. In the roots of ozone treated seedlings, changes in fatty acids were different from those in the foliage. Decreases of the main root fatty acids (16∶0, 18∶0, 18∶1, 18:2, 18∶3) were detected in the summer. These results show that Scots pine is susceptible to enhanced levels of ozone. If the tropospheric ozone levels continue to increase it may have deleterious effects on Scots pine forests in Finland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192186
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  • 14
    Electronic Resource
    Electronic Resource
    Restricted lateral gas movement in Pinus strobus branches (1995)
    Springer
    Trees 10 (1995), S. 83-85 
    Details
    ISSN: 1432-2285
    Keywords: Oxygen ; Sap-flow ; Respiration ; Carbon dioxide ; Cambium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Argon gas was incorporated into the sap flowing through xylem of cut branches, or added to the air in a sealed cuvette surrounding a needle-free portion of the branch to investigate lateral movement of gases in Pinus strobus. Microdialysis was used to sample air in the xylem and evacuated vials were used to collect samples of air from cuvettes attached to branches. Argon concentrations of samples of air were measured by GC-MS. When argon was added through the sap, concentrations of argon in the xylem and in air of chambers enclosing needle stumps was greater than that of controls, but argon concentrations of air in cuvettes enclosing a needle-free portion of the branch were not greater than controls. When argon was added to cuvettes enclosing a needle-free portion of the branch, the argon did not enter the xylem and it was not emitted by needle stumps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192187
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  • 15
    Electronic Resource
    Electronic Resource
    Coniferyl alcohol oxidase — a catechol oxidase? (1995)
    Springer
    Trees 10 (1995), S. 102-107 
    Details
    ISSN: 1432-2285
    Keywords: Pinus strobus L ; Polyphenol oxidase ; Tracheid differentiation ; Wood formation ; Cell wall ; Lignin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The physico-chemical properties of coniferyl alcohol oxidase (CAO), a copper containing glycoprotein spatiotemporally associated with lignification in conifers, is reported here. By electron paramagnetic resonance spectroscopy, only type 3 copper was indicated in CAO. CAO oxidizes several laccase substrates; however, it is not a blue-copper protein and monoclonal antibodies against both native and deglycosylated CAO did not recognize any of several laccases. The N-terminal sequence of CAO, H2N-X E L A Y S P P Y X P S, was non-homologous with known enzymes. Transparent copper, tetrameric structure, aminoacid composition, phenylhydrazine and tropolone inhibition, and SDS enhancement of CAO activity indicate that CAO is an o-diphenol oxidase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192190
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  • 16
    Electronic Resource
    Electronic Resource
    Carbohydrate content of Eucalyptus gunnii leaves along an annual cycle in the field and during induced frost-hardening in controlled conditions (1995)
    Springer
    Trees 10 (1995), S. 86-93 
    Details
    ISSN: 1432-2285
    Keywords: Carbohydrates ; Eucalyptus gunnii ; Frost resistance ; Hardening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The annual changes in frost hardiness were studied for three Eucalyptus gunnii genotypes. Frost resistance evaluated on leaf discs by the electrolyte leakage method reached a maximum in the coldest period and a minimum in summer demonstrating winter frost hardening. Genotype 634 exhibited a higher intrinsic resistance than the other genotypes both in the hardened and in the non-hardened stages. Plants of this genotype were also frost acclimated in controlled conditions by a progressive decrease of culture temperature (25 to 0 °C) but the degree of hardening appeared to be lower in these conditions. The carbohydrate patterns in leaves varied with acclimation. In controlled conditions the leaves of genotype 634 exhibited a rise in sucrose, fructose and raffinose concentration up to a temperature of 10 to 7 °C which subsequently decreased. In natural conditions a comparison of the three genotypes allowed us to correlate the higher intrinsic resistance of genotype 634 to a higher soluble sugar content. During acclimation fructose and raffinose changes were also correlated to an increase in cold resistance even though the kinetics of these changes differed in controlled and natural conditions. The starch content was very low in the various genotypes in the different conditions but oligosaccharides such as stachyose and possibly verbascose were detected. The results point out the relationships occurring between increased frost resistance and changes in fructose and raffinose concentration in E. gunnii leaves.
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    URL: http://dx.doi.org/10.1007/BF00192188
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  • 17
    Electronic Resource
    Electronic Resource
    Diurnal changes in the radius of a subalpine Norway spruce stem: their relation to the sap flow and their use to estimate transpiration (1995)
    Springer
    Trees 10 (1995), S. 94-101 
    Details
    ISSN: 1432-2285
    Keywords: Stem radius variation ; Xylem sap flow ; Crown transpiration ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Diurnal changes in the stem radius of a subalpine mature Norway spruce were measured simultaneously with the flow of sap in xylem. Matric potentials in the soil were 〉 -35 kPa. The kinetics of the flow were closely related to the changes in the radius of the stem resulting from depletion of its extensible tissues. The radius of the stem oscillated daily and, fairly independently of this, fluctuated over several days. The daily shrinkage (Δd) was correlated with the daily flow through its base (Qd). When the crown transpired little and was nearly saturated during rainy days, ASd tended to increase relative to Qd. Using a linear relation, the estimates of flow by Δd deviated less than ± 10% from the values measured by heat balance, provided that the periods of calibration in their ratio of dry to rainy days were comparable to those estimated. If the two periods differed in this respect, the estimates of flow deviated up to 42%. A quadratic relation yielded estimates that depended less on weather. It reduced maximal deviations to ±22%. Since Δd additionally may represent the time pattern of the daily transpiration better than Qd, analysing changes in the radius of stems may supplement or partly replace measurements of sap flow in stems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192189
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  • 18
    Electronic Resource
    Electronic Resource
    Growth patterns of early versus late successional multipurpose trees of the western Himalaya (1995)
    Springer
    Trees 10 (1995), S. 108-113 
    Details
    ISSN: 1432-2285
    Keywords: Growth pattern ; Multipurpose ; Successional trees ; Western Himalaya
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the mid-western Himalaya (altitude 1350 m, rainfall 1100 mm), multipurpose trees found as escapees in agricultural fields or naturally growing in the forests, play an important role in providing fuel, fooder and small timber to the farmers. Shoot elogation, and tree architecture of 4 year old trees of Grewia optiva, Robinia pseudoacacia and Celtis australis (early successionals), and Quercus leucotrichophora, Q. glauca and Ilex odorata (late successionals), were analyzed. All the late successional species showed a proleptic type of bud and branch production, while the early successional trees made growth through syllepsis. The shoot elongation differed significantly (P 〈0.05) with the crown position, and ranged from 11 to 30 cm in different species. Early successional species tended to maintain a comparatively narrow crown and showed a significantly (P 〈0.05) higher ramification ratio, and multilayered canopy. The late successionals, in contrast, showed a wide crown with monolayered canopy, adapted to the weak light intensity. There was only one flush of leaves in Q. leucotrichophora and Q. glauca while in the rest of the species there were two distinct flush periods. The results are important for the management of agroforestry trees.
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    URL: http://dx.doi.org/10.1007/BF00192191
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  • 19
    Electronic Resource
    Electronic Resource
    Altered root growth and plant chemistry ofPinus sylvestris seedlings subjected to aluminum in nutrient solution (1996)
    Springer
    Trees 10 (1996), S. 135-144 
    Details
    ISSN: 1432-2285
    Keywords: Scots pine ; Aluminum ; Pollution ; Photosynthesis ; Roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract One-year-old Scots pine (Pinus sylvestris L.) seedlings were grown for 9 weeks in nutrient solutions containing 0, 0.5, 1, 2 and 4 mM aluminum nitrate (Al(NO3)3) at pH 4.2. Nine weeks exposure to Al significantly reduced total plant, shoot and root mass and caused a linear decline in proportional allocation of biomass to roots. Relative growth rate of roots declined to as low as zero. Aluminum treatment decreased calcium and magnesium uptake and increased Al content in roots and needles. After 3 weeks of exposure a 10–60% increase in total phenols in roots and a 20–40% increase in o-diphenols in roots and needles were noted. Roots affected by Al showed degeneration of meristematic cells, fewer cell divisions, deformation in cell walls and higher lignification and suberization. The majority of root apices were structurally similar to dormant roots, and a premature senescence of the entire root system was observed. Net photosynthetic rate after 6 weeks of treatment was negatively correlated with needle Al content and Al/Ca ratio (r 〈 -0.9, P 〈 0.1). The results suggest that Scots pine may be more susceptible to Al than was expected based on previous experiments.
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    Development of needle retention in Scots pine (Pinus sylvestris) in 1957–1991 in northern and southern Finland (1995)
    Springer
    Trees 10 (1995), S. 125-133 
    Details
    ISSN: 1432-2285
    Keywords: Pinus sylvestris ; Needle trace method ; Needle retention ; Long-term variation ; Reindeer browsing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The needle trace method was used to study retrospectively the long-term latitudinal variation in needle retention in Scots pine (Pinus sylvestris L.) in Finland. The mean annual summer needle retention (ANR) along the main stem varied from 3.4 to 6.0 needle sets during the period 1957–1991. The lowest values were observed in southern and the highest in northern Finland. The length of the growing season, expressed as the thermal sum (threshold value +5 °C), was negatively correlated with the mean ANR (r=-0.96). The geographical needle retention pattern (NRP) for the period 1957–1991 showed a clearly increasing trend from 1957 to 1969 (southern Finland) and to 1975 (northern Finland); thereafter, the NRP tended to decrease close to its minimum value recorded in 1991. The general level of the NRP was approximately 5.0 needle sets in northern Finland and 3.5–4.0 needle sets in southern Finland. The NRP, with its 6–12 year cycle for southern Finland, was clearly periodical. Differences in the NRP among the ten stands in southern Finland were small, whereas the said periodicity was missing and the differences were high among the stands in northern Finland. The results indicate that variation in the number of needle sets, viz. defoliation of pines, is a normal phenomenon. The role of net carbon assimilation as a regulator of the number of needle sets is discussed.
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    URL: http://dx.doi.org/10.1007/BF00192193
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    Photosynthetic acclimation to light in juveniles of two cloud forest tree species (1995)
    Springer
    Trees 10 (1995), S. 114-124 
    Details
    ISSN: 1432-2285
    Keywords: Alchornea triplinervia ; Decussocarpus rospigliosii ; Photosynthetic acclimation ; Sun/shade adaptation ; Tropical cloud forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The photosynthetic response of juveniles of Decussocarpus rospigliosii, an emergent primary forest species and shade tolerant in its juvenile stages and Alchornea triplinervia, a gap-colonizing species of tropical cloud forest in Venezuela was studied. Daily courses of microenvironmental variables and gas exchange under contrasting light conditions (gap and understory) were carried out in their natural environment and transplanted to different light regimes (shade and sun) in the field. The photosynthetic response and some anatomical characteristics of plants from different treatments were analyzed in the laboratory. Photosynthetic rates were low for both species, and were negative during some diurnal periods, related to the low photosynthetically active radiation levels obtained at both gap (6% of total radiation) and understory (2%). A. triplinervia shows higher rates (1.5–3.0 μmolm-2 -1) than D. rospigliosii (0.7–1.1 μmolm-2s-1). Both species showed increased photosynthetic rates when grown in gaps. A. triplinervia did not adjust its maximum photosynthetic rates to the prevailing light conditions. In contrast, D. rospigliosii responded to increased light levels. Both species showed low light compensation points when grown under total shade. There was a partial stomatal closure generally during midday in D. rospigliosii. A. triplinervia presented lower leaf conductances, transpiration rates and lesser stomatal control. Some leaf anatomical characteristics, in both species, were affected by variations in the light regime (i.e. increased leaf thickness, leaf specific weight and stomatal density). These results suggest that both species have the ability to respond to variations in their natural light environments, therefore maintaining a favorable carbon balance during the day.
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    URL: http://dx.doi.org/10.1007/BF00192192
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    Acceleration of leaf senescence inFagus sylvatica L. by low levels of tropospheric ozone demonstrated by leaf colour, chlorophyll fluorescence and chloroplast ultrastructure (1996)
    Springer
    Trees 10 (1996), S. 145-156 
    Details
    ISSN: 1432-2285
    Keywords: Fagus sylvatica ; Open-top chamber ; Ozone ; Plastoglobuli ; Senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract From April 1988 to October 1991 3-year-old seed propagated beech (Fagus sylvatica L.) trees were exposed in open-top chambers to four different levels of air pollution: (1) charcoal filtered air, (2) ambient air, (3) ambient air plus 30 nl 1-1 ozone during the summer, and (4) ambient air plus 30 nl 1-1 ozone during the summer and 20 nl 1-1 SO2 and NO2 during the winter. Leaf colour was studied in the autumns of 1989 and 1991 and a close relationship between ozone dose and premature senescence was found. A correlation also exists between the colour groups and chlorophyll fluorescence (Fv/Fm). Ozone fumigation increases the size and speeds up the development of the plastoglobules. This is described using an index based on the volume of plastoglobules as a percentage of chloroplast volume. The index was significantly higher for ozone fumigated plants than for control plants during August to November 1989. According to all three methods it is concluded that low levels of ozone accelerate leaf senescence processes inF. sylvatica. There are indications that leaves of the first and the second flush react differently to the ozone treatment. Irrespective of the ozone treatment a special cell wall structure, probably a local suberization, is confined to the subsidiary cells in leaves of the first flush.
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    Influence of UV-B radiation on photosynthetic activity and chlorophyll fluorescence kinetics in Norway spruce [Picea abies (L.) Karst.] seedlings (1996)
    Springer
    Trees 10 (1996), S. 172-176 
    Details
    ISSN: 1432-2285
    Keywords: Ultraviolet-B radiation ; Norway spruce ; Picea abies (L.) Karst. ; Photochemical activity ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Norway spruce [Picea abies (L.) Karst.] seedlings were grown in greenhouses with two supplemental levels of ultraviolet-B (UV-B) radiation. Photochemical efficiency of photosystem II and vitality index were determined monthly. At the end of the experiment, growth, chlorophyll content and photosynthetic rates were measured. The data indicate that low temperature in winter affected light dependent processes in experimental plants including control, while the rise of ambient temperatures, moderate this effect. The synergistic effects of UV-B radiation and low temperatures could only be observed in the second winter period. Measurements of net photosynthetic activity in the second winter period showed significant differences between treated and untreated plants.
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    URL: http://dx.doi.org/10.1007/BF02340768
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    Changes in dormancy levels ofFraxinus excelsior L. embryos at different stages of morphological and physiological maturity (1996)
    Springer
    Trees 10 (1996), S. 177-182 
    Details
    ISSN: 1432-2285
    Keywords: Embryo dormancy ; Fraxinus excelsior ; In vitro germination ; Seed development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dormancy status ofFraxinus excelsior embryos at different developmental stages under environmental conditions was examined over a period of 2 years. For each sampling date the length of the fruit, of the seed, and of the embryo were measured, and the embryological stage determined. The depth of dormancy was assayed by the germination behaviour of isolated embryos under aseptic conditions on an agar medium without nutrients. As an approach towards a quantitative estimate of the dormancy status, the degree of inhibiton of germinative growth in the embryonic organs was evaluated on the basis of four categories from none to full germinative growth. From these ratings a dormancy index was calculated, expressing the mean dormancy status of the embryos at a given date. Embryo dormancy already became apparent during embryogenesis and reached its highest level during the later phase of reserve deposition in the seed. A marked loss of embryo dormancy occurred during the phase of maturation drying in autumn, followed by a moderate increase in winter. In hydrated seeds in spring the embryo was gradually released from dormancy and enlarged further. In maintaining the embryo ofF. excelsior in a developmental but not germinative mode, dormancy mechanisms within the embryo and the endosperm, combined with environmental factors, may be involved.
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    Effects of long-term open-air exposure to fluoride, nitrogen compounds and SO2 on visible symptoms, pollutant accumulation and ultrastructure of Scots pine and Norway spruce seedlings (1996)
    Springer
    Trees 10 (1996), S. 157-171 
    Details
    ISSN: 1432-2285
    Keywords: Conifer ; Fluoride ; Nitrogen ; Sulphur dioxide ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of SO2, aqueous fluoride (NaF) and a solution of nitrogen compounds (NH4NO3) on the visible symptoms, pollutant accumulation and ultrastructure of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.] seedlings were studied in an open-air experiment lasting for 3 consecutive years. Visible injury symptoms were most pronounced in combination exposures and whenever F was applied. Visible symptoms correlated well with needle pollutant concentrations. Exposure to NaF increased needle F contents particularly when F was applied with SO2 or NH4NO3. This suggests that a reduction in N or SO2 emissions, in F polluted areas, could improve the condition of conifers via decreased accumulation of phytotoxic F in the needles. Norway spruce needles accumulated 2–10 times as much S and F as those of Scots pine. Microscopic observations showed various changes in the needle mesophyll cell ultrastructure. In both species, exposure to SO2 increased significantly the amount of cytoplasmic vacuoles, suggesting detoxification of excess sulphate or low pH. F treatments resulted in a significant enlargement of plastoglobuli in Scots pine and a darkening of plastoglobuli in Norway spruce. All exposures enhanced the accumulation of lipid bodies. An increased portion of translucent plastoglobuli was most pronounced in N treatments. Many of the ultrastructural changes and visible symptoms appeared only as number of years exposed increased, indicating that long-term experiments are needed. Both visible symptoms and ultrastructural changes pointed to the more pronounced sensitivity of Norway spruce compared to Scots pine. Ultrastructural results mostly supported earlier qualitative observations of F, N and SO2 effects on needle mesophyll cell ultrastructure. However, no reduction of thylakoids in SO2 containing exposure or curling of thylakoids in F exposure could be detected in the present study.
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    URL: http://dx.doi.org/10.1007/BF02340767
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    Anaerobic induced ethanol synthesis in the stems of greenhouse-grown conifer seedlings (1996)
    Springer
    Trees 10 (1996), S. 183-188 
    Details
    ISSN: 1432-2285
    Keywords: Anaerobic respiration ; Fermentation ; Hypoxia ; Pseudotsuga menziesii ; Pinus ponderosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ethanol synthesis was induced in stem segments from greenhouse-grown conifer seedlings by placing them in a N2 atmosphere at 30 °C for 24 h. Stems from ponderosa pine,Pinus ponderosa Dougl. ex Laws., sugar pine,Pinus lambertiana Dougl., Pacific silver fir,Abies amabalis Dougl. ex Forbes, and lodgepole pine,Pinus contorta Dougl. ex Loud, produced the highest quantities of ethanol. This group also had the smallest and slowest growing stems. Within each of these species the amount of ethanol produced was inversely related to the stem volume. Stems from western hemlock,Tsuga heterophylla (Raf.) Sarg., grand fir, Abies grandis Dougl. ex Forbes, Douglas-fir,Pseudotsuga menziesii (Mirb.) Franco, and western redcedar,Thuja plicata Donn ex D. Don, all produced equivalent but low ethanol concentrations. These species had the largest and fastest growing stems. In this group only grand fir exhibited an inverse relationship between ethanol concentrations and stem volume. The relative amounts of ethanol synthesized by stems from Douglas-fir, western hemlock and western redcedar seedlings were not the same as subsequently observed in logs from mature trees of the same species under field conditions. Differences in the anaerobic environments for the two stem types could have affected the quantities of ethanol produced. The observed high amounts of ethanol produced by the stems from pine species were discussed in terms of their ability to handle periods of anaerobic stress or hypoxia.
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    URL: http://dx.doi.org/10.1007/BF02340770
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    Effects of N addition rates on the productivity ofPicea sitchensis,Thuja plicata, andTsuga heterophylla seedlings (1996)
    Springer
    Trees 10 (1996), S. 189-197 
    Details
    ISSN: 1432-2285
    Keywords: Nitrogen ; Picea sitchensis ; Relative growth rates ; Thuja plicata ; Tsuga heterophylla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seedlings ofPicea sitchensis, Thuja plicata andTsuga heterophylla were supplied N hydroponically at one of four exponentially increasing rates of addition (0.09, 0.07, 0.05, or 0.025 gN-1 day-1) for up to 3 months in a naturally illuminated glasshouse. Relative growth rates (RGR) were analyzed as a function of N uptake, the allocation of assimilated N to foliage (LNFR), foliar N concentrations (Nla) and met assimilation rates (NAR), which were combined to estimate N productivity (RGR per unit whole-plant N concentration). Nitrogen accumulation, biomass and N partitioning and RGR and its components varied with species in response to the different N regimes.T. heterophylla had the lowest maximum wholeplant N concentrations (wpN) and specific absorption rates for N and exhibited the least plasticity in root: shoot ratios as wpN increased from 11–21 mg g-1. In all species, RGR increased linearly with wpN, while LNFR increased curvilinearly. Foliar N (Nla) increased linearly with wpN and NAR increased linearly with Nla. The RGRs ofT. heterophylla were highest at wpNs up to 18 mg g-1, a result of higher foliar N use efficiencies (NAR/Nla). However, RGR increased more with wpN inT. plicata andP. sitchensis. Although LNFR increased with wpN in all species, foliar N use efficiency declined, possibly due to an increased partitioning of foliar soluble N to non-photosynthetic compounds. Thus, in each species, N productivity did not increase above intermediate levels of wpN: 14 mg g-1 inT. heterophylla, 16 mg g-1 inP. sitchensis and 17 mg g-1 inT. plicata.
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    Assessing the impact of ozone on photosynthesis of European beech (Fergus sylvatica L.) in environmental chambers (1996)
    Springer
    Trees 10 (1996), S. 268-275 
    Details
    ISSN: 1432-2285
    Keywords: Beech ; Ozone ; Photosynthesis ; Closed chambers ; Critical Levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An exposure — response study with proportionalto-ambient ozone levels was conducted in closed chambers on 3-year-old European beech (Fagus sylvatica L.) of montane origin. The fumigation started in April 1990 and lasted for a single growing season. Climate data and ozone concentrations monitored at an experimental station of the Institute for Applied Plant Biology, Schönenbuch, Switzerland were simulated in the exposure chambers 12 days later (1*O3). To test exposure-response relations three additional treatments were applied, subambient (0.2*O3) and two proportionally increased ozone treatments (1.5*O3 and 2*O3). The photosynthetic behaviour of the trees in August revealed the light reactions to be less affected than parameters which are related to the dark reactions of photosynthesis. Assimilation (A350), apparent carboxylation efficiency (CE), and maximum photosynthetic capacity (A2500) were reduced with increasing ozone concentration. For the ozone response of CE and A2500 ‘Critical Levels’ were calculated.
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    Effects of N addition rates on the productivity ofPicea Sitchensis,Thuja plicata, andTsuga heterophylla seedlings (1996)
    Springer
    Trees 10 (1996), S. 198-205 
    Details
    ISSN: 1432-2285
    Keywords: Nitrogen ; Photosynthesis ; Picea sitchensis ; Thuja plicata ; Tsuga heterophylla
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of differing, exponentially increasing rates of N addition (0.025, 0.05, 0.07 and 0.09 gN gN-1day-1) on photosynthesis, discrimination against13C and partitioning of foliar N to chlorophyll and major photosynthetic proteins were compared in seedlings of the evergreen conifersPicea sitchensis, Thuja plicata andTsuga heterophylla. T. heterophylla had the lowest range of foliar N concentrations (Nlm). Across species, photosynthetic rates (A) increased linearly with Nlm to a maximum at 21 mg g-1 and declined at higher Nlms. Species differences inA resulted from differences in Nlm, not from differences in photosynthetic N use efficiency. Self-shading may have causedA to decline at a high Nlm inP. sitchensis andT. plicata. Measurements of gas exchange and δ13C suggested that carboxylation capacity increased more than did stomatal conductance as Nlm increased. The responses were small and confined to Nlms associated with the lesser rates of N addition. Concentrations of total protein, ribulose 1,5-bisphosphate carboxylase (RUBISCO) and the light harvesting chlorophyll a/b protein complex (LHC) increased with Nlm, but the fraction of foliar N allocated to RUBISCO and LHC increased with Nlm only inP. sitchensis and only between the 0.025 and 0.05N regimes. The responsiveness ofA and concentrations of RUBISCO to Nlm were less than reported for deciduous C3 species.
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    Slightly elevated ozone exposure causes cell structural changes in needles and roots of Scots pine (1996)
    Springer
    Trees 10 (1996), S. 207-217 
    Details
    ISSN: 1432-2285
    Keywords: Ozone ; Pine ; Fine structure ; Needles ; Roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Scots pine (Pinus sylvestris L.) seedlings were fumigated with 1.2–1.5 x ambient ozone over 2 seasons in an open-air experiment. Fumigation started in the early spring and continued into late autumn during both years. Needle and root cell structures were analyzed in the summer, autumn and early winter following the second fumigation period. Under the light microscope an increase in the intercellular space and disintegrating cells in the mesophyll tissue near the stomata and stomatal cavities were observed in the ozone-exposed needles. Darkening of chloroplast stroma, increased plastoglobulus size and decreased chloroplast size were characteristic ultrastructural changes associated with ozone exposure. In addition, less dense grouping of the chloroplasts in the needles of elevated ozone-exposed seedlings as compared to the controls (background ozone) was observed in the early winter. Fewer starch grains and an increased accumulation of tannin-like substances were detected in both mycorrhizal and uninfected roots of ozone-exposed seedlings as compared to the control seedlings. For the first time, we were able to show that the ozone-induced darkening of needle chloroplast stroma is a reversible symptom. An increased frequency of frost injury symptoms indicated that the winter hardening process was disturbed in the needles of ozone-treated seedlings.
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    Estimation of canopy density and irradiance in 20- to 40-year-old birch stands (Betula pubescens Ehrh. andBetula pendula Roth) (1996)
    Springer
    Trees 10 (1996), S. 223-230 
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    ISSN: 1432-2285
    Keywords: Betula pubescens Ehrh ; Betula pendula Roth ; Birch ; LAI ; Crown free projection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three different experiments in birch (Betula pubescens Ehrh. andBetula pendula Roth) stands were conducted during summer 1991: an evaluation of the accuracy of the vertical tube method measuring crown free projection (CFP) in four birch stands; a study of relative irradiance (RI; photosynthetically active radiation, PAR), in birch stands differing in stem density and basal area; and an estimation of the CFP in different types of birch stands and the correlation between RI and CFP. The results indicate that the number of observation points well distributed over an area of 0.1 ha can vary between 50 and 200 to achieve sufficient accuracy. There were no significant differences in the CFP estimates made on the same plot by different observers including an untrained observer. CFP was related to basal area, stem number and diameter sum in a non-linear regression, CFP = A*e-BX. The correlations between RI and basal area, density and diameter sum, respectively, were 0.54, 0.57 and 0.67 for PAR. The coefficients of determination for RI (PAR) and CFP were high (0.86).
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    Carbon and water balance in Polylepis sericea, a tropical treeline species (1996)
    Springer
    Trees 10 (1996), S. 218-222 
    Details
    ISSN: 1432-2285
    Keywords: Carbon balance ; Polylepis sericea ; Treeline ; Tropical Andes ; Water balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Polylepis sericea trees grow well above the continuous forest line in the Venezuelan Andes. In these environments, extreme daily temperature ranges can occur at any time of the year and trees experience a 4 month dry period. The purpose of this work was to study carbon and water relations of this species in the field during wet and dry seasons in order to understand this species' success at such high altitudes. Leaf gas exchange (portable system in open mode) and leaf water potential (pressure chamber) were measured at 1–2 h intervals during several daily courses at 4000 m elevation in the Páramo de Piedras Blancas. CO2 assimilation versus leaf temperature curves were also obtained for this species in the laboratory. Clear differences in the measured parameters were observed between seasons. For a wet season day, maximum CO2 assimilation rate was 7.4 μmol m-2 s-1 and leaf conductance was relatively constant (approximately 100 mmol m-2 s-1)In the dry season day, maximum CO2 assimilation rate was 5.8 μmolm-2 s-1 and leaf conductance was close to 60 mmolm-2 s-1. Minimum leaf water potentials measured were -1.3 MPa for the wet and -2.2 MPa for the dry season. The CO2 assimilation-leaf temperature relationship showed a 13.4°C leaf temperature optimum for photosynthesis with maximum and minimum compensation points of 29.5 and -2.8°C, respectively. Maximum night-time respiration was relatively high (2.7 (imol) m-2 s-1)Our results show thatP. sericea maintains a highly positive carbon balance through all daily courses, even though there is a slight water stress effect during the dry season; this suggests that its carbon assimilation machinery is well adapted to the low temperatures and seasonal water stress found in the high tropical mountains.
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    Effects of age and site quality on the distribution of biomass in Scots pine (Pinus sylvestris L.) (1996)
    Springer
    Trees 10 (1996), S. 231-238 
    Details
    ISSN: 1432-2285
    Keywords: Scots pine ; Biomass ; Allocation ; Age ; Single tree
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The distribution of the above-ground and below-ground biomass of Scots pine in southern Finland were investigated in trees of different ages (18–212 years) from two types of growth site. Secondly, some structural regularities were tested for their independence of age and growth site. Trees were sampled from dominant trees which could be expected to have a comparable position in stands of all ages. All stands were on sorted sediments. The biomass of the sample trees (18 trees) was divided into needles, branch sapwood and heartwood, stem sapwood and heartwood, stem bark, stump, large roots (diameter 〉20 cm), coarse roots (five classes) and fine roots. The amount of sapwood and heartwood was also estimated from the below-ground compartments. Trees on both types of growth site followed the same pattern of development of the relative shares of biomass compartments, although the growth rates were faster on the more fertile site. The relative amount of sapwood peaked after canopy closure, coinciding with the start of considerable heartwood accumulation. The relative amount of needles and fine roots decreased with age. The same was true of branches but to a lesser degree. The relative share of the below-ground section was independent of tree age. Foliage biomass and sapwood cross-sectional area were linearly correlated, but there were differences between the growth sites. Needle biomass was linearly correlated with crown surface area. The fine root to foliage biomass ratio showed an increasing trend with tree age.
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    Effects of bending stress on taper and growth of stems of youngEucalyptus regnans trees (1996)
    Springer
    Trees 10 (1996), S. 239-246 
    Details
    ISSN: 1432-2285
    Keywords: Bending stress ; Stem shape ; Radial growth rate ; Eucalyptus regnans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A glasshouse experiment investigated the effect of bending stress on stem radial and height growth and stem taper ofEucalyptus regnans seedlings. Eighteen-week-old, potted seedlings were bent continuously for 8 weeks with a static bending stress. The bending treatment was then removed and the seedlings grown for another 12 weeks. Other seedlings were stayed vertically throughout the experiment whilst control seedlings were neither bent nor stayed. Seedlings were rotated every 2 days to prevent reaction wood developing asymmetrically in the stems of bent trees. Bent trees had higher radial growth rates, developed more tapered stems and had higher safety factors (the ratio of stem radius to the minimum radius required to prevent the tree toppling over) than unbent seedlings. They produced a band of tension wood in their stems and ceased height growth whilst bent. When bending ceased, they resumed normal radial and height growth. Unbent trees developed more cylindrical stems. There were no differences in growth behaviour between stayed and control trees. Bent and unbent trees all developed a butt swell, the taper of which was not affected by treatment. It was concluded that bending stress has substantial effects on both the size and taper of tree stems. However, the development of butt swell is independent of the bending stress applied. The results were considered in relation to biomechanical theories of tree stem development.
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    Nutrient dynamics in crown tissues of cork-oak (Quercus suber L.) (1996)
    Springer
    Trees 10 (1996), S. 247-254 
    Details
    ISSN: 1432-2285
    Keywords: Evergreen oaks ; Macronutrients ; “Montado” ; Seasonal patterns ; Tissue nutrient contents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The seasonal fluctuation of N, P, K, Ca and Mg in leaves, young stems and fruits of young and matureQuercus suber trees growing at the same site was studied. Nutrient dynamics within the tree appeared to be linked to phenological events. Leaves maximized their nutrient contents throughout summer whereas stems maintained rather constant values during most of the year. Before the spring growth flush they apparently acted as temporary reservoirs for some nutrients, translocated from leaves or other organs, so that such nutrients would be easily invested in the new tissues. A significant investment was made in sink organs like flowers and fruits. The tree probably relies not only on leaves but also on other nutrient reservoirs like older branches and roots for an adequate supply to those sinks and to the spring growth. The importance of the sampling dates and the basis of expression used for nutrient concentrations has also been emphasized. Nutrient contents and seasonal trends of the studied trees were similar to those of other evergreen oaks, although somewhat higher values for N, K, and Mg were found. Moreover, soil nutrient contents in the studied “montado” were much lower than in other Iberic oak stands. However the nutrient status and requirements of cork-oak suggest high (or at least adequate) nutrient availability to the trees. The mechanisms by which this could be achieved are discussed.
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    Microautoradiographic detection of CO2 fixation in lenticel chlorenchyma of youngFraxinus excelsior L. stems in early spring (1996)
    Springer
    Trees 10 (1996), S. 255-260 
    Details
    ISSN: 1432-2285
    Keywords: CO2 fixation ; Fraxinus excelsior L. ; Lenticels ; Microautoradiography ; Stem chlorenchyma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microautoradiography indicated that 1-year-oldFraxinus excelsior L. stem chlorenchyma assimilated external14CO2 in mid-April, when buds were swollen, but before bud-break. The lenticel regions showed the highest amount of radioactively labeled assimilates. Labeled assimilates declined in the tangential direction with increasing distance from lenticels, suggesting that14CO2 entered the stem through the open intercellular spaces of lenticels. In the radial direction, the amount of radioactively labeled assimilates did not constantly decline with growing distance from the lenticel entrance. It was high in all lenticel phelloderm cells, which had high chlorophyll autofluorescence and very small starch grains, highest in the adjacent 4–6 rows of chlorenchyma, which had larger starch grains that increased in size towards the interior rows, and much lower in the inner cortex chlorenchyma, which had large starch grains. We suggest that the main function of the lenticel chlorenchyma (lenticel phelloderm plus 4–6 rows of adjacent cortex chlorenchyma) is the refixation of respiratory CO2 which could easily leave the stem intercellular spaces, rather than the fixation of external CO2. The lenticel chlorenchyma could reduce the loss of respiratory CO2 by its photosynthetic activity.
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    Uptake of ammonium and nitrate ions from acid mist applied to Sitka spruce [Picea sitchensis (Bong.) Carr.] grafts over the course of one growing season (1996)
    Springer
    Trees 10 (1996), S. 261-267 
    Details
    ISSN: 1432-2285
    Keywords: Wet N inputs ; Labelled N ; N partitioning ; N accumulation ; Per cent incorporation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cloned Sitka spruce grafts were subjected to NH4NO3 mist (1 mm day-1 equivalent) acidified with H2SO4, for 4 days a week, from April until November. Three N treatments at pH 5.0 used 0.01 mol m-3 15NH4 15NH3, 1.6 mol m-3 15NH4 NO3 or 1.6 mol m-3 NH4 15NO3. At pH 2.5, the treatments were15NH4 15NO3,15NH4NO3 and NH4 15NO3 all at 1.6 mol m-3. At the end of the growing season,15N was found in every part of the trees, even when NH4NO3 was supplied at 0.01 mol m-3. It was shown that both $$NH_{4^ + } $$ and $$NO_{3^ - } $$ could enter needles to a similar degree and be transported to the roots. No differences between pH treatments or clones could be demonstrated. Entry of labelled N via the roots, in those trees with unprotected compost, was reflected in higher fine root15N content, but no change in shoot15N levels. Per cent incorporation expressed as labelled N as a percentage of total N, was generally at its highest in bark, and in older needles in all treatments, values ranging from 5 to 11%. When15N content was expressed as total content for each tree part on a per tree basis, 25–36% was found in current year needles, with a further 12% in current year bark. The most reproducible data was that for dry weight of tree parts as per cent of the whole tree, where proportions compared closely between treatments and the two clones used. The implications of the results for cuticular transport mechanisms, N storage and internal cycling are discussed.
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    The effect of crown position and date of sampling on biomass, nutrient concentrations and contents of needles and shoots in European larch (1996)
    Springer
    Trees 10 (1996), S. 339-350 
    Details
    ISSN: 1432-2285
    Keywords: European larch ; Nutrient ; Biomass ; Needle ; Shoot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The nutrient concentrations and contents of needles and shoots of 22-year-old European larch (Larix decidua Mill.) were evaluated with respect to crown position, age of tissues and sampling date during a complete growing season. Concentrations of N, P, K, Ca, Mg and Zn in the needles and of N, P and K in the shoots differed significantly among the dates of sampling. The concentrations of N and Mn in the needles and all nutrients in the shoots (except Mg) also differed significantly with crown position. Maximum needle biomass was observed in the middle crown position (55% of the total) and maximum shoot biomass, in the lower crown position (52% of the total). Maximum needle and shoot nutrient contents were observed in the middle position of the living crown for long shoot, short shoot-1, short shoot-2, short shoot-3 and, short shoot-4 age classes while highest contents for short shoot-5 and short shoot-6 age classes were observed in the lower crown position. Biases up to 42% for Mg in the needles and 200% for K in the shoots were obtained when only long shoot tissues are used for content evaluation. For needles and shoots, Mg and K are more difficult nutrients to evaluate. A sampling methodology is proposed for evaluating nutrient contents of the living crown.
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    A model of the gas exchange response ofPicea abies to habitat conditions (1996)
    Springer
    Trees 10 (1996), S. 277-287 
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    ISSN: 1432-2285
    Keywords: Picea abies ; Norway spruce ; Leaf gas exchange ; Net photosynthesis ; Stomatal conductance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Databases describing branch gas exchange ofPicea abies L. at two montane forest sites, Lägeren, Switzerland (National Forschungsprojekt 14 of the Schweizerische Nationalfonds) and Oberwarmensteinach, Germany (Bayerische Forschungsgruppe Forsttoxikologie), were analyzed in conjunction with a physiologically based model. Parameter estimates for describing carboxylase kinetics, electron transport, and stomatal function were derived, utilizing information from both single factor dependencies and diurnal time course measurements of gas exchange. Data subsets were used for testing the model at the branch level. Most of the observed variation in gas exchange characteristics can be explained with the model, while a number of systematic errors remain unexplained. Factors seen as contributing to the unexplained residual variation and not included in the model are light acclimation, degree of damage in adjustment to pollutant deposition, needle age, and cold stress effects. Nevertheless, a set of parameter values has been obtained for general application with spruce, e.g., for use in calculating canopy flux rates and to aid in planning of focused leaf and canopy level experiments. The value of the model for estimating fluxes between the forest and the atmosphere must be evaluated together with measurements at the stand level.
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    URL: http://dx.doi.org/10.1007/BF02340773
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    Photoinhibition in cork-oak leaves under stress: influence of the bark-stripping on the chlorophyll fluorescence emission inQuercus suber L. (1996)
    Springer
    Trees 10 (1996), S. 288-292 
    Details
    ISSN: 1432-2285
    Keywords: Bark-stripping ; Fluorescence emission ; Quercus suber L. ; Water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Quercus suber is the primary source for industrial cork and becomes bark-stripped every 9–10 years. Recurring cork extraction is a major stress factor and the large water loss from the stripped trunk surface may affect the water balance and tree productivity. To evaluate the effect of bark-stripping, fluorescence emission and stomatal conductance of leaves were determined in groups of bark-stripped and control trees. Fv/Fm ratio was found to be significantly lower in bark-stripped trees indicating a reduced photosynthetic efficiency of PSII. Photosynthesis was not found to be stomata limited. The reduction in Fv/Fm resulted from a decline in maximum and variable fluorescence while the initial fluorescence of the dark-adapted state (Fo) remained constant. A general decline in photosynthetic efficiency of PSII was found in all trees during the summer, probably reflecting the prolonged environmental stresses during a hot and dry season. Additional stress caused by the bark-stripping seems to enhance the susceptibility to photoinhibition of the trees.
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    Magnesium deficiency treatment causes reductions in photosynthesis of well-nourished Norway spruce (1996)
    Springer
    Trees 10 (1996), S. 293-300 
    Details
    ISSN: 1432-2285
    Keywords: Norway spruce ; Magnesium deficiency ; Photosynthesis ; Carboxylation efficiency ; Starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to investigate effects of magnesium deficiency on Norway spruce [Picea abies (L.) Karst.] photosynthesis, 100 well-nourished 5-year-old spruce trees were grown in sand culture, individually supplied with circulating nutrient solutions. Mineral nutrients were added to the nutrient solutions in optimal quantities and optimal relations to nitrogen. Magnesium was supplied at 0.203, 0.041 and 0.005 mM in order to simulate optimal nutrition, moderate deficiency and severe deficiency. Parameters of photosynthetic gas exchange, chlorophyll, magnesium and starch concentrations were determined in current-year and 1-year-old needles during one growing season. By mid May — 6 months after onset of the Mg deficiency treatments in late autumn — CO2-assimilation rates of 1-year-old needles were significantly decreased independent of the severity of the deficiency treatment, whereas the chlorophyll concentrations did not differ from the controls. The occurrence of yellowing symptoms during July did not further influence the Mg deficiency effect on photosynthesis. In contrast to 1-year-old needles, significant reductions of photosynthesis and chlorophyll in current-year needles were only caused by severely deficient Mg supply. Mg deficiency affected carboxylation efficiency but not light use efficiency. From the accumulation of starch in the needles, up to 30-fold of the controls, the conclusion has been drawn that reactions of CO2-fixation were affected by reduced carbohydrate export. The light-dependent pigment reduction, leading to the typical tipyellowing of needles, clearly reflects a secondary effect of Mg deficiency.
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    Transpiration and drought resistance of Douglas-fir seedlings exposed to excess ammonium (1996)
    Springer
    Trees 10 (1996), S. 301-307 
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    ISSN: 1432-2285
    Keywords: K ; P ; Pseudotsuga menziesii ; Root/shoot ratio ; Soil acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a pot trial growth and transpiration of 3-year-old Douglas-fir seedlings on an acid, sandy soil was examined at a deficient (30 kg N ha-1 year-1) and an excessive level (120 kg N ha-1 year-1 of NH4 application. Dissolved ammonium sulphate was applied to the pots weekly for two growing seasons. In half of the pots a complete set of other nutrients was applied in optimal proportions to the applied nitrogen. Water supply was optimal and transpiration was recorded. At the end of the second treatment season irrigation was stopped for 2 weeks during dry and sunny weather. Both high application of NH4 and additional nutrients increased shoot growth and transpiration demand in the first treatment year. The root system was smaller at higher N level and this reduced water uptake accordingly. In the second year the combination of high NH4 + and additional nutrients affected root functioning predominantly due to salinity effects and this seriously decreased water uptake capacity and shoot water potentials, finally resulting in tree death. Without addition of other nutrients the high NH4 + application resulted in a high degree of soil acidification, which damaged the roots, that showed a decrease in water uptake capacity. At the low NH4 supply level soil acidification was lower, and root functioning was not affected, and the trees recovered quickly from the imposed drought. Higher needle K and P status depressed transpiration rates at the low NH4 application rate.
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    Differential growth and recovery rates following defoliation in related deciduous and evergreen trees (1996)
    Springer
    Trees 10 (1996), S. 308-316 
    Details
    ISSN: 1432-2285
    Keywords: Herbivory ; Plant-insect interactions ; Leaf lifespan ; Pinus ; Larix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Deciduous larches,Larix spp., and evergreen pines,Pinus spp., are sympatric Pinaceae conifers. Adjacent monocultures of 10-year-oldLarix decidua Mill, andPinus resinosa Ait. were subjected to single-season artificial defoliation by clipping from 0% to 99% of each needle. Survival, above-ground productivity, and architecture were measured for 36 months.P. resinosa andL. decidua exhibited differential relationships with defoliation intensity and recovery time. Two months after treatment, defoliation reduced larch height growth but had no effect on radial growth. By contrast,P. resinosa stem radial growth was reduced immediately, but height growth was not decreased until the following year. Pine leader growth and above-ground biomass following 66% defoliation never recovered to control values or 33% defoliated pines. Conversely, defoliated larch quickly recovered from an initial growth loss to eliminate all treatment effects on biomass. The plasticity in architectural response found in larch, but not pine, might partially account for defoliation tolerance. BothP. resinosa andL. decidua exhibited non-linear responses to defoliation. These patterns may be caused partially by the uneven distribution of nutrients within needles, rather than a simple function of leaf area lost to defoliators. Concentrations of 13 nutrients inP. resinosa were highest either in the mid-(Ca, Mg, S, Zn, B, Mn, Fe, Al and Na) or basal-(N, P, K, and Cu) section. The relatively low nutrient content in needle tips may contribute to similar biomass productivity between trees defoliated 33% and controls. Removal of needle mid-sections significantly reduced whole-plant productivity. In contrast,L. decidua nutrients are concentrated in the distal sections. Nutrient concentrations were generally highest in larch. Our results agree with an emergent prediction of the carbon/ nutrient balance theory that defoliation more severely reduces growth of evergreen than deciduous species. These results are discussed within the physiological, ecological and evolutionary context of allocation theory, with implications for natural resource management and plant-insect interaction theory.
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    Effects of pre-severance light quality on the vegetative propagation ofEucalyptus grandis W. Hill ex Maiden (1996)
    Springer
    Trees 10 (1996), S. 317-324 
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    ISSN: 1432-2285
    Keywords: Carbohydrates ; Eucalyptus grandis ; Photosynthesis ; Propagation ; Red to far-red ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two-leaf, two-node cuttings were taken fromEucalyptus grandis stockplants grown under different light qualities (red to far-red ratios of 0.4, 0.7, 1.3, 3.5 and 6.5) at a constant photon flux density (200 μmol m-2 s-1). Two experiments tested effects of pre-severance light quality on cutting morphology, post-severance gas exchange, carbohydrate status and rooting of cuttings. The best rooting percentage was achieved by cuttings with longer stems and greater stem volume from stockplants grown at lower red to far-red (R∶FR) ratios. Generally, rooting success was associated with low pre-severance starch and water-soluble sugar concentrations, and a greater total water-soluble carbohydrate (TWSC) content per cutting. Rooting was associated with well maintained stem starch and an increase in stem TWSC during the propagation period. Gas exchange of cuttings was measured between 28 and 33 days after severance. Rooting percentages at 35 days after severance were positively and linearly related to net photosynthetic rate and stomatal conductance. In unrooted cuttings there was a net release of CO2 which increased significantly with an increase in pre-severance R∶FR ratio. These results demonstrate that stockplant environment may significantly modify the morphology and physiology of subsequent cuttings, and that cutting morphology, and stored and current photosynthates have a significant influence on rooting.
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    Pyridine nucleotide levels and activities of dehydrogenases in cambial derivatives ofRobinia pseudoacacia L. (1996)
    Springer
    Trees 10 (1996), S. 325-330 
    Details
    ISSN: 1432-2285
    Keywords: Cambial differentiation ; Glucose-6-phosphate dehydrogenase ; 6-Phosphogluconate dehydrogenase ; NAD kinase ; Pyridine nucleotides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Despite the importance of the vascular cambial differentiation, little is known about its regulation. In order to address this problem we attempted to biochemically characterize differentiating xylem and phloem elements during the early stages of development. By applying techniques of quantitative histochemistry we show that the total pool size of pyridine nucleotides is similar in the phloem (PD) and xylem (XD) oriented derivatives of the cambial zone of trees ofRobinia pseudoacacia L. Within the PD zone, the amount of NAD + NADH exceeded that of NADP + NADPH [around 600 versus 200 pmol (mg dry weight)-1], possibly indicative of a preponderance of catabolic pathways (ratio of NADH∶NAD about 1). In contrast, the NADP(H) system dominated in the XD zone. This coincided with a high activity of NAD kinase. In addition, the extractable activities of the key enzymes of the oxidative pentose phosphate pathway, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, were greatly increased. At a ratio of NADPH∶NADP of approximately 1, this could be indicative of increased rates of reductive biosyntheses, and could thus well be involved in early steps of the formation of phenols and lignin monomers. Taken together, this first approach clearly shows that phloem-oriented and xylem-oriented cambial descendents exhibit distinct differences in their biochemical patterns even in early stages of differentiation.
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    Phytohormones in needles of healthy and declining silver fir (Abies alba Mill.): I. Indole-3-acetic acid (1996)
    Springer
    Trees 10 (1996), S. 331-338 
    Details
    ISSN: 1432-2285
    Keywords: Indole-3-acetic acid ; Abies ; Needle senescence ; Forest decline ; SO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Levels of indole-3-acetic acid (IAA) were determined in needles from silver fir (Abies alba Mill.) trees in the northern Black Forest. IAA was quantified by gas chromatography (GC) as 1-heptafluorobutyryl-IAA-methylester (HFB-IAA-ME) using electron capture detection. Prior to GC analysis, extensive purification of needle extracts was performed employing two HPLC steps. Peak identity of HFB-IAA-ME was confirmed by combined gas chromatography-mass spectrometry in selected samples. Levels of IAA in needles belonging to different needle age-classes exhibited a cyclic seasonal pattern with highest concentrations in winter and lowest levels in spring when bud-break occurred. Such a cyclic seasonal pattern of IAA levels was also observed in needles from declining fir trees or fir trees suffering from a strong sulfur impact (S-impact) in the field due to a local SO2 source. Levels of IAA increased with increasing needle age. This age dependency of IAA concentrations was most pronounced in late autumn when IAA levels were high and nearly disappeared in spring when IAA levels reached their minimum. In needles from declining fir trees or fir trees suffering from a strong S-impact in the field, IAA levels hardly increased with increasing needle age. It is suggested that in healthy trees high levels of IAA protect older needles from abscission and that the considerable losses of older needles of declining fir trees or of fir trees under S-impact are a consequence of the low levels of IAA found in older needles of such trees.
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    Relationships between carbon and hydrogen isotope ratios and nitrogen levels in leaves ofClusia species and two other Clusiaceae genera at various sites and different altitudes in Venezuela (1996)
    Springer
    Trees 10 (1996), S. 351-358 
    Details
    ISSN: 1432-2285
    Keywords: Altitude ; Carbon isotope ratio ; Clusiaceae ; Crassulacean acid metabolism ; Deuterium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Samples of the Clusiaceae generaClusia, Oedematopus andDystovomita were collected at various sites and different altitudes in northern and south-western Venezuela. Analyses of stable isotopes of carbon and hydrogen and of leaf-nitrogen levels were performed on the dried samples. Correlations among these variables, i.e. carbon isotope discrimination (Δ), hydrogen isotope ratio (δD) and N-levels, and with altitude were assessed. In the samples, where values of Δ above 15‰ indicate predominant performance of C3 photosynthesis, there were slight tendencies of increasing Δ, δD and N-levels with increasing altitude and of increasing Δ with increasing N. Although these correlations taken separately were not statistically significant, they support each other and indicate increasing transpiration and increased leaf-nutrient supply at increasing altitude. Performance of crassulacean acid metabolism (CAM) in species ofClusia appears to be restricted to altitudes below 1500 m a.s.l. There was a significant negative correlation of Δ with altitude in the samples, where values of Δ below 10‰ indicated predominant performance of CAM. This suggests that phases II and IV of CAM are progressively suppressed towards the upper altitudinal limit of CAM inClusia in northern Venezuela. It is concluded that among the large number of environmental factors and combinations thereof, which determine the expression of CAM inClusia and trigger C3-CAM transitions in C3/CAM intermediate species, low availability of water is the most important.
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    The effect of light levels on daily patterns of chlorophyll fluorescence and organic acid accumulation in the tropical CAM treeClusia hilariana (1996)
    Springer
    Trees 10 (1996), S. 359-365 
    Details
    ISSN: 1432-2285
    Keywords: Chlorophylla fluorescence quenching ; Citric acid ; Malic acid ; Photochemistry ; Photosynthetic electron transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sandy plains are characteristic of the coastal region of Brazil. We investigated the diel patterns of changes in organic acid levels, leaf conductance and chlorophylla fluorescence for sun-exposed and shaded plants ofClusia hilariana, one of the dominant woody species in the sandy coastal plains of northern Rio de Janeiro state. Both exposed and shaded plants showed a typical CAM pattern with considerable diel oscillations in organic acid levels. The degradation of both malic and citric acids during the midday stomatal closure period could lead to potential CO2 fixation rates of 28 μmol m-2 s-1 in exposed leaves. Moreover, exposed leaves exhibited large increases in total non-photochemical quenching (qN) accompanied by a substantial decrease in effective quantum yield during the course of the day. However, these potential high rates of CO2 fixation and the increases inqn of exposed plants were not enough to maintain the primary electron acceptor of photosystem II (qA) in a low reduction state, similar to that of shaded plants. As a result, there was a moderate increase in the reduction state of qA throughout the day. Most of the decline in photochemical efficiency of exposed leaves ofC. hilariana was reversible, as evidenced by the high levels of pre-dawn potential quantum yields (Fv/Fm) and their rapid recovery after sunset. However, the depletion of the organic acid pool in the afternoon resulted in an accentuated subsequent drop in Fv/Fm, suggesting that prolonged periods of water stress accompanied by high irradiance levels may expose plants ofC. hilariana in unprotected habitats to the danger of photoinhibition.
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    Lipids and lipolytic enzymes in the trunkwood ofRobinia pseudoacacia L. during heartwood formation (1996)
    Springer
    Trees 10 (1996), S. 366-375 
    Details
    ISSN: 1432-2285
    Keywords: Acyllipids ; Heartwood formation ; Phospholipids ; Robinia pseudoacacia L. ; Sterols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The radial distribution of membrane and storage lipids was determined in the trunkwood ofRobinia pseudoacacia L. The trees were felled in November at the time of heartwood formation and fluctuations in the amount and composition of phospholipids, free sterols, steryl esters, diand triacylglycerols, and free fatty acids were investigated across the sapwood-heartwood boundary. The individual compounds were identified and quantified by thin layer chromatography, enzymatic and colorimetric assays, and by capillary gas chromatography. Phospholipids show a significant decrease towards the boundary area, and in the heartwood only trace amounts can be detected. The same pattern is observed for free sterols in the sapwood; in the heartwood, however, they reach maximum values with increasing depth of the trunk. Steryl esters exhibit a complementary behaviour by accumulating at the periphery of the heartwood. No concentration changes are found in the total amounts of diacylglycerols and free fatty acids. In contrast, the triacylglycerol concentration declines steadily across the trunk. With regard to qualitative composition, free fatty acids and the fatty acid moieties of the esterified constituents vary in their chain length from 14 to 24 carbon atoms and have up to three double bonds. A radial gradient in the ratio saturated/unsaturated fatty acids can be observed: except for the phospholipid fraction the relative amounts of unsaturated fatty acids increase in centripetal direction. Seven phospholipids were identified: phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, diphosphatidylglycerol, and phosphatidic acid, which constitutes the major proportion. In the sterol group, sitosterol is the most abundant component. The composition of the esterified sterols remains constant across the trunk cross-section, whereas the relative frequencies of individual free sterols change markedly.
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    URL: http://dx.doi.org/10.1007/BF02185640
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    Lipids and lipolytic enzymes in the trunkwood ofRobinia pseudoacacia L. during heartwood formation (1996)
    Springer
    Trees 10 (1996), S. 376-381 
    Details
    ISSN: 1432-2285
    Keywords: Acylesterhydrolase ; Heartwood formation ; Lipase ; Robinia pseudoacacia L. ; Phospholipases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The radial profile of lipase and phospholipase activities was determined in the trunkwood ofRobinia pseudoacacia L. The trees were felled in November at the time of heartwood formation and alterations in the enzymatic activities were investigated across the sapwood and heartwood. Methods employed include gaschromatographic, colorimetric and enzymatic assays. On a dry weight basis, the hydrolysis of the artificial substrate pnitrophenylpalmitate shows a maximum activity in growth ring 4; however, the assay has proved not to be specific for lipase. In contrast, lipase analyses (triacylglycerol acylhydrolase; E.C. 3.1.1.3) with an authentic substrate show activity peaks in growth rings 1 and 4. With protein as a reference the highest activity is found in growth ring 5. A similar tendency is observed for phospholipase A1 (E.C. 3.1.1.32) and phospholipase A2 (E.C. 3.1.1.4). Phospholipase C (E.C. 3.1.4.3) activity decreases towards the sapwood-heartwood boundary; negligible traces of activity are detected in the heartwood, whereas, based on the protein content, growth ring 4 yields maximal activity. Phospholipase D (3.1.4.4) exhibits the same radial pattern with regard to protein content as a reference. On a dry weight basis there is a significant increase within the sapwood area, while in the heartwood the activity drastically decreases. The enzyme activities are discussed in relation to degradative processes within the plasma membranes and the hydrolysis of reserve lipids during heartwood formation.
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    Interactive effects of elevated CO2 and O3 on photosynthesis and biomass production of clonal 5-year-old Norway spruce [Picea abies (L.) Karst.] under different nitrogen nutrition and irrigation treatments (1996)
    Springer
    Trees 10 (1996), S. 382-392 
    Details
    ISSN: 1432-2285
    Keywords: CO2 ; Ozone ; Norway spruce ; Gas exchange ; Biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To study the single and combined effects of elevated carbon dioxide (CO2), ozone (O3), nitrogen nutrition, and water supply on photosynthetic gas exchange and biomass accumulation of Norway spruce, a four-factorial experiment was conducted in closed environmental chambers. Each factor was applied at two levels: (i) ambient and elevated (ambient + 200 μl 1-1) CO2, (ii) 20 and 80 nl 1-1 O3, (iii) low and high nitrogen fertilization, and (iv) a well watered and a drought treatment. Neither elevated O3 nor CO2 significantly changed stomatal conductances of spruce needles. Adverse effects of elevated O3 on photosynthetic parameters such as net assimilation rate and carboxylation efficiency occurred only when the plants were well watered and in a good nutritional status. After 6 weeks enhanced atmospheric CO2 resulted in increased net assimilation rates provided that nutrition was well balanced and plants were well watered. Acclimation processes became apparent and are interpreted as a consequence of sink regulation. While O3-effects were apparent only in biomass of 1-year-old plant material, elevated CO2 resulted in higher biomass of the buds expanding during the exposure and increased root biomass significantly. Above and below-ground biomass were strongly influenced by the water and nutrition treatments.
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    The effect of long term CO2 enrichment on the growth, biomass partitioning and mineral nutrition of Sitka spruce (Picea sitchensis (Bong.) Carr.) (1996)
    Springer
    Trees 10 (1996), S. 393-402 
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    ISSN: 1432-2285
    Keywords: Elevated CO2 ; Sitka spruce ; Growth ; Allocation ; Nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sitka spruce [Picea sitchensis (Bong.) Carr.] seedlings were grown for 3 years in an outside control plot or in ambient (∼355 μmol mol-1) or elevated (ambient + 350 μmol mol-1) atmospheric CO2 environments, within open top chambers (OTCs) at the Institute of Terrestrial Ecology, Edinburgh. Sequential harvests were carried out at the end of each growing season and throughout the 1991 growing season, five in all. Plants grown in elevated CO2 had, (i) 35 and 10% larger root/shoot ratios at the end of the first and third season, respectively, (ii) significantly higher summer leader extension relative growth rates, which declined more rapidly in early autumn than ambient grown plants, (iii) after three growing seasons a significantly increased mean annual relative growth rate, (iv) consistently lower foliar nutrient concentrations, and (v) after two growing seasons smaller total projected needle areas. Plants grown inside OTCs were taller, heavier and had a smaller root/shoot ratio than those grown outside the chambers. There was no effect of CO2 concentration on Sitka spruce leaf characteristics, although leaf area ratio, specific leaf area and leaf weight ratio all fell throughout the course of the 3 year experiment.
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    Changes in root growth patterns of (Picea abies) spruce roots by inoculation with an ectomycorrhizal fungusPisolithus tinctorius and jasmonic acid treatment (1996)
    Springer
    Trees 10 (1996), S. 410-414 
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    ISSN: 1432-2285
    Keywords: Ectomycorrhiza ; Jasmonic acid ; Picea abies ; Pisolithus tinctorius ; Spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Symbiosis between fungi and plant roots forming a mycorrhiza involves extensive interactions at the molecular level between both partners. The role of plant hormones in the regulation of mycorrhizal infection is not known to involve jasmonates. Their endogenous levels increase during pathogen attack; however, little has been done on their involvement in mycorrhizae. In our recent work, root growth patterns of 2-month-old spruce seedlings after inoculation withPisolithus tinctorius and/or jasmonic acid (JA) treatment were studied using a paper-sandwich technique. Changes in root length, the degree of branching, presence and length of root hairs, and infection parameters were followed using a stereomicroscope. The first mycorrhizal contact of hyphae with roots was significantly accelerated upon treatment with 0.5 μM JA. Interactions between root hairs and fungal hyphae were seen by scanning electron microscopy. The multiplication of root hairs of non-mycorrhized seedlings treated with 5.0 μM JA and changes of the root surface were observed by the same technique.
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    URL: http://dx.doi.org/10.1007/BF02185645
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    Early season cuticular conductance and gas exchange in two oaks near the western edge of their range (1996)
    Springer
    Trees 10 (1996), S. 403-409 
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    ISSN: 1432-2285
    Keywords: Cuticular conductance ; Gallery forests ; Leaf development ; Photosynthesis ; Quercus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seasonal changes in minimum leaf conductance to water vapor (gmin), an estimate of cuticular conductance, and photosynthetic gas exchange in two co-occurring oak species in north-east Kansas (USA) were examined to determine if leaf gas exchange characteristics correlated with differences in tree distribution. Bur oak (Quercus macrocarpa Michx.) is more abundant in mesic gallery forest sites, whereas chinquapin oak (Quercus muehlenbergii Englm.) is more abundant in xeric sites. Early, during leaf expansion, gmin was significantly lower in chinquapin oak than in bur oak, though midday water potentials were similar. After leaves had fully expanded, gmin decreased to seasonal minimum values of 4.57 (±0.274) mmol m-2 s-1 in bur oak, and 2.66 (±0.156) mmol m-2 s-1 in chinquapin oak. Water potentials at these times were significantly higher in chinquapin oak. As leaves were expanding, photosynthesis (Anet) was significantly higher in chinquapin oak than in bur oak. Later in the growing season, Anet and gleaf increased dramatically in both species, and were significantly higher in bur oak relative to chinquapin oak. We concluded that bur and chinquapin oak have a number of leaf gas exchange characteristics that minimize seasonal water loss. These characteristics are distinct from trees from more mesic sites, and are consistent with the distribution patterns of these trees in tall-grass prairie gallery forests.
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    Carbon partitioning in Norway spruce: amounts of fructose 2,6-bisphosphate and of intermediates of starch/sucrose synthesis in relation to needle age and degree of needle loss (1990)
    Springer
    Trees 4 (1990), S. 9-15 
    Details
    ISSN: 1432-2285
    Keywords: Carbon partitioning ; Fructose 2,6-bisphosphate ; Needle development ; Needle loss ; Picea abies ; Starch/sucrose/intermediates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Intermediates involved in carbon partitioning between starch and sucrose [dihydroxyacetone phosphate + glyceraldehyde 3-phosphate (TP), 3-phosphoglyceric acid, fructose 6-phosphate (F6P), fructose 2,6-bisphosphate (F26BP), in addition to glucose, fructose, sucrose and starch] were analysed in lyophilized needles of Norway spruce (Picea abies L. Karst). Samples were taken from all distinct parts of first and second order branches and the analysed data related to season, needle age, needle position and degree of needle loss (control and class 2 approx. 30%–40% needle loss). Positive and inverse correlations of F26BP, an important regulator of carbon partitioning between starch and sucrose, and F6P or TP existed in all samples. F26BP levels were highest in developing needles and gradually decreased during maturation, which is possibly indicative of changes in the relative sink strength during development (switch from import to export of sucrose). In class 2 needles the amount of F26BP was significantly increased. Together with nearly unaltered levels of sucrose but only slightly decreased amounts of starch the results can be taken as evidence for impaired carbon export in our class 2 samples. The data are discussed with respect to needle development and a possible impact of both air pollutants and mineral deficiency at the location from which the samples were taken.
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    The ion concentration of dew condensed on Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) needles (1990)
    Springer
    Trees 4 (1990), S. 22-26 
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    ISSN: 1432-2285
    Keywords: Deposition ; Dew ; Pine ; Pinus sylvestris ; Spruce ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Dew droplets collected with pipettes from coniferous needles were analysed for their ionic composition. Almost all samples of dew taken from Scots pine trees (Pinus sylvestris) showed significantly higher ion concentrations than those taken from Norway spruce trees (Picea abies). This can be explained by the micromorphology of the needle surface. The higher microscale roughness of the wax layer of a pine needle causes a more efficient flux of atmospheric aerosol particles compared to the spruce needle surface. Dew on coniferous needles is shown to be capable of maintaining pH values below 3 for several hours.
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    Vascular differentiation in branch junctions of trees: circular patterns and functional significance (1990)
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    Trees 4 (1990), S. 49-54 
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    ISSN: 1432-2285
    Keywords: Branch junctions ; Circular vessels ; Pinus ; Quercus ; Vascular differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Regions of spiral vascular tissues and circular vessels occur normally in branch junctions. Their size and frequency increase continuously with age and stem width. This phenomenon is general and was found in all the 15 species studied. The differentiation of narrow spiral vessels with non-functional circular vessels decreases water conductivity through branch junctions leading to hydraulic segmentation of lateral branches from the main stem. Possible hormonal mechanisms controlling circular vascular patterns and narrow vascular elements are discussed.
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    URL: http://dx.doi.org/10.1007/BF00226240
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    Seasonal variation in the monoterpenes in needles of Picea abies (L.) Karst. (1990)
    Springer
    Trees 4 (1990), S. 34-40 
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    ISSN: 1432-2285
    Keywords: Seasonal fluctuation ; Needle ; Picea abies ; (Mono) terpene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This investigation was conducted to obtain information about the fluctuations in composition and amount of needle monoterpenes during the development of spruce needles. Studies conducted with two Norway spruce clones clearly revealed the existence of fluctuations. In juvenile needles, the amounts of the oxygenated terpenes increase constantly with age during the first 2 months of needle growth. The hydrocarbon terpenes dominate within the first weeks, some of them even showing a very distinct first maximum within the first 3 weeks after bud burst. All terpenes, including the oxygenated ones, have a maximum in June/July, which favours the hypothesis of a substitution of the hydrocarbons later on. There are significant changes even in mature needles of Norway spruce. The terpene level of 1-year-old needles of the clonal trees increased from spring to early summer and then dropped again towards winter. In addition, fluctuations in mature needles were shown for a set of ten wild trees. Needles of the same age class, which emerged in 1986, were sampled 4 times from 1986 to 1988. The needle terpene concentrations of the 1 -year-old needles were considerably lower in spring at the time of bud burst than in autumn. The terpene level of older needles thus seems to be influenced by biosynthetic and catabolic activities.
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    An analysis of needle yellowing in healthy and chlorotic Norway spruce(Picea abies) in a forest decline area of the Fichtelgebirge(N.E. Bavaria) (1990)
    Springer
    Trees 4 (1990), S. 55-67 
    Details
    ISSN: 1432-2285
    Keywords: Forest decline ; Needle yellowing ; Chlorophylls ; Carotenoids ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In a forest decline area (Fichtelgebirge, N.E. Bavaria, FRG), annual time courses of chloroplast pigments in both healthy and chlorotic Norway spruce were studied. The seasonal time courses of green and apparently healthy trees did not generally differ from those reported in the literature for spruce trees of other regions. Chlorophyll content increased from May to October, remained relatively constant or declined slightly during the fall and early winter, and finally decreased markedly from March to early May when pigment is at its minimum before bud break. The annual maximal chlorophyll content increased with needle age from the current year's needles to 4-yearold needles. While carotene content reached its highest concentration in August, the xanthophylls did not peak until February or March. Pigment dynamics of chlorotic trees with lower concentrations, corresponded to those of undamaged trees. Chlorophyll deficits resulted from less pigment formation as well as pigment loss during the growing period. Even when the content of total chlorophyll was low, the ratio of chlorophyll a/chlorophyll b remained almost unchanged. In conjunction with the chlorophyll reductions, a decrease in the chlorophyll/carotenoid ratio and an increase in the xanthophyll/carotene ratio occurred. The periods of needle-chlorophyll reduction did not correlate with those periods of highest concentrations of atmospheric sulphur dioxide, the main air pollutant at the stand. However, chlorophyll formation ceased in the older needle age classes of chlorotic trees when the new flush was sprouting, indicating that nutritional deficiencies affect needle yellowing more than possible direct needle damage by air pollutants.
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    Contents of ATP and ADP in needles of Norway spruce in relation to their development, age, and to symptoms of forest decline (1990)
    Springer
    Trees 4 (1990), S. 68-74 
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    ISSN: 1432-2285
    Keywords: ATP ; ADP ; Forest decline ; Needle development ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Pool sizes of ATP and ADP were analysed in freeze-stopped, lyophilised homogenates of needles from Norway spruce [Picea abies (L.) Karst.]. Control experiments in which possible changes in adenylate pools during sample acquisition were investigated did not reveal significant differences between needles taken from branches in situ or within a 30-min period after cutting off a branch. In addition, pool sizes of ADP and ATP were not affected by changes in light intensity (between 60 and 1500 μE*-m-2*s-1), which inevitably occur when samples have to be taken from the upper region of older trees. Levels of ATP and ADP showed considerable seasonal changes (May through October) with the highest ratios of ATP/ADP in developing needles. In general, there was a tendency towards increased ratios of ATP/ADP with increasing needle age. This observation was corroborated by analyses of needles from spruce trees of different age and growing under different conditions. Needles from declining trees or from trees specifically fumigated with low concentrations of ozone and sulphur dioxide had significantly increased ratios of ATP/ADP compared to controls. The results are discussed with respect to physiological responses connected with natural senescence and induced ageing.
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    Effects of ozone on starch accumulation in Norway spruce (Picea abies) (1990)
    Springer
    Trees 4 (1990), S. 107-110 
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    ISSN: 1432-2285
    Keywords: Needles ; Ozone ; Picea abies ; Starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Fumigation with 100 μg/m3 and 200 μg/m3 ozone in closed-top fumigation chambers induced starch accumulation in chloroplasts of Norway spruce. This accumulation was probably due to a partial inhibition of the starch translocation at night. The intensity of the effect was dependent on the season and the age of the needles. The accumulation was reversed in winter. It is therefore unlikely that such an effect has much significance for plant health.
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    Rhythmic growth fluctuations in forest trees of Central Europe and the Front Range in Colorado (1990)
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    Trees 4 (1990), S. 99-106 
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    ISSN: 1432-2285
    Keywords: Dendrochronology ; Abrupt growth changes ; Periodicities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Growth ring sequences in conifers and broadleaved trees show abrupt growth reductions persisting for several years. The frequency and duration of such reductions in almost 10000 trees in forest stands of Central Europe, in particular Switzerland, and in the Front Range, Colorado, USA, is related to species, climate and weather, and geographical unit. The growth reductions in the populations investigated are concentrated in certain periods and, in all species examined, essentially related to periods of drought in the spring and summer months. During the years covered by the study (1850–1985), periods of growth reduction occur in Central Europe, the Front Range, Colorado, and also in the Hudson Valley, New York, at irregular intervals of 6–34 years, and on average every 13–14 years. The growth reduction periods normally do not show synchronism between the three areas investigated. Regionally valid growth periodicities can only be definitely determined through the examination of a very large amount of material comprising a number of species growing in different forest stands and on different sites within a major phytosociological unit. Findings from studies on trees in different climatic areas or on few samples scarcely allow reliable comparisons.
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    Influence of phloem transport on flower abscission in Hibiscus rosa-sinensis (1990)
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    Trees 4 (1990), S. 128-135 
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    ISSN: 1432-2285
    Keywords: Fruit abscission ; Hibiscus rosa-sinensis ; Microautoradiography ; Phloem transport ; Starch deposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Flowering cultivars of Hibiscus rosa-sinensis L. were either cross-pollinated or self-pollinated. Fruit set was observed on 52% of the cross-fertilized flowers, while only 4.6% of the self-fertilized flowers were not abscised. Once during fruit and seed growth, the subtending leaf was exposed to 14CO2, and translocation of labelled photoassimilate was recorded by macro- and microautoradiography. Phloem transport into the raphe occurred in both fruits with fertilized and fruits with non-fertilized ovules. Since empty ovules showed some sink strength, it is assumed that growth of vegetative seed-tissue signalizes the retardation of completion of the abscission process. During fruit growth a considerable amount of starch is deposited in the distal layer of the abscission zone. Part of this starch is consumed during growth of cross-fertilized fruits.
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    Tubule bundle-inclusions in vacuoles of Tamarix aphylla L. mesophyll cells (1990)
    Springer
    Trees 4 (1990), S. 136-141 
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    ISSN: 1432-2285
    Keywords: Mesophyll ; Tamarix aphylla ; Tubule bundles ; Vacuoles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Vacuoles of differentiating mesophyll cells of Tamarix aphylla contain an amorphous electron-dense material in which stacks of parallel aligned striations are embedded. Cross-sections of the striations disclosed that they represent profiles of longitudinally sectioned bundles of tubules (tubule outer diameter 9.0 nm, tubule wall thickness 1.8 nm). In advanced mesophyll cell development, the amorphous vacuolar material disappears, whereas the bundles of tubules turn into bundles of double helices (double helix diameter 14.5 nm). Cytochemical treatment of mesophyll cells with the enzymes pepsin and trypsin has revealed that both the bundles of tubules/double helices and the embedding material are constituted of protein. The possible functional role of the vacuolar inclusions is discussed.
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    Endogenous levels of oxygen, carbon dioxide and ethylene in stems of Norway spruce trees during one growing season (1990)
    Springer
    Trees 4 (1990), S. 150-154 
    Details
    ISSN: 1432-2285
    Keywords: Carbon dioxide ; Conifers ; Ethylene ; Gaschromatography ; Mass spectrometry ; Oxygen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The trees sampled in this study came from two stands of Norway spruce, Picea abies (L.) Karst., near Stockholm, Sweden, differing in mean age and height. Holes were bored perpendicular to the stem surface, and gas samples were taken from the outer part of the sapwood throughout one growing season. Endogenous levels of molecular oxygen (O2), carbon dioxide (CO2) and ethylene in the outer sapwood were determined by combined gas chromatography — mass spectrometry (GC-MS) and GC. O2 concentrations began to decrease as growth started in spring. The lowest levels (〈5%) were recorded around mid-summer. In the younger stand concentrations remained below 5% until September. In October, O2 concentrations in the sapwood were similar to those of air. Concentrations of CO2 were below 1% in spring, but began to rise in May, peaking a month later at approximately 10%. Thereafter a slow decrease occurred until October, by which time levels had returned to those recorded in spring. Ethylene concentrations in the older stand reached 75 ppm early in May, while levels in the younger stand peaked at around 30 ppm later in May. Thereafter ethylene levels in both stands started to decrease down to ppb levels. The correlation between determined gas levels and physiological events associated with the seasonal growth cycle in temperate zones is discussed.
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    Nauclea diderrichii: rooting of stem cuttings, clonal variation in shoot dominance, and branch plagiotropism (1990)
    Springer
    Trees 4 (1990), S. 164-169 
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    ISSN: 1432-2285
    Keywords: Apical dominance ; Clonal variation ; Nauclea diderrichii ; Plagiotropism ; Vegetative propagation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nauclea diderrichii (De Wild, and Th. Dur.) Merill (Rubiaceae), an indigenous hardwood of West Africa, is increasingly being grown commercially. This study investigates the potential for vegetative propagation and clonal selection, and raises some fundamental questions about the physiology of apical dominance and of plagiotropism. Rooting ability was high, with up to 100% rooting in 2–4 weeks, when different Indole-3-butyric acid (IBA) concentrations and leaf areas were tested. Auxin applications greatly increased the numbers of roots per cutting. The decapitation of unbranched plants revealed clonal variation in apical dominance and also in the establishment of outright dominance by the two shoots formed from the outgrowth of the axillary buds of the opposite leaves at the top node. Regression analysis of the Dominance Ratio (length of dominant: length of the sub-dominant shoot at the time of achieving dominance) against overall lateral bud activity (r = 0.82), showed that when the two top shoots co-dominate they provide a more powerful source of Correlative Inhibition than when one of the top shoots dominates the other. The imposition of plagiotropism in the axillary bud occurred over a period of a few days as the terminal and axillary buds emerged from the stipule. Growth of accessory buds on intact plants and debranched cuttings was orthotropic. These results are discussed with regard to the role of the leaf in root formation and the understanding of dominance relationships, branching and crown development in trees.
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    Phloem transport in Picea abies (L.) Karst. in mid-winter (1990)
    Springer
    Trees 4 (1990), S. 179-186 
    Details
    ISSN: 1432-2285
    Keywords: 14C translocation ; Microautoradiography ; Phloem loading/unloading ; Picea abies ; Symplastic transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Translocation of 14C assimilates was studied on four different transport systems of Picea abies branches after induced activation in January. 14CO2 assimilation of terminal shoots for 48 h at 25° C resulted in phloem loading and basipetal transport of 14C photosynthate into the following, older shoot generations. 14C import was enhanced, when these older shoot generations were kept in the dark. Microautoradiographs of the labelled terminal shoots showed that 14C assimilates were exported from needles via sieve elements of the leaf traces and loaded into the latest increment of the axial secondary phloem. No 14C label appeared in the obliterated sieve cells or in the tracheids. In addition, 14C photosynthate accumulated densely in the chlorophyllous cells of the cortex and in cells of the resin ducts, indicating certain sink activity. In the darkened 2-year-old shoot, imported 14C photosynthate was concentrated in the functional secondary phloem, while some 14C label was unloaded into the latest xylem increment. When 6-year-old shoots were exposed to 14CO2 for 48 h in the light, 14C assimilates accumulated in the phloem of the leaf trace and in the latest increment of the axial secondary phloem. However, a substantial amount of radioactivity was unloaded into ray cells and phloem parenchyma cells. Thus, the presence of functioning phloem in needles and twigs of P. abies during winter allows long-distance translocation and radial distribution of assimilates according to existing source-sink relations.
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    Hybrid poplar stomata unresponsive to changes in environmental conditions (1990)
    Springer
    Trees 4 (1990), S. 191-197 
    Details
    ISSN: 1432-2285
    Keywords: Unresponsive stomata ; Stomatal conductance ; Hybrid poplar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The factors affecting stomatal conductance (gs) of I-214 (Populus euramericana) and a hybrid poplar, Peace (P. koreana x P. trichocarpa), were examined in the field and under controlled environment conditions. Unusual opening of the stomata was observed with Peace leaves at all positions. Ontogenetic changes in gs were similar between these two poplar species in the light. However, the dark/light ratio of gs in Peace poplar varied from 0.58 to 1.23 with the insertion level while that of I-214 poplar was zero except for the third leaf from the top. The gs of I-214 poplar changed with time of the day, varying from 0.74 mol m-2s-1 in the morning to zero at night, while the gs of Peace poplar changed only from the minimum value of 0.23 mol m-2s-1 at night to the maximum of 0.48 mol m-2s-1 in the morning. Under severe water stress, below -1.5 MPa, which decreased the gs of I-214 poplar to almost zero, the gs of Peace poplar remained about onethird of that observed with well-watered leaves. Exposure to a relatively high concentration of O3 caused the gs of I-214 poplar to decrease nearly to zero but had no effect on the gs of Peace. Stomata of Peace poplar were not affected by ABA and the gs did not change even with 10-4 M ABA, while the gs of I-214 decreased to almost zero on the application of this concentration of ABA.
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    URL: http://dx.doi.org/10.1007/BF00225315
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    Wind breakage of trees initiated by root delamination (1990)
    Springer
    Trees 4 (1990), S. 225-227 
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    ISSN: 1432-2285
    Keywords: Buttress roots ; Failure mechanism ; Root delamination ; Wind breakage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary There are different types of tree failure under wind loading. Here a special mechanism is discussed by which redirectioning of the tensile forces acting in the tree stem causes a lateral force to become effective away from the stem-root transition contour line. This force leads to delamination of the root followed by development of an axial crack running up the stem, until total stem failure by fibre buckling on the compression side of the stem completes the destruction. It is shown that buttress roots could reduce the danger associated with this failure mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225319
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    Confocal laser scanning microscopy of fluorescently stained wood cells: a new method for three-dimensional imaging of xylem elements (1991)
    Springer
    Trees 5 (1991), S. 1-4 
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    ISSN: 1432-2285
    Keywords: Confocal laser scanning microscopy ; Wood cell structure ; Three-dimensional imaging ; Lignification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Xylem cells were fluorescently stained with periodic acid — Schiff reaction or with Schiffs reagent alone and studied by confocal laser scanning microscopy. Single images with extremely low depth of focus, series of optical sections, computed stereo scopic images and “shadow casting” images as well as x-z images are obtained. In contrast to scanning electron microscopy, not only are the surfaces imaged, but elements concealed by other structures can be visualized by this system. Quantitative data on cell depth are provided and differences in lignification are detected.
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    URL: http://dx.doi.org/10.1007/BF00225328
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    Impairment of gas exchange and structure in birch leaves (Betula pendula) caused by low ozone concentrations (1991)
    Springer
    Trees 5 (1991), S. 5-13 
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    ISSN: 1432-2285
    Keywords: Ozone ; Betula pendula ; Leaf gas exchange ; Leaf structure ; Senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Injury caused by low O3 concentrations (0, 0.05, 0.075, 0.1 μl 1-1) was analyzed in the epidermis and mesophyll of fully developed birch leaves by gas exchange experiments and low-temperature SEM: (I) after leaf formation in O3-free and ozonated air, and (II) after transferring control plants into ozonated air. In control leaves, autumnal senescence also was studied in O3-free air (III). As O3 concentration increased, leaves of (I) stayed reduced in size, but showed increased specific weight and stomatal density. The declining photosynthetic capacity, quantum yield and carboxylation efficiency lowered the light saturation of CO2 uptake and the water-use efficiency (WUE). Carbon gain was less limited by the reduced stomatal conductance than by the declining ability of CO2 fixation in the mesophyll. The changes in gas exchange were related to the O3 dose and were mediated by narrowed stomatal pores (overriding the increase in stomatal density) and by progressive collapse of mesophyll cells. The air space in the mesophyll increased, preceded by exudate formation on cell walls. Ozonated leaves, which had developed in O3-free air (II), displayed a similar but more rapid decline than the leaves from (I). In senescent leaves (III), CO2 uptake showed a similar decrease as in leaves with O3 injury but no changes in mesophyll structure and WUE. The nitrogen concentration declined only in senescent leaves in parallel with the rate of CO2 uptake. A thorough understanding of O3 injury and natural senescence requires combined structural and functional analyses of leaves.
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    URL: http://dx.doi.org/10.1007/BF00225329
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    Ammonium and nitrate uptake rates and rhizosphere pH in non-mycorrhizal roots of Norway spruce [Picea abies (L.) Karst.] (1991)
    Springer
    Trees 5 (1991), S. 14-21 
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    ISSN: 1432-2285
    Keywords: Ammonium ; Calcium ; Nitrate ; Picea abies ; Rhizosphere pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Relationships between root zone temperature, concentrations and uptake rates of NH 4 + and NO 3 − were studied in non-mycorrhizal roots of 4-year-old Norway spruce under controlled environmental conditions. Additionally, in a forest stand NH 4 + and NO 3 − uptake rates along the root axis and changes in the rhizosphere pH were measured. In the concentration (Cmin) range of 100–150 μM uptake rates of NH 4 + were 3–4 times higher than those of NO 3 − The preference for NH 4 + uptake was also reflected in the minimum concentration (Cmin) values. Supplying NH4NO3, the rate of NO 3 − uptake was very low until the NH 4 + concentrations had fallen below about 100 μM. The shift from NH 4 + to NO 3 − uptake was correlated with a corresponding shift from net H+ production to net H+ consumption in the external solution. The uptake rates of NH 4 + were correlated with equimolar net production of H+. With NO 3 − nutrition net consumption of H+ was approximately twice as high as uptake rates of NO 3 − In the forest stand the NO 3 − concentration in the soil solution was more than 10 times higher than the NH 4 + concentration (〈100 μM), and the rhizosphere pH of non-mycorrhizal roots considerably higher than the bulk soil pH. The rhizosphere pH increase was particularly evident in apical root zones where the rates of water and NO 3 − uptake and nitrate reductase activity were also higher. The results are summarized in a model of water and nutrient transport to, and uptake by, non-mycorrhizal roots of Norway spruce in a forest stand. Model calculations indicate that delivery to the roots by mass flow may meet most of the plant demand of nitrogen and calcium, and that non-mycorrhizal root tips have the potential to take up most of the delivered nitrate and calcium.
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    URL: http://dx.doi.org/10.1007/BF00225330
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    Analysis of stand density effects on canopy structure: a conceptual approach (1991)
    Springer
    Trees 5 (1991), S. 44-49 
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    ISSN: 1432-2285
    Keywords: Crown dimensions ; Canopy structure ; Stand density ; Stand structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A few assumptions were used to generate a series of specific, quantitative predictions for the relationships between stand density and various dimensional measures of canopy structure. The predictions, each indicating an increase in mean crown size as density decreased, appeared to be reasonable and intuitive. Predictions were compared to data for two conifer species with different crown forms, Pinus contorta var. latifolia and Abies lasiocarpa. Results of these comparisons were mixed — the linear, directly measured dimensions were consistent with predicted relationships, but dimensions calculated from the linear measures were not. Re-examination of the original assumptions indicated that the model should account for crown shyness (engagement/disengagement) to adequately reflect the influence of stand density on canopy structure. The results also indicated a strong association between stand height and measures of mean crown size. Mean crown size of lodgepole pine was altered much more by density than was mean crown size of subalpine fir, due primarily to the different relative shade tolerances of the two species. Some of the observed differences between species may also reflect the range of densities examined and uneven spacing in the unmanaged natural stands.
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    URL: http://dx.doi.org/10.1007/BF00225334
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    Regulation of photoassimilate allocation in Pinus sylvestris seedlings by the nutritional status of the mycorrhizal fungus Suillus variegatus (1991)
    Springer
    Trees 5 (1991), S. 36-43 
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    ISSN: 1432-2285
    Keywords: Microautoradiography ; Mycorrhiza ; Pinus sylvestris ; Suillus variegatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seedlings of Pinus sylvestris L. were grown on defined nutrient solutions on carbon filters, either sterile or infected with the basidiomycete Suillus variegatus O. Kuntze. After mycorrhizas were established, the shoot of the seedling was subjected to 14CO2 photosynthesis. 14C-labelled photoassimilates were translocated to both mycorrhizas and non-infected root tips. Microautoradiographs of mycorrhizas indicated that omission of external sugars did not affect the formation of mycorrhizas; 14C-photoassimilates were supplied to cortex, Hartig net and the mantle of hyphae surrounding the rootlet. Nutrient solution containing sugars (malt extract, glucose) enhanced the growth of the fungus. As a consequence, 14C-photoassimilates from the seedling were accumulated in the mantle, but defence mechanisms of the host cannot be excluded. When soluble nitrogen was omitted from the nutrient solution and replaced by chitin precipitated on the filter-bearing mycorrhizas, the fungus appeared strongly labelled in the mantle, where the fungal chitinase provided soluble nitrogen compounds, necessary for the growth of the seedling.
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    Proliferated seed cones and pollen cones in young black spruce (1991)
    Springer
    Trees 5 (1991), S. 65-74 
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    ISSN: 1432-2285
    Keywords: Developmental plasticity ; Seed-cone proliferation ; Pollen-cone proliferation ; Morphological diversity ; Proliferated cone production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The number of proliferated seed cones (PSc) and proliferated pollen cones (PPc) borne by young plantation-grown Picea mariana (Mill.) B.S.P. was established for trees aged 9–17 years from seed. A description and composition of a range of morphological forms of proliferations were produced. Through paired-comparison analyses, compositions of PSc and PPc were compared to those of nearby non-proliferated cones or to vegetative shoots. Between 41% and 88% of trees of different ages that bore seed cones also bore some PSc; 17–58% with pollen cones also had PPc. The total number of PSc represented 2.3–20% of total numbers of seed cones and PSc at each tree age; PPc represented 1.5–5.8% of the total. Proliferated seed cones were greatly diversified in forms ranging from only a few distal needle-like bracts to mainly needles with a few needle-like bracts. A similar range of diversity existed for PPc. Proliferations involving production of distal needles went on to produce a terminal bud. The diversity of morphological forms and their variable occurrence encountered in this study indicate that the developmental pathway of an apical meristem, although defined somewhat by differentiation, has a degree of flexibility. Manifestation of this developmental flexibility throughout a wild population indicates that this phenomenon may be a normal event in P. mariana.
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    URL: http://dx.doi.org/10.1007/BF00227487
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    Fluoride effects on leaf cell ultrastructure of olive trees growing in the vicinity of the Aluminium Factory of Greece (1991)
    Springer
    Trees 5 (1991), S. 83-89 
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    ISSN: 1432-2285
    Keywords: Air pollutants ; Chloroplasts ; Fluoride ; Olive tree leaves ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Leaves of olive trees growing in the vicinity of the Aluminium Factory of Greece were ultrastructurally investigated in order to determine any malformations caused by environmental air pollutants, especially hydrogen fluoride, in comparison with control samples and normal seasonal senescence. Estimation of some elements accumulated by these leaves showed that they contained high amounts of F and Al attributable to the operation of the nearby factory. The most seriously effected cell components were found to be the mesophyll chloroplasts that show a dilation of the intrathylakoid space, increase of the number of plastoglobuli, discoloration of plastoglobuli, accumulation of large starch grains and an overall disorganized appearance of the organelle. The nuclear crystalloid inclusions have unusual shapes, while the vacuoles contain a fibrillar/granular material that increases their electron density. It is concluded that the ultrastructural malformations are caused by a combination of environmental stresses and air pollutants.
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    URL: http://dx.doi.org/10.1007/BF00227489
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    Quantitative and localized element analysis in cross-sections of spruce [Picea abies (L.) Karst.] needles with different degrees of damage (1991)
    Springer
    Trees 5 (1991), S. 95-100 
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    ISSN: 1432-2285
    Keywords: Element content ; Element distribution ; Forest decline ; Micro-PIXE ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Proton-induced X-ray microanalysis (micro-PIXE) permits the simultaneous determination of the content and the distribution of elements with atomic numbers higher than Z = 13 in biological samples. This method was used to investigate element content and localization in cross-sections of 6-month-old spruce needles. It was possible to detect the elements silicon, phosphorus, sulphur, chlorine, potassium, calcium, manganese, iron and zinc in semithin (10 μm) sections of the needles. The localization of the cationic elements like potassium, calcium and manganese was determined in the one-dimensional line scan mode and in the two-dimensional raster scan mode. To demonstrate the usefulness of this method for forest decline research, element content and localization were compared in needles from two trees, which differed in their degree of damage. We were able to detect differences in the amount of cations and in their distribution inside the needles.
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    Changes in hydraulic conductivity upon freezing of the xylem of Populus x canadensis Moench “robusta” (1991)
    Springer
    Trees 5 (1991), S. 117-121 
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    ISSN: 1432-2285
    Keywords: Freezing stress ; Hydraulic conductivity ; Populus ; Vessels ; Water conduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The impact of freezing stress on the hydraulic conductivity was studied in 4- to 6-year-old branches of Populus x canadensis Moench “robusta” under gravity flow conditions. In fresh branch segments, the hydraulic conductivity was approximately 3–6×10-2 1 h-1kPa-1m and the specific conductivity approximately 22 1 h-1kPa-1m-1. Depending on the gas content of the solutions fed to the xylem of the segments, their hydraulic conductivity was lowered by a freezing-thawing cycle by 20–50%. However, full recovery of hydraulic conductivity was found after about 2 days. Degassed solutions in contrast showed no impediment to flow after the same treatment. The results give evidence, firstly, that the harmful effect of freezing on functioning of water conducting elements is due to the formation of bubbles in xylem sap containing gas in solution, and secondly, that recovery from this impediment is possible in microporous vessels within a period of about 2 days.
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    URL: http://dx.doi.org/10.1007/BF00227494
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    Preformed and neoformed extension of shoots and sylleptic branching in relation to shoot length in Tsuga canadensis (1991)
    Springer
    Trees 5 (1991), S. 107-116 
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    ISSN: 1432-2285
    Keywords: Architectural model ; Eastern hemlock ; Leaf distribution ; Patterns of vigour ; Shoot development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Shoot systems developed over 3 successive years were investigated on 55 understorey Tsuga canadensis (L.) Carr. trees. Paired comparisons of preformed-leaf content of terminal buds and numbers of leaves produced on new shoots showed that neoformed leaves were produced in large numbers. Parent-shoot character was not useful in predicting numbers of preformed leaves, was better related to total leaves produced, but left the majority of the variation unexplained. This reflected the capacity of any terminal bud to produce a shoot with more or less neoformation, depending on conditions for growth. All shoots over 6 cm long produced sylleptic shoots that bore from two to many leaves and were arranged in a mesitonic pattern along the parent. Some of the longer sylleptic shoots produced lateral buds or second-order sylleptic shoots. Monopodial second-year extensions of sylleptic-shoot axes followed an acrotonic pattern, as did proleptic shoots from the few lateral buds borne on the parent shoots. Such lateral buds were more frequent on shorter parent shoots: they typically occurred near the proximal and distal ends. Duration of shoot extension was positively correlated with shoot length: terminal buds became evident as shoot extension neared cessation.
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    URL: http://dx.doi.org/10.1007/BF00227493
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    Function of spiral grain in trees (1991)
    Springer
    Trees 5 (1991), S. 125-135 
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    ISSN: 1432-2285
    Keywords: Transport ; Strength ; Fiber deviations ; Cambial growth ; Reorientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Through spiral grain, conduits for sap lead from each root to all branches. This uniform distribution of sap is indicated by the paths of vessels and tracheids, and has been proven experimentally by means of dyed sap injected into the base of stems or taken up by roots. Trees receiving water only from roots at one side of the root collar nevertheless stay green and continue growing. Spiral grain in bark distributes food from each branch to other flanks of the stem and to most roots. Experimental interruptions of the sap and food conduits caused the cambial zone to reorient new conduit cells in new directions, bypassing the interruption. In particular, spiral grooves cut into the stem surface caused spiral grain. The new cells reorient through division and growth. Although spiral grain is largely under genetic control, trees appear to have a spiral grain especially where needed for distribution of water when root spheres are dry at one side. Compared with straight-grained trees, spiral-grained stems and branches bend and twist more when exposed to strong wind, in this way offering less wind resistance and being less likely to break. Through the bending and twisting, snow slides down from branches rather than breaking them, but the main function of spiral grain is the uniform distribution of supplies from each root to all branches, and from each branch to many roots.
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    Occurrence of unidentified bodies that resemble “plastid initials” in poplar cells after breaking of dormancy in midwinter (1991)
    Springer
    Trees 5 (1991), S. 143-148 
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    ISSN: 1432-2285
    Keywords: Amyloplast ; Dormancy ; Plastid initial ; Plastid proliferation ; Poplar cortical cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Electron-microscopic studies of plastids in cortical cells of poplar (Populus euramericana cv. gelrica) were carried out to examine whether any structural changes were initiated after breaking of dormancy in midwinter under non-growing conditions. After the breaking of dormancy, ultrastructural changes became evident and the profiles of plastids became heterogeneous. Organelles resembling the “plastid initials” proposed by Mühlenthaler and Frey-Wyssling in 1965 were frequently observed concomitant with changes in the plastid envelope. The formation of “plastid initials” appeared to be initiated by the formation of septa in pre-existing plastids. After this stage, narrow connections appeared between the “initials” and the parent plastids. Approximately 50 days after the breaking of dormancy in late March, further heterogeneity in the profiles of plastids was observed. At this stage, young plastids (plastids without starch granules) were frequently observed and the formation of “plastid initials” was hardly ever observed. These observations suggest that the “plastid initials” may be present for only a limited period in the cortical cells of the poplar and may be the precursors of the proplastids. Similar ultrastructural profiles were found in cortical cells of mulberry and in leaf buds of apple trees, suggesting that such changes in the ultrastructure of plastids are a general feature of perennials.
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    Crown profile of foliage area characterized with the Weibull distribution in a hinoki (Chamaecyparis obtusa) stand (1991)
    Springer
    Trees 5 (1991), S. 149-152 
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    ISSN: 1432-2285
    Keywords: Foliage area profile ; Chamaecyparis obtusa (Sieb, et Zucc.) Endl ; Weibull distribution ; Shape parameter ; Scale parameter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Thirten sample trees of various sizes in a 29-year-old hinoki [Chamaecyparis obtusa (Sieb, et Zucc.) Endl.] plantation were felled and subjected to the stratified clip technique. Crown profile of foliage area fitted well with the Weibull distribution. The crown profile tended to be more skewed toward the top of crowns in smaller trees than in larger trees. This tendency was reflected in the value of the shape parameter of the Weibull distribution. The shape parameter ranged from 1.73 to 3.23 and gradually increased up to an asymptotic value with an increase of stem diameter at breast height. The scale parameter of the distribution ranged from 1.0 to 4.2 and tended to increase in proportion to stem diameter at breast height. Foliage area of a tree correlated well with stem diameter at breast height through an ordinary allometric equation. Tree height could be approximated fairly well by a generalized allometric equation as a function of stem diameter at breast height. On the basis of the census of stem diameter at breast height, canopy profile could be constructed synthesizing crown profiles of foliage area for individual trees in the stand. Leaf area index was estimated to be 6.6 ha ha−1.
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    A survey of seasonal bark proteins in eight temperate hardwoods (1991)
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    Trees 5 (1991), S. 153-157 
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    ISSN: 1432-2285
    Keywords: Bark proteins ; Nitrogen storage ; Hardwoods ; Overwintering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Bark proteins of eight temperate hardwoods were analyzed by SDS-PAGE at monthly intervals to determine whether an accumulation of specific proteins, potential storage proteins, occurred in the fall at the time of leaf senescence. Storage proteins were identified as proteins that accumulated during the fall and were present in reduced amounts in the summer. Total protein levels were higher in the winter than in the summer in Fagus sylvatica, Fraxinus americana, Tilia americana, Alnus glulinosa, Betula papyrifera and Querus rubra, but not in Gleditsia triacanthos or Robinia pseudoacacia. Betula contained the most abundant storage protein, although in all species minor bands, which fluctuated seasonally, could be identified. With the exception of Alnus and Betula, results generally correlated with previous microscopy studies of these tree species, which showed varying amounts of protein storage vacuoles present in phloem parenchyma cells during the winter, but not during the summer.
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    Tree vigor and height growth in Black Spruce (1991)
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    Trees 5 (1991), S. 158-163 
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    ISSN: 1432-2285
    Keywords: Specific volume increment ; Waring vigor estimates ; Site quality ; Sapwood respiration ; Photosynthate availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The relationship between tree height and tree vigor was examined in order to test the hypothesis that increased height results in a reduction in photosynthate availability for growth due to an increase in respiratory load of the sapwood. Various vigor indices were measured on black spruce [Picea mariana (Mill.) B. S. P.] trees on a wide range of sites and ages. The relationship between these vigor indices and tree height and site quality were then evaluated through correlation and regression analyses. Vigor indices based on meristematic activity such as specific volume increment and height growth rate were generally more strongly correlated than foliage based indices (i.e. Waring vigor estimates). Both tree height and site index were found to have a significant effect on specific volume increment and height growth rate. However the height effect decreased with a decrease in site quality, and became insignificant (P 〈0.05) on the poorer sites. The full regression model, allowing the height effect to vary between different site quality groups, explained 82% and 72% of the variability in specific volume increment and height growth rate, respectively. The results support the hypothesis that increases in the ratio of respiration to photosynthesis in trees as they increase in size is largely a function of tree height. Possible explanations for the decreased height effect on poor sites are also discussed.
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    Experiments on the water budget of densely and sparsely needled spruces [Picea abies (L.) Karst.] in a declining stand (1991)
    Springer
    Trees 5 (1991), S. 164-170 
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    ISSN: 1432-2285
    Keywords: Forest decline ; Osmotic potential ; Picea abies ; Water content ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The osmotic potentials of needles were compared from numerous trees that had been classified according to needle loss along an altitude profile. With the increasing degree of damage of the trees, the maximum and minimum values deviated more strongly above and below the common mean of all samples. The level of water content of the needles unequivocally reflected the vitality of the trees. Experiments covering a whole vegetation period were performed on a tree pair selected from a natural stand. They were designed to demonstrate differences in water balance between the “healthy” and “damaged” state of the trees. For the “damaged” tree, measurements of the water potentials of single needles showed a greater reduction of potential during the course of the day compared to the “healthy” tree. Recovery in the evenings was slower and often incomplete. The osmotic potentials of “damaged” and “healthy” shoots measured in individual needles also differed both predawn and especially after transpiration stress. Depending on weather and soil desiccation, the differences were more or less pronounced. In the “damaged” tree, the rises in potential after saturation of the twigs fell far short of the “healthy” tree. Reduction of water potential, osmotic potential and relative water content under comparable stress conditions suggest a reduced tolerance of drought by damaged trees. In the context of earlier experiments this result was ascribed to a lack of stomatal control, and long-term pollution effects were thus explained as a specific disturbance of hydroregulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00204339
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    Root responses of flood-tolerant and flood-sensitive tree species to soil redox conditions (1991)
    Springer
    Trees 5 (1991), S. 180-186 
    Details
    ISSN: 1432-2285
    Keywords: Flood-stress ; Root elongation ; Quercus falcata ; Quercus lyrata ; Taxodium distichum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Under controlled rhizotron conditions, roots of Taxodium distichum L., Quercus lyrata Walt, and Q. falcata var. pagodaefolia Ell. were subjected to low soil redox potentials. Root elongation was inhibited at low soil redox potentials. In T. distichum, redox potentials below +200 mV resulted in a significant inhibition of root elongation. In Q. falcata var. pagodaefolia and Q. lyrata, redox potentials below +350 mV resulted in complete cessation of root growth. Studies on root anatomy indicated that low soil redox potenials resulted in a changed cellular structure in the cortex of T. distichum. However, little change was noted in stress roots of oak species. Alcohol dehydrogenase activity in T. distichum roots was approximately doubled compared to control plants, indicating stimulated alcoholic fermentation. In T. distichum, alcoholic fermentation and anatomical changes contribute to flood tolerance but oak species lack these characteristics.
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    URL: http://dx.doi.org/10.1007/BF00204341
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    The effect of two growth forms of Norway spruce on stand development and radiation interception: a model analysis (1991)
    Springer
    Trees 5 (1991), S. 171-179 
    Details
    ISSN: 1432-2285
    Keywords: Biomass ; Computer simulation ; Picea abies ; Stand dynamics ; Tree architecture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Development of tree and canopy structure, and interception of photosynthetically active radiation (PAR) were studied in two model stands of Norway spruce consisting of trees with rapid versus slow site capture. The tree models were derived using Burger's (1953) sample tree material, from which two subpopulations of dominant trees were selected using the rate of horizontal site capture of the tree crowns as the criterion of division. The development of stand structure and interception of PAR were simulated in the two model canopies. The simulation period covered the period from tree age 15–80 years. The average development of the trees in the two subpopulations proved to be very different. The rapidly expanding trees were characterized by low mean within-crown needle area density and a long crown. The slowly expanding trees were smaller but had a higher mean within-crown needle area density. Up to approximately 40 years of age the stand of rapidly expanding trees contained more leaf area and intercepted more radiation than the stand of slowly expanding trees, when canopy cover was held constant. After 40 years of age this relationship was reversed due to the subsequent decline of leaf area in the stand of rapidly expanding trees and the increase in leaf area in the stand of slowly expanding trees. The biological relevancy and silvicultural implications of the simulated patterns of tree and stand development are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00204340
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    Food reserves of Scots pine (Pinus sylvestris L.) (1991)
    Springer
    Trees 5 (1991), S. 187-195 
    Details
    ISSN: 1432-2285
    Keywords: Food reserves ; Pinus sylvestris ; Starch ; Sugars ; Triacylglycerol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The amounts of starch, soluble sugars, triacylglycerols, diacylglycerols and free fatty acids were studied in Scots pine (Pinus sylvestris L.) during an annual cycle in current-year needles and in 1-, 2- and 3-year-old needles collected shortly after bud break. Determination of the compounds was performed using specific enzymatic assays, capillary gas chromatography and thin layer chromatography. Newly emerging needles contained relatively large amounts of starch, but only trace amounts of fat. During autumn and winter, fat content rose, while starch content decreased; amounts of both these reserve materials were very high the next spring shortly before bud break and decreased again during shoot elongation. Concentration of intermediates in triacylglycerol biosynthesis (diacylglycerols and free fatty acids), were low in summer and high in winter. The same pattern was observed for fructose and glucose (the predominant soluble sugars), galactose/arabinose and raffinose/melibiose. In contrast, sucrose concentrations were highest in spring and in autumn. Mature needles of different ages collected in May showed significant differences only in their triacylglycerol and starch content. Concentration changes of reserve materials are discussed in relation to season, mobilization and translocation processes, dormancy, frost resistance and the possibility of carbohydrate-fat interconversions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227524
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  • 89
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    Protein-storing vacuoles in inner bark and leaves of softwoods (1991)
    Springer
    Trees 5 (1991), S. 196-202 
    Details
    ISSN: 1432-2285
    Keywords: Protein-storage vacuole ; Protein body ; Softwoods ; Nitrogen storage ; Overwintering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The seasonal occurrence of protein-storage vacuoles in parenchyma cells of the inner bark and leaf tissues of seven softwood species was examined. Previously published results showed that these organelles often fill the phloem parenchyma cells of the inner bark tissues in overwintering hardwoods, whereas they are absent from this tissue during the summer. We hypothesize that the organelles are involved in the storage of reduced nitrogen during wintering, in a manner analogous to protein bodies of seeds. A survey of the phloem and cambial parenchyma tissues in six evergreen softwood species (Pinus strobus, P. sylvestris, Picea abies, P. glauca, Abies balsamea, and Thuja occidentalis) and in one deciduous softwood species (Larix decidua) was conducted. There was a large variation in the degree and timing of protein-storage vacuole formation between the individual genera and species. The organelles were not seen in summer samples of inner bark tissues of any of the genera or species examined. Protein-storage vacuoles were common in the bark tissues of Pinus, Abies and Thuja, occasionally seen in Picea, and rarely found in Larix during the winter. One-year-old leaves were also examined, since in all but Larix they are overwintering structures and can act as potential sites of nitrogen storage. Protein-storage vacuoles were present in Pinus and Thuja leaf tissue in both summer and winter, in Abies during winter only, and were absent from Picea leaf tissue at all times. These results indicate that the formation of protein-storage vacuoles prior to overwintering is not a ubiquitous phenomenon in softwoods.
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    URL: http://dx.doi.org/10.1007/BF00227525
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    Formation of heartwood substances in the stem of Robinia pseudoacacia L. (1991)
    Springer
    Trees 5 (1991), S. 203-207 
    Details
    ISSN: 1432-2285
    Keywords: Chalcone synthase ; Heartwood extractives ; Phenylalanine ammonia-lyase ; Robinia pseudoacacia L. ; Sapwood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The activities of two key enzymes in flavonoid biosynthesis, phenylalanine ammonia-lyase (PAL, E.C. 4.3.1.5) and chalcone synthase (CHS, E.C. 2.3.1.74) were determined in the trunkwood of Robinia pseudoacacia L. The trees under investigation were cut at different times of the year (September, November, January and April). At all times PAL is active, both in the youngest wood layer (the outermost growth ring) and at the sapwood heartwood boundary. On the other hand, CHS is active exclusively in the vicinity of the heartwood boundary. The results indicate that PAL is involved both in the formation of lignin (outermost annual ring), and in flavonoid biosynthesis (heartwood boundary). Highest activity of both PAL and CHS could be measured at the sapwood heartwood boundary in the tree felled in November, indicating that heartwood formation was occurring mainly at that time. The flavonoids accumulated in the heartwood are obviously formed in situ and seem to be transported only to a minor extent — if at all — via the phloem and the ray cells to the heartwood.
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    URL: http://dx.doi.org/10.1007/BF00227526
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    Growth patterns and bending mechanics of branches (1991)
    Springer
    Trees 5 (1991), S. 232-238 
    Details
    ISSN: 1432-2285
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227530
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    Influence of needle loss, yellowing and mineral content on monoterpenes in the needles of Picea abies (L.) Karst. (1991)
    Springer
    Trees 5 (1991), S. 208-214 
    Details
    ISSN: 1432-2285
    Keywords: Bavaria ; Disease ; Needle ; (Mono)terpenes ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Monoterpenes in needles of Picea abies (L.) Karst. were studied to reveal whether or not the symptoms of forest decline observed in three mountain regions of South Germany (Bavaria) — needle loss and needle yellowing — are related to changes in the amounts of all or individual terpenes. The nutrient supply of the needles was examined in addition to the terpene concentrations, since the disease symptom montane yellowing is often associated with mineral deficiency. At two of the eight locations, trees exhibited Mg-deficiency, at one location K-deficiency was observed, and at another location the S-content of the needles indicated SO2-pollution. Using various statistical methods of analysis, no correlation was observed between the mineral element content of the needles, the percentage of needle loss and either the absolute or percentile terpene amounts stored within the needles. This finding is independent of needle age, date of sampling and terpene pattern. Concerning needle yellowing, the data show a tendency towards a reduction of the terpene concentrations in needles originating from branches with partly yellow needles compared to needles from exclusively green-needled branches. In spite of the fact that only 2-year-old and older needles show the disease symptom of yellowing, the terpene level is reduced even in still green, juvenile and 1-year-old needles. No terpene was found to be an indicator for early recognition of injury.
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    URL: http://dx.doi.org/10.1007/BF00227527
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    Nitrate levels affect the development of the black locust-Rhizobium symbiosis (1991)
    Springer
    Trees 5 (1991), S. 227-231 
    Details
    ISSN: 1432-2285
    Keywords: Robinia pseudoacacia L. ; Nitrate ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Experiments with black locust (Robinia pseudoacacia L.) seedlings grown under strictly controlled laboratory conditions indicated that the availability of nitrate has a marked impact on nitrogen fixation. When nitrate concentrations were very low, both nodulation and seedling growth were impaired, whereas nitrate concentrations high enough to promote plant growth strongly inhibited symbiotic nitrogen fixation. When nitrate was added to the growth medium after infection, nodulation and nitrogen fixation of the seedlings decreased. This effect was even more marked when nitrate was applied before infection with rhizobia. Higher nitrogen concentrations also reduced nodule number and nodule mass when applied simultaneously with the infecting bacteria. The contribution of symbiotic nitrogen fixation to black locust shoot mass by far exceeded its effects on shoot length and root mass. When nitrate availability was very low, specific nitrogen fixation (i. e. nitrogenase activity per nodule wet weight) was improved with increasing nitrogen supply, but rapidly decreased with higher nitrogen concentrations.
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    URL: http://dx.doi.org/10.1007/BF00227529
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    Nitrate reductase in needles, roots and trunk wood of spruce trees [Picea abies (L.) Karst.] (1991)
    Springer
    Trees 5 (1991), S. 215-226 
    Details
    ISSN: 1432-2285
    Keywords: Picea abies ; Nitrate reductase ; Xylem sap ; Fumigation ; Fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nitrate reductase (EC 1.6.6.2) activity (NRA), as measured by an in vivo assay, is present in needle leaves and mycorrhizal fine root tips of adult Norway spruce [Picea abies (L.) Karst.] in at least equal amounts on a fresh weight basis, in both adult and 5-year-old trees. NRA could also be demonstrated in trunk wood of deroted trees after fertilization with 5 mM $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ , exhibiting a longitudinal profile in the trunk. Inducibility in needles can more efficiently be achieved by NO2 (100 μg·m-3) than by 5 mM nitrate, which is effective only in root-amputated trees. A remarkably high level of needle-NRA in unfertilized trees, which are characterized by a very low level of nitrate in the xylem sap, suggests that NRA in spruce needles may in part be constitutive. Organic-N is a major nitrogen source for the needles even in root-amputated trees, indicating pronounced exchange processes between ray parenchyma and trunk xylem, which in turn are modified by the nitrogen source fed to the trunk stump. Intact trees exhibit a very similar amino acid composition of the xylem sap, regardless of whether $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ or $${\text{NH}}_{{\text{4}}^{\text{ + }} }$$ has been fed. The amino acid pattern of the needles is not thrown out of balance by “flooding” with $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ and $${\text{NH}}_{{\text{4}}^{\text{ + }} }$$ , which occurs in fertilized derooted trees. This indicates a distinct potential for homoeostasis of nitrogen entrance-metabolism (i.e. NRA and glutamine synthetase activity) in the needles. In the ectomycorrhiza/fine root-system (EMC), marked differences in NRA were observed depending on root-tip diameter and along the longitudinal profile of the fine roots. EMC-nitrate reductase is strongly enhanced by $${\text{NO}}_{{\text{3}}^{\text{ - }} }$$ . Needle-NRA exhibits a circannual rhythm. An early summer maximum is followed by a December minimum. This activity pattern matches well the transitory increase of soluble nitrogen in spring and the total protein maximum in winter. In an indirect way assimilatory NRA may well contribute to nitrogen overfertilization (by consumption of NOX) as one possible cause of the contemporary decline of spruce populations.
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    URL: http://dx.doi.org/10.1007/BF00227528
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    Small fruit problem in Citrus trees (1991)
    Springer
    Trees 5 (1991), S. 239-243 
    Details
    ISSN: 1432-2285
    Keywords: Citrus sinensis ; Fruit ; Photosynthesis ; Respiration ; Transpiration ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Physiological causes of the small fruit problem which occurs in certain trees of orange [Citrus sinensis (L.) Osbeck cv. Valencia] were investigated in terms of water relations and gas exchange of fruits during early fruit development as well as tree carbohydrate reserves. These data from cv. Valencia trees with and without a small fruit potential were compared with those of the large fruited cv. Navel. Neither fruit water potential nor fruit transpiration nor tree carbohydrate reserves appeared to be a cause of the small fruit. Yield records showed the small fruit to be assocaited with a large number of fruit per tree. However, fruits from cv. Valencia trees with a small fruit potential respired faster than either fruits of the same cultivar and size from trees without the physiological disorder or fruits of the same size of cv. Navel and also exceeded the dark respiration of the respective leaves. Hence, the small fruit problem in cv. Valencia was partly attributed to inefficient fruit photosynthesis, causing excessive respiration of each of a larger number of fruits compared to fruits of a tree of the same cultivar but without the physiological disorder. Fruits of cv. Valencia respired more in their 2 months longer lifetime on the tree relative to those of cv. Navel. It is concluded that orchard management methods will have to be investigated to balance the fruit load of the cv. Valencia tree utilizing the carbon available for fruit growth and to minimise stress during the early fruit development.
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    URL: http://dx.doi.org/10.1007/BF00227531
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    Dormancy in peach (Prunus persica L.) flower buds (1991)
    Springer
    Trees 5 (1991), S. 244-246 
    Details
    ISSN: 1432-2285
    Keywords: Peach ; Floral buds ; Vegetative buds ; Morphology ; Phenology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Peach buds (floral and vegetative) were periodically collected from midsummer until the spring flowering and sprouted under continuous light, 100% relative humidity and 20–25°C. Treatments with 200 ppm gibberellin A3 (GA3) or chilling (2–4°C for 30 days before planting) were applied. Vegetative buds showed well-defined phenological stages: pre-dormancy, “true dormancy”, and end of dormancy. Both GA3 and chilling treatments shortened the sprouting times of vegetative dormant buds close to those in predormancy. Isolated floral buds were irresponsive under all conditions and did not sprout even with the GA3 or chilling treatments. In a comparative study with buds immediately after collection anatomical analysis demonstrated that vegetative buds were almost completely developed by midsummer/early automn and remained in a resting state until the end of winter. Floral buds developed continuously over the same period. Both types of verticils began to differentiate in midsummer. Sepals and petals developed mainly in late summer, androecious floral parts developed throughout the resting period, while gynoecious floral parts showed differentiation in late winter. The flower was completely formed a few days prior to blossoming. Thus, in isolated peach buds fertile verticils are not sufficiently developed during the resting time to allow sprouting.
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    URL: http://dx.doi.org/10.1007/BF00227532
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    Net assimilation rate and shoot area development in birch (Betula pendula Roth.) at different steady-state values of nutrition and photon flux density (1992)
    Springer
    Trees 6 (1992), S. 1-6 
    Details
    ISSN: 1432-2285
    Keywords: Nitrogen ; Photon flux density ; Growth ; Betula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Small birch plants (Betula pendula Roth.) were grown in a climate chamber at different, exponentially increasing rates of nitrogen supply and at different photon flux densities. This resulted in treatments with relative growth rate equal to the relative rate of increase in nitrogen supply and with different equilibrium values of plant nitrogen concentration. Nitrogen productivity (rate of dry matter increase per plant nitrogen) was largely independent of nitrogen supply and was greater at higher photon flux density. Leaf weight ratio, average specific leaf area (and thus leaf area ratio) were all greater at better nitrogen supply and at lower values of photon flux density. The dependencies were such that the ratio of total projected leaf area to plant nitrogen at a given photon flux density was similar at all rates of nitrogen supply. The ratio was greater at lower values of photon flux density. At a given value of photon flux density, net assimilation rate and net photosynthetic rate per shoot area (measured at the growth climate) were only slightly greater at better rates of nitrogen supply. Values were greater at higher photon flux densities. Acclimation of the total leaf area to plant nitrogen ratio and of net assimilation rate was such that nitrogen productivity was largely saturated with respect to photon flux density at values greater than 230 μmol m-2 s-1. At higher photon flux densities, any potential gain in nitrogen productivity associated with higher net assimilation rates was apparently offset by lower ratios of total leaf area to plant nitrogen.
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    URL: http://dx.doi.org/10.1007/BF00224491
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    The effects of water and multi-nutrient stress on xylem sap chemistry, photosynthesis and transpiration of seedlings of two Eucalypts (1992)
    Springer
    Trees 6 (1992), S. 7-12 
    Details
    ISSN: 1432-2285
    Keywords: Eucalyptus ; Nutrients ; Photosynthesis ; Transpiration ; Xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Ten seedlings each of Eucalyptus kitsoniana Maiden and Eucalyptus globulus Labill. were subjected to two levels of water stress and two levels of nutrient stress (macro and micro-nutrients) in a greenhouse for 3 weeks. The objectives were to determine the degree to which seedlings show differences in sap chemistry, photosynthesis and transpiration that relate to the environments in which these two species live. Whole plants were then extracted for xylem sap using a pressure chamber and the sap was analyzed for 14 elements using an inductively coupled plasma spectrometer and a nitrometer. For E. kitsoniana water and nutrient stress, applied separately or in combination, significantly reduced leaf conductance, transpiration, photosynthesis and midday water potential. Nutrient stress alone had less effect than water stress on most functions measured. Water stress alone reduced the root/shoot ratio; the combination of water and nutrient stress increased the root/shoot ratio, primarily because of reduced shoot weight. In E. kitsoniana, water stress alone or in combination with nutrient stress increased the xylem sap concentrations of B and Si. Multi-nutrient stress alone, or in combination with water stress, significantly decreased sap Zn and K. For this species, sap N was decreased by nutrient stress, but increased by water stress. E. globulus had significantly lower transpiration rates and less root mass than E. kitsoniana. Slightly lower leaf conductance and photosynthesis were not significant in E. globulus compared to E. kitsoniana. Water and nutrient stress reduced conductance, transpiration (except for nutrient stress) and photosynthesis, and the effects of water stress on E. globulus were greater than the effects of nutrient stress. Midday water potential was reduced by water stress. Water or nutrient stress alone did not alter seedling root/shoot ratio, but the combination of water and nutrient stress significantly increased the root/shoot ratio for both species. For E. globulus, sap concentrations of Mn, Na, Si and K were increased by water stress (alone or in combination with nutrient stress). Sap N increased with water stress or combined stresses, but decreased under nutrient stress alone. When the two species were compared, E. globulus generally had lower or similar nutrient concentrations in the sap, with Ca, Mg, Mn and P significantly lower than in E. kitsoniana. Seedlings of these two species show strong site adaptations to water and nutrient availability.
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    URL: http://dx.doi.org/10.1007/BF00224492
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    In vivo pH measurement in the xylem of broad-leaved trees using ion-sensitive field-effect transistors (1992)
    Springer
    Trees 6 (1992), S. 13-18 
    Details
    ISSN: 1432-2285
    Keywords: pH value ; Broad-leaved trees ; Xylem ; ISFET ; Sensor ; pH measurement ; Long-term measurement ; In vivo measurement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A new method of in vivo pH determination in the xylem of broad-leaved trees using ion-sensitive field effect transistors is developed and its suitability for use is studied. In the first few hours after the sensor had been implanted in the xylem signals could be detected which were generated in response to mechanical damage; particularly strong signal changes are detectable in Populus balsamifera L., Tilia cordata Mill, and Aesculus hippocastanum L. The pH values of the xylem sap extracted from branches corresponded to the values measured by the in vivo method only at certain times. Due to sensor drift the measuring accuracy of long-term experiments lasting up to 3 weeks is restricted. The in vivo measurement of pH in the xylem of poplar branches revealed the ability of the living xylem to buffer the pH of the sap to its own characteristic value.
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    URL: http://dx.doi.org/10.1007/BF00224493
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    Water holdup capacity and residence time of red spruce and balsam fir branches (1992)
    Springer
    Trees 6 (1992), S. 10-27 
    Details
    ISSN: 1432-2285
    Keywords: Throughfall ; Red spruce ; Balsam fir ; Wettability ; Acid precipitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study examined the throughfall dynamics of high-elevation red spruce (Picea rubens Sarg.) and balsam fir [Abies balsamea (L.) Mill.] branches. A site was established at an elevation of 1160 m on Mt. Washington, New Hampshire, USA, and branches were collected from the canopies of mature trees. Throughfall water dynamics of branches collected in September 1988 and March 1989 were determined using a fluorescent tracer in an artificial precipitation apparatus. Water holdup capacities of spruce and fir branches from different canopy positions were similar. Spruce retained more water per unit area than fir. For rain, a three-compartment model that was used to analyze water dynamics showed that the bulk of water initially on the branch experienced very slow turnover, while intercepted water left the branch quickly. There did not appear to be any difference in throughfall dynamics between spruce and fir. Our results suggest that the initial composition of rain and mobilized dry deposition will influence the composition of water in contact with the branch for a relatively long time, as branch water composition will respond slowly to changes in precipitation composition. These predictions require field testing where sequential sampling of throughfall and precipitation occurs on a time scale equivalent to 0.1–0.2 mm of precipitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224494
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