ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Transpiration of trees and forest stands: short and long-term monitoring using sapflow methods (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Global change biology 2 (1996), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: We show that sapflow is a useful tool for studies of water fluxes in forest ecosystems, because (i) it gives access to the spatial variability within a forest stand, (ii) it can be used even on steep slopes, and (iii) when combined with eddy correlation measurements over forests, it allows separation of individual tree transpiration from the total water loss of the stand. Moreover, sapflow techniques are quite easy to implement.Four sapflow techniques currently coexist, all based on heat diffusion in the xylem. We found a good agreement between three of these techniques. Most results presented here were obtained using the radial flow meter (Granier 1985).Tree sapflow is computed as sap flux density times sapwood area. To scale up from trees to a stand, measurements have to be made on a representative sample of trees. Thus, a number of trees in each circumference class is selected according to the fraction of sapwood they represent in the total sapwood area of the stand. The variability of sap flux density among trees is usually low (CV. 10–15%) in close stands of temperate coniferous or deciduous forests, but is much higher (35–50%) in a tropical rain forest. It also increases after thinning or during a dry spell.A set of 5–10 sapflow sensors usually provides an accurate estimate of stand transpiration. Transpiration measured on two dense spruce stands in the Vosges mountains (France) and one Scot's pine plantation in the Rhine valley (Germany) showed that maximum rate was related to stand LAI and to local climate. Preliminary results comparing the sapflow of a stand of Pinus banksiana to the transpiration of large branches, as part of the BOREAS programme in Saskachewan, Canada showed a similar trend.For modelling purposes, tree canopy conductance (gc) was calculated from Penman-Monteith equation. In most experiments, calculated canopy conductance was dependent on global radiation (positive effect) and on vapour pressure deficit (negative effect) in the absence of other limiting factors. A comparison of the vapour pressure deficit response curves of gc for several tree species and sites showed only small differences among spruce, oak and pine forests when including understorey. Tropical rainforests exhibited a similar behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.1996.tb00078.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Carbon isotope discrimination and wood anatomy variations in mixed stands of Quercus robur and Quercus petraea (2001)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 24 (2001), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The two most common oak species in western Europe, Quercus robur and Quercus petraea, display different ecological behaviours, particularly with respect to their responses to drought. The ecophysiological basis of this niche difference is not understood well. Here we test the hypothesis that these two species present distinct water use efficiencies (WUEs), using the carbon isotope discrimination approach. Leaves and 13 dated ring sequences were sampled in 10 pairs of adult trees growing side by side. Carbon isotope composition was measured on cellulose extracts. In addition, relationships between carbon isotope discrimination and wood anatomy were assessed at the tree level. Quercus robur displayed a 1·0‰ larger isotopic discrimination than Q. petraea, and therefore a lower intrinsic WUE (−13%). This interspecific difference of isotopic discrimination was quite stable with time and independent of tree radial growth and climate fluctuations. A strong positive correlation was observed between average tree values of earlywood vessel surface area and 13C isotopic discrimination. This correlation was even higher with 13C of the 1976 dry year (r = 0·86). These observations led to the hypothesis that hydraulic properties of xylem could exert a constraint on leaf gas exchange, resulting in a larger WUE for individuals with smaller vessel cross-section area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0016-8025.2001.00733.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Changes of tree-ring δ13C and water-use efficiency of beech (Fagus sylvatica L.) in north-eastern France during the past century (1998)
    Oxford, UK : Blackwell Science Ltd, UK
    Plant, cell & environment 21 (1998), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We investigated variation in intrinsic water-use efficiency during the past century by analysing δ13C in tree rings of beech growing in north-eastern France. Two different silvicultural systems were studied: high forest and coppice-with-standards. We studied separately effects related to the age of the tree at the time the ring was formed and effects attributable to environmental changes. At young ages, δ13C shows an increase of more than 1‰. However, age-related trends differ in high forest and coppice-with-standards. Changes in microenvironmental variables during stand maturation, and physiological changes related to structural development of the trees with ageing, could explain these results. During the past century, δ13C in tree rings shows a pattern of decline that is not paralleled by air δ13C changes. Isotopic discrimination has significantly decreased from 18·1 to 16·4‰ in high forest and varied insignificantly between 17·4 and 16·9‰ in coppice-with-standards. As a consequence, intrinsic water-use efficiency has increased by 44% in high forest and 23% in coppice-with-standards during the past century. These results accord with the increased water-use efficiency observed in controlled experiments under a CO2-enriched atmosphere. However, other environmental changes, such as nitrogen deposition, may be responsible for such trends.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1998.00304.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Photosynthesis of oak trees [Quercus petraea (Matt.) Liebl.] during drought under field conditions: diurnal course of net CO2 assimilation and photochemical efficiency of photosystem II (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 15 (1992), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Adult trees of Quercus petraea were submitted to controlled water shortage in a natural stand near Nancy, France. Diurnal course of net CO2 assimilation rate (A) was measured in situ together with chlorophyll a fluorescence determined on dark adapted leaves. In 1990, trees experienced a strong water stress, with predawn and midday leaf water potentials below –2·0 and –3·0 MPa, respectively. Diurnal course of A of well-watered trees exhibited sometimes important midday decreases in A related to high temperature and vapour pressure deficit. Decreases in initial (Fo) and maximal (Fm) fluorescence and sometimes in photochemical efficiency of photosystem II (Fv/Fm) were observed and probably revealed the onset of mechanisms for thermal de-excitation. These mechanisms were shown to be sensitive to dithiothreitol. All these effects were reversible and vanished almost completely overnight. Therefore, they may be considered as protective mechanisms adjusting activity of photosystem II to the electron requirement for photosynthesis. Water stress amplified these reactions: A was strongly decreased, showing important midday depression; diurnal reductions in Fm and Fv/Fm were enhanced. The same trends were observed during summer 1991, despite a less marked drought. These protective mechanisms seemed very effective, as no photoinhibitory damage to PS II could be detected in either water stressed or control trees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1992.tb02148.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Soil water dynamics in an oak stand (1995)
    Springer
    Plant and soil 172 (1995), S. 29-43 
    Details
    ISSN: 1573-5036
    Keywords: modelisation ; soil-root interface ; soil water potential ; soil water uptake ; transient state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A model describing water uptake by plants with particular attention to the soil-root interface under transient conditions is derived and discussed. Field data on a daily scale enable the unknown parameters of the model to be determined with the help of an identification technique. The model is then used to analyse the experimental results presented in part I of this paper. The loss of total conductivity of the soil-tree system under drought conditions whereas the metabolism of the trees seems to remain unaffected can be explained by the increase of the soil-root resistance. In fact this resistance becomes the limiting factor when the volumetric soil water content decreases (below θ=0.33 for the superficial layer and 0.36 for the deeper one in the studied case). Such values can be frequently encountered at the end of summer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020857
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Soil water dynamics in an oak stand (1995)
    Springer
    Plant and soil 172 (1995), S. 17-27 
    Details
    ISSN: 1573-5036
    Keywords: drought ; in situ ; leaf water potential ; Quercus petraea ; Quercus robur ; soil water ; soil water potential ; soil water uptake ; root
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil water dynamics under a mixed stand of mature sessile and pedunculate oaks were studied both under natural conditions and during imposed water shortages in a lysimeter. Root densities of each species were described in situ by counting roots in the trench surrounding the dry plot. Soil water contents and potentials, and pre-dawn leaf water potentials (Ψwp) were monitored during three successive years. Soil water retention characteristics were obtained from field measurements of water potential and water content. The decreasing rooting density with depth was strongly related to soil physical properties. The root system was separated into two compartments by a layer with a high clay content. The deepest soil compartment was mainly explored by fine roots. Neutron probe measurements allowed the detection of variations in water content down to a depth of 2.00 m. The distribution of water uptake among the different soil layers changed when drought increased. Water was extracted from the deepest reservoir, and capillary rises even occurred after partial water depletion in the upper part of the soil. Seasonal trends of pre-dawn leaf water potential generally matched those of soil water potential in the wettest rooted zone, which was at − 140 cm. In the upper, dry, horizons, the sharp loss of soil hydraulic conductivity reduced water transport to roots leading to impossible equilibrium between roots and soil at pre-dawn. Finally, Ψwp presented a low sensitivity to variations of total soil water content between 40% and 100% of extractable water. Below this threshold, Ψwp decreased sharply to a minimal value of about − 2.0 MPa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020856
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    facet.materialart.
    Unknown
    Water transfer in a mature oak stand (Quercuspetraea): seasonal evolution and effects of a severe drought (1993)
    Canadian Science Publishing
    Details
    Publication Date: 1993-06-01
    Description: The reactions of sessile oak (Quercuspetraea (Mattuschka) Liebl.) to drought were studied under natural conditions in a 32-year-old stand near Nancy (northeastern France) during the summers of 1989 (strongly rain deficient) and 1990. A plot of five trees was subjected to imposed water shortage, while a group of irrigated trees was used as a control. Measurements of xylem sap flows and water potential enabled the computation of plot transpiration, canopy conductance, and specific hydraulic conductance in the soil–tree continuum. Stomatal conductance was measured directly with a porometer. Specific hydraulic conductance of our oaks was of the same order of magnitude as that reported for other species. It decreased significantly during spring because of a time lag between cambial growth and leaf area expansion. Measured transpiration was close to potential evapotranspiration, except during days with high vapor pressure deficits, which promoted stomatal closure in the absence of soil water deficits. Imposed drought caused predawn leaf water potentials to reach values as low as −2.0 MPa and a progressive decline in hydraulic conductance, which was probably attributable to modifications in hydraulic properties at the soil–root interface. This gradual decline in conductance was attributed to their deep rooting (1.40 m). This study revealed that Q. petraea may be considered as drought tolerant because of adaptations like deep rooting, efficient and safe xylem sap transport, maintenance of significant stomatal conductance, and significant transpiration, even during strong drought stress.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Is ring width a reliable proxy for stem-biomass increment? A case study in European beech (2005)
    Canadian Science Publishing
    Details
    Publication Date: 2005-12-01
    Description: The relationship between basal-area increment and stem-volume increment or biomass annual production was investigated in 30 dominant European beech (Fagus sylvatica L.) in northeastern France. The trees were sampled at four heights along the stem for dendrochronological and densitometric measurements. Annual stem-volume and stem-biomass increments were computed from the measurements and were not obtained by applying allometric relationships. A comparison of the ring-area increments at the four stem heights indicated that the vertical distribution of annual growth fluctuates at an interannual time step and is influenced by climate during the growing season, particularly drought events. Ring-area increments were more strongly reduced at breast height than in the upper parts of the tree during dry years. Relationships between basal-area increment and volume or annual biomass production were very strong, but the residuals of these relationhips contained up to 50% climate information. The amplitude of the breast-height radial-growth response to drought is much larger than the volume and biomass-production responses. Variations of wood density in this diffuse-porous species are not large enough to consistently modify the estimates of annual stem biomass production. Breast-height series are a valuable tool for dendrochronological investigations, but as they are more sensitive to drought, they greatly underestimate tree biomass increments during drought episodes.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Nitrogen sources for current-year shoot growth in 50-year-old sessile oak trees: an in situ 15N labeling approach (2011)
    Oxford University Press
    Details
    Publication Date: 2011-12-13
    Description: We used long-term in situ 15 N labeling of the soil to investigate the contribution of the two main nitrogen (N) sources (N uptake versus N reserves) to sun shoot growth from bud burst to full leaf expansion in 50-year-old sessile oaks. Recovery of 15 N by growing compartments (leaves, twigs and buds) and presence of 15 N in phloem sap were checked weekly. During the first 2 weeks following bud burst, remobilized N contributed ~90% of total N in growing leaves and twigs. Nitrogen uptake from the soil started concomitantly with N remobilization but contributed only slightly to bud burst. However, the fraction of total N due to N uptake increased markedly once bud burst had occurred, reaching 27% in fully expanded leaves and 18% in developed twigs. In phloem sap, the 15 N label appeared a few days after the beginning of labeling and increased until the end of bud burst, and then decreased at full leaf expansion in June. Of all the shoot compartments, leaves attracted most of the absorbed N, which accounted for 68% of new N in shoots, whereas twigs and new buds accounted for only 28 and 3%, respectively. New N allocated to leaves increased from unfolding to full expansion as total N concentration in the leaves decreased. Our results underline the crucial role played by stored N in rapid leaf growth and in the sustained growth of oak trees. Any factors that reduce N storage in autumn may therefore impair spring shoot growth.
    Print ISSN: 0829-318X
    Electronic ISSN: 1758-4469
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Oxford University Press
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Vulnerability to air embolism of three European oak species (Quercus petraea (Matt) Liebl, Q pubescens Willd, Q robur L) (1992)
    EDP Sciences
    Details
    Publication Date: 1992-01-01
    Print ISSN: 0003-4312
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by EDP Sciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...