The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Christian Korner - One of the best experts on this subject based on the ideXlab platform.
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do the elevational limits of Deciduous Tree species match their thermal latitudinal limits
Global Ecology and Biogeography, 2013Co-Authors: Christophe F Randin, Jens Paulsen, Yann Vitasse, Chris Kollas, Thomas Wohlgemuth, Niklaus E Zimmermann, Christian KornerAbstract:Aim We compared the upper limits of 18 Deciduous Tree species with respect to elevation in Switzerland and latitude in Europe. We hypothesized that species would exhibit the same relative positions along elevation and latitude, which can be expected if species have reached their thermal cold limit along both gradients.
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elevational adaptation and plasticity in seedling phenology of temperate Deciduous Tree species
Oecologia, 2013Co-Authors: Yann Vitasse, Christophe F Randin, Chris Kollas, Gunter Hoch, Armando Lenz, J F Scheepens, Christian KornerAbstract:Phenological events, such as the initiation and the end of seasonal growth, are thought to be under strong evolutionary control because of their influence on Tree fitness. Although numerous studies highlighted genetic differentiation in phenology among populations from contrasting climates, it remains unclear whether local adaptation could restrict phenological plasticity in response to current warming. Seedling populations of seven Deciduous Tree species from high and low elevations in the Swiss Alps were investigated in eight common gardens located along two elevational gradients from 400 to 1,700 m. We addressed the following questions: are there genetic differentiations in phenology between populations from low and high elevations, and are populations from the upper elevational limit of a species’ distribution able to respond to increasing temperature to the same extent as low-elevation populations? Genetic variation of leaf unfolding date between seedlings from low and high populations was detected in six out of seven Tree species. Except for beech, populations from high elevations tended to flush later than populations from low elevations, emphasizing that phenology is likely to be under evolutionary pressure. Furthermore, seedlings from high elevation exhibited lower phenological plasticity to temperature than low-elevation provenances. This difference in phenological plasticity may reflect the opposing selective forces involved (i.e. a trade-off between maximizing growing season length and avoiding frost damages). Nevertheless, environmental effects were much stronger than genetic effects, suggesting a high phenological plasticity to enable Tree populations to track ongoing climate change, which includes the risk of tracking unusually warm springs followed by frost.
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drought sensitivity ranking of Deciduous Tree species based on thermal imaging of forest canopies
Agricultural and Forest Meteorology, 2011Co-Authors: Daniel Scherrer, Martin K F Bader, Christian KornerAbstract:Most climate change projections for Central Europe predict higher mean summer temperatures and prolonged summer drought periods. However, in diverse mixed forest stands we expect Tree species specific responses to water shortage, as Tree species are highly variable in rooting depth and physiological traits related to the water balance. Here, we assessed the drought sensitivity of the water relations of six Deciduous forest Tree species at four sites with contrasting water availability by airborne thermal imagery of canopy foliage temperature, sap flow and soil water potential. Canopy architecture had a consistent influence on canopy foliage temperature with 'dense canopy' species (Acer pseudoplatanus, Fagus sylvatica and Tilia platyphyllos) being warmer (0.5-1.5 K) than 'open canopy' species (Fraxinus excelsior, Prunus avium and Quercus petraea). While the canopy foliage was close to air temperature at the beginning of the drought period (Delta T(C-A) = -0.1 to 0.7 K) it strongly warmed up with ongoing drought, especially at the two 'dry' sites with a Delta T(C-A) of 3.5-5K. The pronounced canopy foliage warming at the 'dry' sites after 22 days of drought was associated with reduced transpiration rates as sap flow was curtailed by 20-35% in all species except F. excelsior and Q. petraea. Based on canopy foliage temperature and sap flow data, we considered A. pseudoplatanus the most drought sensitive species followed by F. sylvatica, T. platyphyllos and P. avium and the two ring-porous species F. excelsior and Q petraea being clearly the least sensitive ones. At drier sites, increasing summer temperatures and drought might change the competitive abilities of Tree species in favour of those that are able to maintain transpirational fluxes and cooler canopies such as F. excelsior and Q petraea. (C) 2011 Elsevier B.V. All rights reserved.
Mayumi Y Ogasa - One of the best experts on this subject based on the ideXlab platform.
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recovery performance in xylem hydraulic conductivity is correlated with cavitation resistance for temperate Deciduous Tree species
Tree Physiology, 2013Co-Authors: Mayumi Y Ogasa, Naoko Miki, Yuki Murakami, Ken YoshikawaAbstract:Woody species hydraulically vulnerable to xylem cavitation may experience daily xylem embolism. How such species cope with the possibility of accumulated embolism is unclear. In this study, we examined seven temperate woody species to assess the hypothesis that low cavitation resistance (high vulnerability to cavitation) is compensated by high recovery performance via vessel refilling. We also evaluated leaf functional and xylem structural traits. The xylem recovery index (XRI), defined as the ratio of xylem hydraulic conductivity in plants rewatered after soil drought to that in plants under moist conditions, varied among species. The xylem water potential causing 50% loss of hydraulic conductivity (Ψ50) varied among the species studied, whereas only a slight difference was detected with respect to midday xylem water potential (Ψmin), indicating smaller hydraulic safety margins (Ψmin − Ψ50) for species more vulnerable to cavitation. Cavitation resistance (|Ψ50|) was negatively correlated with XRI across species, with cavitation-vulnerable species showing a higher performance in xylem recovery. Wood density was positively correlated with cavitation resistance and was negatively correlated with XRI. These novel results reveal that coordination exists between cavitation resistance and xylem recovery performance, in association with wood functional traits such as denser wood for cavitation-resistant xylem and less-dense but water-storable wood for refillable xylem. These findings provide insights into long-term maintenance of water transport in Tree species growing under variable environmen tal conditions.
Delphis F Levia - One of the best experts on this subject based on the ideXlab platform.
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seasonal and meteorological effects on differential stemflow funneling ratios for two Deciduous Tree species
Journal of Hydrology, 2014Co-Authors: Courtney M Siegert, Delphis F LeviaAbstract:Summary Stemflow is an important subcanopy flux that delivers enriched rainfall to soils immediately surrounding a Tree. Stemflow volume represents the quantity of this hydrologic flux while funneling ratio (FR) represents the efficiency with which individual Trees scavenge water during rainfall events. Stemflow hydrology and storm meteorological characteristics were monitored from 2007 through 2012 to determine the interspecific differences in stemflow flux with a focus on FR efficiency. The objective of this study was to examine the influence of Tree species and size on stemflow FR, determine how seasonality affects stemflow FR, and quantify the role of storm meteorological conditions on stemflow FR. The results presented in this paper build upon 2 years of previous hydrologic research from the Fair Hill, MD field site, which strengthen previous findings via larger storm sample size and highlight more complex stemflow hydrologic relationships than originally assumed. Specifically, this study has demonstrated (1) the efficiency with which smaller Trees gain access to rainfall via higher FR than larger Trees, (2) the FR variability of F. grandifolia induced by the species’ ease of generating stemflow under many storm conditions, and (3) the necessity of many years of hydrometeorological sampling to capture long-term rainfall characteristics and trends. The efficiency of smaller Trees to preferentially funnel water to their Tree base has implications for forests undergoing change. Forest disturbance and subsequent regrowth is dominated by smaller Trees, but additional research is necessary to understand how saplings compete among one another to gain access to stemflow and how this may be influenced by changing climates and forest composition.
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interspecific variation of bark water storage capacity of three Deciduous Tree species in relation to stemflow yield and solute flux to forest soils
Catena, 2005Co-Authors: Delphis F Levia, Stanley R HerwitzAbstract:Abstract The purpose of the study was to: (1) test if normative bark water storage capacities differed significantly among three co-occurring Deciduous Tree species; and (2) examine the extent to which stemflow production and resulting solute inputs in temperate Deciduous forests are affected by bark water storage capacity. Normative bark water storage capacities were determined for: Betula lenta L. (sweet birch), Carya glabra Mill. (pignut hickory), and Quercus rubra L. (northern red oak). Using the computed normative bark water storage capacities, previously published allometric equations relating Tree diameter to aboveground woody surface area, and stemflow yield and chemistry data from ten precipitation events, the influence of bark water storage capacity on stemflow production and solute inputs was examined. Results demonstrated normative bark water storage capacities differed significantly among the Tree species examined. Quercus rubra was found to hold the most water and B. lenta the least. For a 30 cm diameter Tree, normative bark water storage capacities ranged from approximately 100 l for B. lenta to 250 l for Q. rubra. Despite a higher normative bark water storage capacity, Q. rubra was computed to have the largest stemflow solute inputs. Differences in stemflow quantities as well as solute inputs were attributable to interspecific variation in bark morphology and branching architecture, characteristics that affect amount of storage and detention times. Bark water storage capacity is linked with the geoecology of temperate Deciduous forests because stemflow volume and solute inputs are partly determined by bark water storage capacity.
Ken Yoshikawa - One of the best experts on this subject based on the ideXlab platform.
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recovery performance in xylem hydraulic conductivity is correlated with cavitation resistance for temperate Deciduous Tree species
Tree Physiology, 2013Co-Authors: Mayumi Y Ogasa, Naoko Miki, Yuki Murakami, Ken YoshikawaAbstract:Woody species hydraulically vulnerable to xylem cavitation may experience daily xylem embolism. How such species cope with the possibility of accumulated embolism is unclear. In this study, we examined seven temperate woody species to assess the hypothesis that low cavitation resistance (high vulnerability to cavitation) is compensated by high recovery performance via vessel refilling. We also evaluated leaf functional and xylem structural traits. The xylem recovery index (XRI), defined as the ratio of xylem hydraulic conductivity in plants rewatered after soil drought to that in plants under moist conditions, varied among species. The xylem water potential causing 50% loss of hydraulic conductivity (Ψ50) varied among the species studied, whereas only a slight difference was detected with respect to midday xylem water potential (Ψmin), indicating smaller hydraulic safety margins (Ψmin − Ψ50) for species more vulnerable to cavitation. Cavitation resistance (|Ψ50|) was negatively correlated with XRI across species, with cavitation-vulnerable species showing a higher performance in xylem recovery. Wood density was positively correlated with cavitation resistance and was negatively correlated with XRI. These novel results reveal that coordination exists between cavitation resistance and xylem recovery performance, in association with wood functional traits such as denser wood for cavitation-resistant xylem and less-dense but water-storable wood for refillable xylem. These findings provide insights into long-term maintenance of water transport in Tree species growing under variable environmen tal conditions.
Rong Yu - One of the best experts on this subject based on the ideXlab platform.
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An observation-based progression modeling approach to spring and autumn Deciduous Tree phenology
International Journal of Biometeorology, 2016Co-Authors: Rong Yu, Mark D. Schwartz, Alison Donnelly, Liang LiangAbstract:It is important to accurately determine the response of spring and autumn phenology to climate change in forest ecosystems, as phenological variations affect carbon balance, forest productivity, and biodiversity. We observed phenology intensively throughout spring and autumn in a temperate Deciduous woodlot at Milwaukee, WI, USA, during 2007–2012. Twenty-four phenophase levels in spring and eight in autumn were recorded for 106 Trees, including white ash, basswood, white oak, boxelder, red oak, and hophornbeam. Our phenological progression models revealed that accumulated degree-days and day length explained 87.9–93.4 % of the variation in spring canopy development and 75.8–89.1 % of the variation in autumn senescence. In addition, the timing of community-level spring and autumn phenophases and the length of the growing season from 1871 to 2012 were reconstructed with the models developed. All simulated spring phenophases significantly advanced at a rate from 0.24 to 0.48 days/decade ( p ≤ 0.001) during the 1871–2012 period and from 1.58 to 2.00 days/decade ( p
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an observation based progression modeling approach to spring and autumn Deciduous Tree phenology
International Journal of Biometeorology, 2016Co-Authors: Rong Yu, Mark D. Schwartz, Alison Donnelly, Liang LiangAbstract:It is important to accurately determine the response of spring and autumn phenology to climate change in forest ecosystems, as phenological variations affect carbon balance, forest productivity, and biodiversity. We observed phenology intensively throughout spring and autumn in a temperate Deciduous woodlot at Milwaukee, WI, USA, during 2007–2012. Twenty-four phenophase levels in spring and eight in autumn were recorded for 106 Trees, including white ash, basswood, white oak, boxelder, red oak, and hophornbeam. Our phenological progression models revealed that accumulated degree-days and day length explained 87.9–93.4 % of the variation in spring canopy development and 75.8–89.1 % of the variation in autumn senescence. In addition, the timing of community-level spring and autumn phenophases and the length of the growing season from 1871 to 2012 were reconstructed with the models developed. All simulated spring phenophases significantly advanced at a rate from 0.24 to 0.48 days/decade (p ≤ 0.001) during the 1871–2012 period and from 1.58 to 2.00 days/decade (p < 0.02) during the 1970–2012 period; two simulated autumn phenophases were significantly delayed at a rate of 0.37 (mid-leaf coloration) and 0.50 (full-leaf coloration) days/decade (p < 0.01) during the 1970–2012 period. Consequently, the simulated growing season lengthened at a rate of 0.45 and 2.50 days/decade (p < =0.001), respectively, during the two periods. Our results further showed the variability of responses to climate between early and late spring phenophases, as well as between leaf coloration and leaf fall, and suggested accelerating simulated ecosystem responses to climate warming over the last four decades in comparison to the past 142 years.
