89 results on '"Vitasse Y"'
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2. The great acceleration of plant phenological shifts
- Author
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Vitasse, Y., Baumgarten, F., Zohner, C. M., Rutishauser, T., Pietragalla, B., Gehrig, R., Dai, J., Wang, H., Aono, Y., and Sparks, T. H.
- Published
- 2022
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Catalog
3. Letter to the Editor : New guidelines about tetanus vaccination schedules in Europe should be evaluated with caution Comment on: Tetanus vaccination, antibody persistence and decennial booster: a serosurvey of university students and at-risk workers. By Borrella-Venturini et al .
- Author
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ELDIN, C., KHALOUTA, H., VITASSE, Y., MILLION, M., and BROUQUI, P.
- Published
- 2017
4. How Do Climate Change Experiments Alter Plot-Scale Climate?
- Author
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Ettinger, A. K, Chuine, I, Cook, B. I, Dukes, J. S, Ellison, A. M, Johnston, M. R, Panetta, A. M, Rollinson, C. R, Vitasse, Y, and Wolkovich, E. M
- Subjects
Meteorology And Climatology - Abstract
To understand and forecast biological responses to climate change, scientists frequently use field experiments that alter temperature and precipitation. Climate manipulations can manifest in complex ways, however, challenging interpretations of biological responses. We reviewed publications to compile a database of daily plot-scale climate data from 15 active-warming experiments. We find that the common practices of analysing treatments as mean or categorical changes (e.g. warmed vs.unwarmed) masks important variation in treatment effects over space and time. Our synthesis showed that measured mean warming, in plots with the same target warming within a study, differed by up to 1.6° Celsius degrees (63% of target), on average, across six studies with blocked designs. Variation was high across sites and designs: for example, plots differed by 1.1°Celsius degrees (47% of target) on average, for infrared studies with feedback control (n = 3) vs. by 2.2° Celsius degrees (80% of target) on average for infrared with constant wattage designs (n = 2). Warming treatments produce non-temperature effects as well, such as soil drying. The combination of these direct and indirect effects is complex and can have important biological consequences. With a case study of plant phenology across five experiments in our database, we show how accounting for drier soils with warming tripled the estimated sensitivity of budburst to temperature. We provide recommendations for future analyses, experimental design,and data sharing to improve our mechanistic understanding from climate change experiments, and thus their utility to accurately forecast species' responses. more...
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- 2019
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5. European beech dieback after premature leaf senescence during the 2018 drought in northern Switzerland
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Frei, E. R., primary, Gossner, M. M., additional, Vitasse, Y., additional, Queloz, V., additional, Dubach, V., additional, Gessler, A., additional, Ginzler, C., additional, Hagedorn, F., additional, Meusburger, K., additional, Moor, M., additional, Samblás Vives, E., additional, Rigling, A., additional, Uitentuis, I., additional, von Arx, G., additional, and Wohlgemuth, T., additional more...
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- 2022
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6. Unrestricted quality of seeds in European broad-leaved tree species growing at the cold boundary of their distribution
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Kollas, C., Vitasse, Y., Randin, C. F., Hoch, G., and Körner, C.
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- 2012
7. Are plant pathogen populations adapted for encounter with their host? A case study of phenological synchrony between oak and an obligate fungal parasite along an altitudinal gradient
- Author
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DESPREZ-LOUSTAU, M.-L., VITASSE, Y., DELZON, S., CAPDEVIELLE, X., MARÇAIS, B., and KREMER, A.
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- 2010
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8. Rôle des interactions plante-plante dans la réponse des forêts au changement climatique : l’exemple des forêts de chêne sessile et de hêtre dans les Pyrénées Occidentales
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Michalet, Richard, Vitasse, Y, Delzon, Sylvain, Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut de géographie, Université de Neuchâtel (UNINE), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Biodiversité, Gènes & Communautés (BioGeCo), and Institut National de la Recherche Agronomique (INRA)-Université de Bordeaux (UB) more...
- Subjects
gradient altitudinal ,changement climatique ,[SDV]Life Sciences [q-bio] ,heat resource ,phenology ,phénologie ,facilitation ,climate change ,altitudinal gradient ,ressource ,compétition ,quantité de chaleur ,competition ,growing degree days - Abstract
Ce numéro d’Innovations Agronomiques rassemble les présentations du colloque « Adaptation des forêts méditerranéennes aux changements climatiques » qui s'est tenu en Avignon le 20 novembre 2015.; National audience; Researches on climate change effects in forests, including species distribution and phenological models, ignore plant-plant interactions. The goal of this paper is to assess the mediating role of plantplant interactions in the response of sessile oak and common beach to climate change in the western Pyrenees (France). Preliminary studies suggested that important differences in phenological sensitivity to warming among the two species might explain their current altitudinal distribution and alter their competitive balance under climate change. We present here the results of an in situ experiment which aims at quantifying variation in interactions between seedlings of the two species and adult trees along an altitudinal gradient. Results for survival showed that competition strongly increased with increasing elevation, but for oak only. The lack of heat below the shaded canopy of the high elevation beech forests currently limits the length of the growing season for oak, impeding its dominance at high elevation. Climate warming should decrease competition for oak as compared to beech considering the higher phenological sensitivity to warming of oak. This competitive release should exacerbate climate change effects on the altitudinal migration of the two species.; Les recherches concernant l’impact du changement climatique sur les forêts, telles que les modèles d’enveloppes climatiques et les modèles phénologiques, ignorent les interactions biotiques. Notre objectif est l’étude du rôle médiateur des interactions chêne-hêtre dans leur réponse au changement climatique dans les Pyrénées Occidentales. Des études préliminaires suggèrent que des différences importantes de sensibilité phénologique à la température entre ces espèces pourraient expliquer leur répartition altitudinale actuelle et l’évolution de leur balance compétitive avec le changement climatique. Nous présentons ici les résultats d’une expérimentation réalisée in situ et ayant pour but de quantifier les variations d’interactions entre des plantules de ces deux espèces et les arbres adultes le long d’un gradient altitudinal. Les résultats pour la survie des plantules montrent une augmentation importante de la compétition en altitude pour le chêne seulement. C’est le manque de chaleur à l’ombre du hêtre à haute altitude qui limite actuellement la longueur de la saison de végétation du chêne et sa progression en altitude. Le réchauffement climatique devrait diminuer la compétition subie par le chêne relativement au hêtre de par sa plus grande sensibilité phénologique à la température et ainsi exacerber les effets du changement climatique sur la migration altitudinale de ces deux espèces. more...
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- 2015
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9. Earlier leaf-out rather than difference in freezing resistance puts juvenile trees at greater risk of freeze damage than adult trees
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Vitasse, Y, Lenz, A, and Hoch, G. & Kxf6rner, C.
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- 2014
10. How accurate can weather stations predict temperatures at tree species limits?
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Kollas, C, Randin, C.F, and Vitasse, Y. & Kxf6rner, C.
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- 2014
11. Is the use of cuttings a good proxy to explore phenological responses of temperate forests in warming and photoperiod experiments?
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Vitasse, Y., primary and Basler, D., additional
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- 2014
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12. Unrestricted quality of seeds in European broad-leaved tree species growing at the cold boundary of their distribution
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Kollas, C., primary, Vitasse, Y., additional, Randin, C. F., additional, Hoch, G., additional, and Korner, C., additional
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- 2011
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13. To what extent is altitudinal variation of functional traits driven by genetic adaptation in European oak and beech?
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Bresson, C. C., primary, Vitasse, Y., additional, Kremer, A., additional, and Delzon, S., additional
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- 2011
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14. Enquête de satisfaction des usagers d'un SAU adulte. Intérêts et limites d'une étude prospective
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Attard, N., primary, Vitasse, Y., additional, Nouvellet, S., additional, Kurtzemann, I., additional, Pisapia, M., additional, Galiez, F., additional, Gentile, S., additional, and Alazia, M., additional more...
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- 2007
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15. Unprecedented risk of spring frost damage in Switzerland and Germany in 2017
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Vitasse, Y and Rebetez, M
16. Increase in the risk of exposure of forest and fruit trees to spring frosts at higher elevations in Switzerland over the last four decades
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Vitasse, Y, Schneider, L, Rixen, C, Christen, D, and Rebetez, M
17. A first assessment of the impact of the extreme 2018 summer drought on Central European forests
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Schuldt, B., Buras, A., Arend, M., Vitasse, Y., Beierkuhnlein, C., Damm, A., Gharun, M., Grams, T. E. E., Hauck, M., Hajek, P., Hartmann, H., Hiltbrunner, E., Hoch, G., Holloway-Phillips, M., Körner, C., Larysch, E., Lübbe, T., Nelson, D. B., Rammig, A., Rigling, A., Rose, L., Ruehr, N. K., Schumann, K., Weiser, F., Werner, C., Wohlgemuth, T., Zang, C. S., and Kahmen, A. more...
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Drought stress ,Tree mortality ,13. Climate action ,Recovery ,Temperate forests ,Water potential ,Vapour pressure deficit ,Climate change ,Hotter drought ,15. Life on land ,Normalized Difference Vegetation Index ,Hydraulic failure - Abstract
In 2018, Central Europe experienced one of the most severe and long-lasting summer drought and heat wave ever recorded. Before 2018, the 2003 millennial drought was often invoked as the example of a “hotter drought”, and was classified as the most severe event in Europe for the last 500 years. First insights now confirm that the 2018 drought event was climatically more extreme and had a greater impact on forest ecosystems of Austria, Germany and Switzerland than the 2003 drought. Across this region, mean growing season air temperature from April to October was more than 3.3°C above the long-term average, and 1.2°C warmer than in 2003. Here, we present a first impact assessment of the severe 2018 summer drought and heatwave on Central European forests. In response to the 2018 event, most ecologically and economically important tree species in temperate forests of Austria, Germany and Switzerland showed severe signs of drought stress. These symptoms included exceptionally low foliar water potentials crossing the threshold for xylem hydraulic failure in many species and observations of widespread leaf discoloration and premature leaf shedding. As a result of the extreme drought stress, the 2018 event caused unprecedented drought-induced tree mortality in many species throughout the region. Moreover, unexpectedly strong drought-legacy effects were detected in 2019. This implies that the physiological recovery of trees was impaired after the 2018 drought event, leaving them highly vulnerable to secondary drought impacts such as insect or fungal pathogen attacks. As a consequence, mortality of trees triggered by the 2018 events is likely to continue for several years. Our assessment indicates that many common temperate European forest tree species are more vulnerable to extreme summer drought and heat waves than previously thought. As drought and heat events are likely to occur more frequently with the progression of climate change, temperate European forests might approach the point for a substantial ecological and economic transition. Our assessment also highlights the urgent need for a pan-European ground-based monitoring network suited to track individual tree mortality, supported by remote sensing products with high spatial and temporal resolution to track, analyse and forecast these transitions. more...
18. Stable Isotope Labelling Reveals Water and Carbon Fluxes in Temperate Tree Saplings Before Budbreak.
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Walde MG, Lehmann MM, Gessler A, Vitasse Y, and Diao H
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- Seasons, Soil chemistry, Deuterium metabolism, Deuterium analysis, Plant Stems metabolism, Carbon Isotopes analysis, Carbon Cycle, Water metabolism, Trees metabolism, Trees growth & development, Isotope Labeling, Carbon metabolism
- Abstract
Despite considerable experimental effort, the physiological mechanisms governing temperate tree species' water and carbon dynamics before the onset of the growing period remain poorly understood. We applied
2 H-enriched water during winter dormancy to the soil of four potted European tree species. After 8 weeks of chilling, hydrogen isotopes in stem, twig and bud water were measured six times during 2 consecutive weeks of forcing conditions (Experiment 1). Additionally, we pulse-labelled above-ground plant tissues using2 H-enriched water vapour and13 C-enriched CO2 7 days after exposure to forcing conditions to trace atmospheric water and carbon uptake (Experiment 2). Experiment 1 revealed soil water incorporation into the above-ground organs of all species during the chilling phase and significant species-specific differences in water allocation during the forcing conditions, which we attributed to differences in structural traits. Experiment 2 illustrated water vapour incorporation into all above-ground tissue of all species. However, the incorporation of carbon was found for evergreen saplings only. Our results suggest that temperate trees take up and reallocate soil water and absorb atmospheric water to maintain sufficient above-ground tissue hydration during winter. Therefore, our findings provide new insights into the water allocation dynamics of temperate trees during early spring., (© 2024 The Author(s). Plant, Cell & Environment published by John Wiley & Sons Ltd.) more...- Published
- 2025
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19. Stable water isotopes reveal the onset of bud dormancy in temperate trees, whereas water content is a better proxy for dormancy release.
- Author
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Walde MG, Wenden B, Chuine I, Gessler A, Saurer M, and Vitasse Y
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- Forests, Seasons, Species Specificity, Temperature, Trees physiology, Climate
- Abstract
Earlier spring growth onset in temperate forests is a visible effect of global warming that alters global water and carbon cycling. Consequently, it becomes crucial to accurately predict the future spring phenological shifts in vegetation under different climate warming scenarios. However, current phenological models suffer from a lack of physiological insights of tree dormancy and are rarely experimentally validated. Here, we sampled twig cuttings of five deciduous tree species at two climatically different locations (270 and 750 m a.s.l., ~ 2.3 °C difference) throughout the winter of 2019-20. Twig budburst success, thermal time to budburst, bud water content and short-term 2H-labelled water uptake into buds were quantified to link bud dormancy status with vascular water transport efficacy, with the objective of establishing connections between the dormancy status of buds and their effectiveness in vascular water transport. We found large differences in the dormancy status between species throughout the entire investigation period, likely reflecting species-specific environmental requirements to initiate and release dormancy, whereas only small differences in the dormancy status were found between the two studied sites. We found strong 2H-labelled water uptake into buds during leaf senescence, followed by a sharp decrease, which we ascribed to the initiation of endodormancy. However, surprisingly, we did not find a progressive increase in 2H-labelled water uptake into buds as winter advanced. Nonetheless, all examined tree species exhibited a consistent relationship between bud water content and dormancy status. Our results suggest that short-term 2H-labelled water uptake may not be a robust indicator of dormancy release, yet it holds promise as a method for tracking the induction of dormancy in deciduous trees. By contrast, bud water content emerges as a cost-effective and more reliable indicator of dormancy release., (© The Author(s) 2024. Published by Oxford University Press.) more...
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- 2024
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20. Feasting on the ordinary or starving for the exceptional in a warming climate: Phenological synchrony between spongy moth ( Lymantria dispar ) and budburst of six European tree species.
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Vitasse Y, Pohl N, Walde MG, Nadel H, Gossner MM, and Baumgarten F
- Abstract
Global warming is affecting the phenological cycles of plants and animals, altering the complex synchronization that has co-evolved over thousands of years between interacting species and trophic levels. Here, we examined how warmer winter conditions affect the timing of budburst in six common European trees and the hatching of a generalist leaf-feeding insect, the spongy moth Lymantria dispar , whose fitness depends on the synchrony between egg hatch and leaf emergence of the host tree. We applied four different temperature treatments to L. dispar eggs and twig cuttings, that mimicked warmer winters and reduced chilling temperatures that are necessary for insect diapause and bud dormancy release, using heated open-top chambers (ambient or +3.5°C), and heated greenhouses (maintained at >6°C or >10°C). In addition, we conducted preference and performance tests to determine which tree species the larvae prefer and benefit from the most. Budburst success and twig survival were highest for all tree species at ambient temperature conditions, whereas it declined under elevated winter temperature for Tilia cordata and Acer pseudoplatanus , likely due to a lack of chilling. While L. dispar egg hatch coincided with budburst in most tree species within 10 days under ambient conditions, it coincided with budburst only in Quercus robur , Carpinus betulus , and, to a lesser extent, Ulmus glabra under warmer conditions. With further warming, we, therefore, expect an increasing mismatch in trees with high chilling requirements, such as Fagus sylvatica and A. pseudoplatanus , but still good synchronization with trees having low chilling requirements, such as Q. robur and C. betulus . Surprisingly, first instar larvae preferred and gained weight faster when fed with leaves of F. sylvatica , while Q. robur ranked second. Our results suggest that spongy moth outbreaks are likely to persist in oak and hornbeam forests in western and central Europe., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.) more...
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- 2024
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21. Chronic warming and dry soils limit carbon uptake and growth despite a longer growing season in beech and oak.
- Author
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Didion-Gency M, Vitasse Y, Buchmann N, Gessler A, Gisler J, Schaub M, and Grossiord C
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- Seasons, Soil chemistry, Carbon, Trees, Fagus physiology, Quercus physiology
- Abstract
Progressively warmer and drier climatic conditions impact tree phenology and carbon cycling with large consequences for forest carbon balance. However, it remains unclear how individual impacts of warming and drier soils differ from their combined effects and how species interactions modulate tree responses. Using mesocosms, we assessed the multiyear impact of continuous air warming and lower soil moisture alone or in combination on phenology, leaf-level photosynthesis, nonstructural carbohydrate concentrations, and aboveground growth of young European beech (Fagus sylvatica L.) and Downy oak (Quercus pubescens Willd.) trees. We further tested how species interactions (in monocultures and in mixtures) modulated these effects. Warming prolonged the growing season of both species but reduced growth in oak. In contrast, lower moisture did not impact phenology but reduced carbon assimilation and growth in both species. Combined impacts of warming and drier soils did not differ from their single effects. Under warmer and drier conditions, performances of both species were enhanced in mixtures compared to monocultures. Our work revealed that higher temperature and lower soil moisture have contrasting impacts on phenology vs. leaf-level assimilation and growth, with the former being driven by temperature and the latter by moisture. Furthermore, we showed a compensation in the negative impacts of chronic heat and drought by tree species interactions., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of American Society of Plant Biologists.) more...
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- 2024
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22. Effect of climate warming on the timing of autumn leaf senescence reverses after the summer solstice.
- Author
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Zohner CM, Mirzagholi L, Renner SS, Mo L, Rebindaine D, Bucher R, Palouš D, Vitasse Y, Fu YH, Stocker BD, and Crowther TW
- Subjects
- Ecosystem, Forests, Seasons, Temperature, Climate Change, Plant Leaves, Plant Senescence
- Abstract
Climate change is shifting the growing seasons of plants, affecting species performance and biogeochemical cycles. Yet how the timing of autumn leaf senescence in Northern Hemisphere forests will change remains uncertain. Using satellite, ground, carbon flux, and experimental data, we show that early-season and late-season warming have opposite effects on leaf senescence, with a reversal occurring after the year's longest day (the summer solstice). Across 84% of the northern forest area, increased temperature and vegetation activity before the solstice led to an earlier senescence onset of, on average, 1.9 ± 0.1 days per °C, whereas warmer post-solstice temperatures extended senescence duration by 2.6 ± 0.1 days per °C. The current trajectories toward an earlier onset and slowed progression of senescence affect Northern Hemisphere-wide trends in growing-season length and forest productivity. more...
- Published
- 2023
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23. Networking the forest infrastructure towards near real-time monitoring - A white paper.
- Author
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Zweifel R, Pappas C, Peters RL, Babst F, Balanzategui D, Basler D, Bastos A, Beloiu M, Buchmann N, Bose AK, Braun S, Damm A, D'Odorico P, Eitel JUH, Etzold S, Fonti P, Rouholahnejad Freund E, Gessler A, Haeni M, Hoch G, Kahmen A, Körner C, Krejza J, Krumm F, Leuchner M, Leuschner C, Lukovic M, Martínez-Vilalta J, Matula R, Meesenburg H, Meir P, Plichta R, Poyatos R, Rohner B, Ruehr N, Salomón RL, Scharnweber T, Schaub M, Steger DN, Steppe K, Still C, Stojanović M, Trotsiuk V, Vitasse Y, von Arx G, Wilmking M, Zahnd C, and Sterck F more...
- Abstract
Forests account for nearly 90 % of the world's terrestrial biomass in the form of carbon and they support 80 % of the global biodiversity. To understand the underlying forest dynamics, we need a long-term but also relatively high-frequency, networked monitoring system, as traditionally used in meteorology or hydrology. While there are numerous existing forest monitoring sites, particularly in temperate regions, the resulting data streams are rarely connected and do not provide information promptly, which hampers real-time assessments of forest responses to extreme climate events. The technology to build a better global forest monitoring network now exists. This white paper addresses the key structural components needed to achieve a novel meta-network. We propose to complement - rather than replace or unify - the existing heterogeneous infrastructure with standardized, quality-assured linking methods and interacting data processing centers to create an integrated forest monitoring network. These automated (research topic-dependent) linking methods in atmosphere, biosphere, and pedosphere play a key role in scaling site-specific results and processing them in a timely manner. To ensure broad participation from existing monitoring sites and to establish new sites, these linking methods must be as informative, reliable, affordable, and maintainable as possible, and should be supplemented by near real-time remote sensing data. The proposed novel meta-network will enable the detection of emergent patterns that would not be visible from isolated analyses of individual sites. In addition, the near real-time availability of data will facilitate predictions of current forest conditions (nowcasts), which are urgently needed for research and decision making in the face of rapid climate change. We call for international and interdisciplinary efforts in this direction., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Zweifel Roman reports financial support was provided by Federal Office for the Environment., (Copyright © 2023 Elsevier B.V. All rights reserved.) more...
- Published
- 2023
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24. Global warming is increasing the discrepancy between green (actual) and thermal (potential) seasons of temperate trees.
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Fu YH, Geng X, Chen S, Wu H, Hao F, Zhang X, Wu Z, Zhang J, Tang J, Vitasse Y, Zohner CM, Janssens I, Stenseth NC, and Peñuelas J
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- Seasons, Climate, Temperature, Plant Leaves, Climate Change, Trees, Global Warming
- Abstract
Over the past decades, global warming has led to a lengthening of the time window during which temperatures remain favorable for carbon assimilation and tree growth, resulting in a lengthening of the green season. The extent to which forest green seasons have tracked the lengthening of this favorable period under climate warming, however, has not been quantified to date. Here, we used remote sensing data and long-term ground observations of leaf-out and coloration for six dominant species of European trees at 1773 sites, for a total of 6060 species-site combinations, during 1980-2016 and found that actual green season extensions (GS: 3.1 ± 0.1 day decade
-1 ) lag four times behind extensions of the potential thermal season (TS: 12.6 ± 0.1 day decade-1 ). Similar but less pronounced differences were obtained using satellite-derived vegetation phenology observations, that is, a lengthening of 4.4 ± 0.13 and 7.5 ± 0.13 day decade-1 for GS and TS, respectively. This difference was mainly driven by the larger advance in the onset of the thermal season compared to the actual advance of leaf-out dates (spring mismatch: 7.2 ± 0.1 day decade-1 ), but to a less extent caused by a phenological mismatch between GS and TS in autumn (2.4 ± 0.1 day decade-1 ). Our results showed that forest trees do not linearly track the new thermal window extension, indicating more complex interactions between winter and spring temperatures and photoperiod and a justification of demonstrating that using more sophisticated models that include the influence of chilling and photoperiod is needed to accurately predict spring phenological changes under warmer climate. They urge caution if such mechanisms are omitted to predict, for example, how vegetative health and growth, species distribution and crop yields will change in the future., (© 2022 John Wiley & Sons Ltd.) more...- Published
- 2023
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25. Linking human impacts to community processes in terrestrial and freshwater ecosystems.
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McFadden IR, Sendek A, Brosse M, Bach PM, Baity-Jesi M, Bolliger J, Bollmann K, Brockerhoff EG, Donati G, Gebert F, Ghosh S, Ho HC, Khaliq I, Lever JJ, Logar I, Moor H, Odermatt D, Pellissier L, de Queiroz LJ, Rixen C, Schuwirth N, Shipley JR, Twining CW, Vitasse Y, Vorburger C, Wong MKL, Zimmermann NE, Seehausen O, Gossner MM, Matthews B, Graham CH, Altermatt F, and Narwani A more...
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- Humans, Biodiversity, Fresh Water, Biological Evolution, Climate Change, Ecosystem, Anthropogenic Effects
- Abstract
Human impacts such as habitat loss, climate change and biological invasions are radically altering biodiversity, with greater effects projected into the future. Evidence suggests human impacts may differ substantially between terrestrial and freshwater ecosystems, but the reasons for these differences are poorly understood. We propose an integrative approach to explain these differences by linking impacts to four fundamental processes that structure communities: dispersal, speciation, species-level selection and ecological drift. Our goal is to provide process-based insights into why human impacts, and responses to impacts, may differ across ecosystem types using a mechanistic, eco-evolutionary comparative framework. To enable these insights, we review and synthesise (i) how the four processes influence diversity and dynamics in terrestrial versus freshwater communities, specifically whether the relative importance of each process differs among ecosystems, and (ii) the pathways by which human impacts can produce divergent responses across ecosystems, due to differences in the strength of processes among ecosystems we identify. Finally, we highlight research gaps and next steps, and discuss how this approach can provide new insights for conservation. By focusing on the processes that shape diversity in communities, we aim to mechanistically link human impacts to ongoing and future changes in ecosystems., (© 2022 The Authors. Ecology Letters published by John Wiley & Sons Ltd.) more...
- Published
- 2023
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26. Editorial: Plant phenology shifts and their ecological and climatic consequences.
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Fu YH, Prevéy JS, and Vitasse Y
- Abstract
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
- Published
- 2022
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27. Number of growth days and not length of the growth period determines radial stem growth of temperate trees.
- Author
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Etzold S, Sterck F, Bose AK, Braun S, Buchmann N, Eugster W, Gessler A, Kahmen A, Peters RL, Vitasse Y, Walthert L, Ziemińska K, and Zweifel R
- Subjects
- Humans, Seasons, Species Specificity, Climate Change, Soil
- Abstract
Radial stem growth dynamics at seasonal resolution are essential to understand how forests respond to climate change. We studied daily radial growth of 160 individuals of seven temperate tree species at 47 sites across Switzerland over 8 years. Growth of all species peaked in the early part of the growth season and commenced shortly before the summer solstice, but with species-specific seasonal patterns. Day length set a window of opportunity for radial growth. Within this window, the probability of daily growth was constrained particularly by air and soil moisture, resulting in intermittent growth to occur only on 29 to 77 days (30% to 80%) within the growth period. The number of days with growth largely determined annual growth, whereas the growth period length contributed less. We call for accounting for these non-linear intra-annual and species-specific growth dynamics in tree and forest models to reduce uncertainties in predictions under climate change., (© 2021 The Authors. Ecology Letters published by John Wiley & Sons Ltd.) more...
- Published
- 2022
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28. Impact of microclimatic conditions and resource availability on spring and autumn phenology of temperate tree seedlings.
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Vitasse Y, Baumgarten F, Zohner CM, Kaewthongrach R, Fu YH, Walde MG, and Moser B
- Subjects
- Climate Change, Plant Leaves, Seasons, Seedlings, Temperature, Fagus, Trees
- Abstract
Microclimatic effects (light, temperature) are often neglected in phenological studies and little information is known about the impact of resource availability (nutrient and water) on tree's phenological cycles. Here we experimentally studied spring and autumn phenology in four temperate trees in response to changes in bud albedo (white-painted vs black-painted buds), light conditions (nonshaded vs c. 70% shaded), water availability (irrigated, control and reduced precipitation) and nutrients (low vs high availability). We found that higher bud albedo or shade delayed budburst (up to +12 d), indicating that temperature is sensed locally within each bud. Leaf senescence was delayed by high nutrient availability (up to +7 d) and shade conditions (up to +39 d) in all species, except oak. Autumn phenological responses to summer droughts depended on species, with a delay for cherry (+7 d) and an advance for beech (-7 d). The strong phenological effects of bud albedo and light exposure reveal an important role of microclimatic variation on phenology. In addition to the temperature and photoperiod effects, our results suggest a tight interplay between source and sink processes in regulating the end of the seasonal vegetation cycle, which can be largely influenced by resource availability (light, water and nutrients)., (© 2021 The Authors. New Phytologist © 2021 New Phytologist Foundation.) more...
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- 2021
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29. Phenological and elevational shifts of plants, animals and fungi under climate change in the European Alps.
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Vitasse Y, Ursenbacher S, Klein G, Bohnenstengel T, Chittaro Y, Delestrade A, Monnerat C, Rebetez M, Rixen C, Strebel N, Schmidt BR, Wipf S, Wohlgemuth T, Yoccoz NG, and Lenoir J
- Subjects
- Animals, Climate Change, Ecosystem, Fungi, Plants, Seasons, Temperature, Butterflies, Odonata
- Abstract
Mountain areas are biodiversity hotspots and provide a multitude of ecosystem services of irreplaceable socio-economic value. In the European Alps, air temperature has increased at a rate of about 0.36°C decade
-1 since 1970, leading to glacier retreat and significant snowpack reduction. Due to these rapid environmental changes, this mountainous region is undergoing marked changes in spring phenology and elevational distribution of animals, plants and fungi. Long-term monitoring in the European Alps offers an excellent natural laboratory to synthetize climate-related changes in spring phenology and elevational distribution for a large array of taxonomic groups. This review assesses the climatic changes that have occurred across the European Alps during recent decades, spring phenological changes and upslope shifts of plants, animals and fungi from evidence in published papers and previously unpublished data. Our review provides evidence that spring phenology has been shifting earlier during the past four decades and distribution ranges show an upwards trend for most of the taxonomic groups for which there are sufficient data. The first observed activity of reptiles and terrestrial insects (e.g. butterflies) in spring has shifted significantly earlier, at an average rate of -5.7 and -6.0 days decade-1 , respectively. By contrast, the first observed spring activity of semi-aquatic insects (e.g. dragonflies and damselflies) and amphibians, as well as the singing activity or laying dates of resident birds, show smaller non-significant trends ranging from -1.0 to +1.3 days decade-1 . Leaf-out and flowering of woody and herbaceous plants showed intermediate trends with mean values of -2.4 and -2.8 days decade-1 , respectively. Regarding species distribution, plants, animals and fungi (N = 2133 species) shifted the elevation of maximum abundance (optimum elevation) upslope at a similar pace (on average between +18 and +25 m decade-1 ) but with substantial differences among taxa. For example, the optimum elevation shifted upward by +36.2 m decade-1 for terrestrial insects and +32.7 m decade-1 for woody plants, whereas it was estimated to range between -1.0 and +11 m decade-1 for semi-aquatic insects, ferns, birds and wood-decaying fungi. The upper range limit (leading edge) of most species also shifted upslope with a rate clearly higher for animals (from +47 to +91 m decade-1 ) than for plants (from +17 to +40 m decade-1 ), except for semi-aquatic insects (-4.7 m decade-1 ). Although regional land-use changes could partly explain some trends, the consistent upward shift found in almost all taxa all over the Alps is likely reflecting the strong warming and the receding of snow cover that has taken place across the European Alps over recent decades. However, with the possible exception of terrestrial insects, the upward shift of organisms seems currently too slow to track the pace of isotherm shifts induced by climate warming, estimated at about +62 to +71 m decade-1 since 1970. In the light of these results, species interactions are likely to change over multiple trophic levels through phenological and spatial mismatches. This nascent research field deserves greater attention to allow us to anticipate structural and functional changes better at the ecosystem level., (© 2021 Cambridge Philosophical Society.) more...- Published
- 2021
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30. Post-glacial re-colonization and natural selection have shaped growth responses of silver fir across Europe.
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Martínez-Sancho E, Rellstab C, Guillaume F, Bigler C, Fonti P, Wohlgemuth T, and Vitasse Y
- Subjects
- Droughts, Europe, Selection, Genetic, Switzerland, Climate Change, Ecosystem
- Abstract
Warmer climate and more frequent extreme droughts will pose major threats to forest ecosystems. Past demography processes due to post-glacial recolonization and adaptation to local environmental conditions are among the main contributors to genetic differentiation processes among provenances. Assessing the intra-specific variability of tree growth responses to such changes is crucial to explore a species' potential to cope with climate warming. We combined growth-related traits derived from tree-ring width series with neutral genetic information of 18 European provenances of silver fir (Abies alba Mill.) growing in two common garden experiments in Switzerland. Analyses based on neutral single nucleotide polymorphisms revealed that the studied provenances grouped into three longitudinal clusters. These three genetic clusters showed differences in growth traits (height and DBH), with the provenances from the eastern cluster exhibiting the highest growth. The Pyrenees cluster showed significantly lower recovery and resilience to the extreme drought of 2003 as well as lower values of growth autocorrelation. Q
ST -FST and correlation analyses with climate of provenance origin suggest that the differences among provenances found in some traits result from natural selection. Our study suggests that the last post-glacial re-colonization and natural selection are the major drivers explaining the intra-specific variability in growth of silver fir across Europe. These findings highlight the importance of combining dendroecology and genetic analyses on fitness-related traits to assess the potential of a species to cope with global environmental change and provide insights to support assisted gene flow to ensure the persistence of the species in European forests., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.) more...- Published
- 2021
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31. Chilled to be forced: the best dose to wake up buds from winter dormancy.
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Baumgarten F, Zohner CM, Gessler A, and Vitasse Y
- Subjects
- Climate, Plant Leaves, Seasons, Temperature, Climate Change, Trees
- Abstract
Over the last decades, spring leaf-out of temperate and boreal trees has substantially advanced in response to global warming, affecting terrestrial biogeochemical fluxes and the Earth's climate system. However, it remains unclear whether leaf-out will continue to advance with further warming because species' effective chilling temperatures, as well as the amount of chilling time required to break dormancy, are still largely unknown for most forest tree species. Here, we assessed the progress of winter dormancy and quantified the efficiency of different chilling temperatures in six dominant temperate European tree species by exposing 1170 twig cuttings to a range of temperatures from -2°C to 10°C for 1, 3, 6 or 12 wk. We found that freezing temperatures were most effective for half of the species or as effective as chilling temperatures up to 10°C, that is, leading to minimum thermal time to and maximum success of budburst. Interestingly, chilling duration had a much larger effect on dormancy release than absolute chilling temperature. Our experimental results challenge the common assumption that optimal chilling temperatures range c. 4-6°C, instead revealing strong sensitivity to a large range of temperatures. These findings are valuable for improving phenological models and predicting future spring phenology in a warming world., (© 2021 The Authors New Phytologist © 2021 New Phytologist Foundation.) more...
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- 2021
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32. Editorial: Experimental Manipulations to Predict Future Plant Phenology.
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Prevéy JS, Vitasse Y, and Fu Y
- Abstract
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
- Published
- 2021
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33. Assessing the Effectiveness of in-situ Active Warming Combined With Open Top Chambers to Study Plant Responses to Climate Change.
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Frei ER, Schnell L, Vitasse Y, Wohlgemuth T, and Moser B
- Abstract
Temperature manipulation experiments are an effective way for testing plant responses to future climate conditions, especially for predicting shifts in plant phenological events. While passive warming techniques are widely used to elevate temperature in low stature plant communities, active warming has been applied less frequently due to the associated resource requirements. In forest ecosystems, however, active warming is crucial to simulate projected air temperature rises of 3-5 K, especially at the warm (i.e., southern and low elevation) range edges of tree species. Moreover, the warming treatment should be applied to the complete height of the experimental plants, e.g., regenerating trees in the understory. Here, we combined open top chambers (OTCs) with active heat sources, an electric heater (OTC-EH) and warming cables (OTC-WC), and tested the effectiveness of these set-ups to maintain constant temperature differences compared to ambient temperature across 18 m
2 plots. This chamber size is needed to grow tree saplings in mixture in forest gaps for 3 to 10 years. With passive warming only, an average temperature increase of approx. 0.4 K as compared to ambient conditions was achieved depending on time of the day and weather conditions. In the actively warmed chambers, average warming exceeded ambient temperatures by 2.5 to 2.8 K and was less variable over time. However, active warming also reduced air humidity by about 15%. These results underline the need to complement passive warming with active warming in order to achieve constant temperature differences appropriate for climate change simulations under all weather conditions in large OTCs. Since we observed considerable horizontal and vertical temperature variation within OTCs with temperature differences of up to 16.9 K, it is essential to measure and report within-plot temperature distribution as well as temporal temperature variation. If temperature distributions within large OTCs are well characterized, they may be incorporated in the experimental design helping to identify non-linear or threshold responses to warming., (Copyright © 2020 Frei, Schnell, Vitasse, Wohlgemuth and Moser.) more...- Published
- 2020
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34. Climate warming increases spring phenological differences among temperate trees.
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Geng X, Fu YH, Hao F, Zhou X, Zhang X, Yin G, Vitasse Y, Piao S, Niu K, De Boeck HJ, Menzel A, and Peñuelas J
- Subjects
- Climate Change, Europe, Plant Leaves, Seasons, Temperature, Ecosystem, Trees
- Abstract
Climate warming has substantially advanced spring leaf flushing, but winter chilling and photoperiod co-determine the leaf flushing process in ways that vary among species. As a result, the interspecific differences in spring phenology (IDSP) are expected to change with climate warming, which may, in turn, induce negative or positive ecological consequences. However, the temporal change of IDSP at large spatiotemporal scales remains unclear. In this study, we analyzed long-term in-situ observations (1951-2016) of six, coexisting temperate tree species from 305 sites across Central Europe and found that phenological ranking did not change when comparing the rapidly warming period 1984-2016 to the marginally warming period 1951-1983. However, the advance of leaf flushing was significantly larger in early-flushing species EFS (6.7 ± 0.3 days) than in late-flushing species LFS (5.9 ± 0.2 days) between the two periods, indicating extended IDSP. This IDSP extension could not be explained by differences in temperature sensitivity between EFS and LFS; however, climatic warming-induced heat accumulation effects on leaf flushing, which were linked to a greater heat requirement and higher photoperiod sensitivity in LFS, drove the shifts in IDSP. Continued climate warming is expected to further extend IDSP across temperate trees, with associated implications for ecosystem function., (© 2020 John Wiley & Sons Ltd.) more...
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- 2020
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35. Late-spring frost risk between 1959 and 2017 decreased in North America but increased in Europe and Asia.
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Zohner CM, Mo L, Renner SS, Svenning JC, Vitasse Y, Benito BM, Ordonez A, Baumgarten F, Bastin JF, Sebald V, Reich PB, Liang J, Nabuurs GJ, de-Miguel S, Alberti G, Antón-Fernández C, Balazy R, Brändli UB, Chen HYH, Chisholm C, Cienciala E, Dayanandan S, Fayle TM, Frizzera L, Gianelle D, Jagodzinski AM, Jaroszewicz B, Jucker T, Kepfer-Rojas S, Khan ML, Kim HS, Korjus H, Johannsen VK, Laarmann D, Lang M, Zawila-Niedzwiecki T, Niklaus PA, Paquette A, Pretzsch H, Saikia P, Schall P, Šebeň V, Svoboda M, Tikhonova E, Viana H, Zhang C, Zhao X, and Crowther TW more...
- Subjects
- Asia, Europe, Forests, North America, Phenotype, Spatio-Temporal Analysis, Temperature, Climate Change, Cold Temperature, Plant Leaves growth & development, Seasons, Trees growth & development
- Abstract
Late-spring frosts (LSFs) affect the performance of plants and animals across the world's temperate and boreal zones, but despite their ecological and economic impact on agriculture and forestry, the geographic distribution and evolutionary impact of these frost events are poorly understood. Here, we analyze LSFs between 1959 and 2017 and the resistance strategies of Northern Hemisphere woody species to infer trees' adaptations for minimizing frost damage to their leaves and to forecast forest vulnerability under the ongoing changes in frost frequencies. Trait values on leaf-out and leaf-freezing resistance come from up to 1,500 temperate and boreal woody species cultivated in common gardens. We find that areas in which LSFs are common, such as eastern North America, harbor tree species with cautious (late-leafing) leaf-out strategies. Areas in which LSFs used to be unlikely, such as broad-leaved forests and shrublands in Europe and Asia, instead harbor opportunistic tree species (quickly reacting to warming air temperatures). LSFs in the latter regions are currently increasing, and given species' innate resistance strategies, we estimate that ∼35% of the European and ∼26% of the Asian temperate forest area, but only ∼10% of the North American, will experience increasing late-frost damage in the future. Our findings reveal region-specific changes in the spring-frost risk that can inform decision-making in land management, forestry, agriculture, and insurance policy., Competing Interests: The authors declare no competing interest. more...
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- 2020
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36. Shifts in the temperature-sensitive periods for spring phenology in European beech and pedunculate oak clones across latitudes and over recent decades.
- Author
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Wenden B, Mariadassou M, Chmielewski FM, and Vitasse Y
- Subjects
- Climate Change, Norway, Portugal, Seasons, Temperature, Trees, Fagus, Quercus
- Abstract
Spring phenology of temperate trees has advanced worldwide in response to global warming. However, increasing temperatures may not necessarily lead to further phenological advance, especially in the warmer latitudes because of insufficient chilling and/or shorter day length. Determining the start of the forcing phase, that is, when buds are able to respond to warmer temperatures in spring, is therefore crucial to predict how phenology will change in the future. In this study, we used 4,056 leaf-out date observations during the period 1969-2017 for clones of European beech (Fagus sylvatica L.) and pedunculate oak (Quercus robur L.) planted in 63 sites covering a large latitudinal gradient (from Portugal ~41°N to Norway ~63°N) at the International Phenological Gardens in order to (a) evaluate how the sensitivity periods to forcing and chilling have changed with climate warming, and (b) test whether consistent patterns occur along biogeographical gradients, that is, from colder to warmer environments. Partial least squares regressions suggest that the length of the forcing period has been extended over the recent decades with climate warming in the colder latitudes but has been shortened in the warmer latitudes for both species, with a more pronounced shift for beech. We attribute the lengthening of the forcing period in the colder latitudes to earlier opportunities with temperatures that can promote bud development. In contrast, at warmer or oceanic climates, the beginning of the forcing period has been delayed, possibly due to insufficient chilling. However, in spite of a later beginning of the forcing period, spring phenology has continued to advance at these areas due to a faster satisfaction of heat requirements induced by climate warming. Overall, our results support that ongoing climate warming will have different effects on the spring phenology of forest trees across latitudes due to the interactions between chilling, forcing and photoperiod., (© 2019 John Wiley & Sons Ltd.) more...
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- 2020
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37. Rising air humidity during spring does not trigger leaf-out in temperate woody plants.
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Zohner CM, Strauß AFT, Baumgarten F, Vitasse Y, and Renner SS
- Subjects
- Air, Climate Change, Seasons, Humidity, Plant Leaves physiology, Temperature, Trees physiology
- Published
- 2020
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38. Shortened temperature-relevant period of spring leaf-out in temperate-zone trees.
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Fu YH, Geng X, Hao F, Vitasse Y, Zohner CM, Zhang X, Zhou X, Yin G, Peñuelas J, Piao S, and Janssens IA
- Subjects
- Europe, Seasons, Temperature, Plant Leaves, Trees
- Abstract
Temperature during a particular period prior to spring leaf-out, the temperature-relevant period (TRP), is a strong determinant of the leaf-out date in temperate-zone trees. Climatic warming has substantially advanced leaf-out dates in temperate biomes worldwide, but its effect on the beginning and length of the TRP has not yet been explored, despite its direct relevance for phenology modeling. Using 1,551 species-site combinations of long-term (1951-2016) in situ observations on six tree species (namely, Aesculus hippocastanum, Alnus glutinosa, Betula pendula, Fagus sylvatica, Fraxinus excelsior, and Quercus robur) in central Europe, we found that the advancing leaf-out was accompanied by a shortening of the TRP. On average across all species and sites, the length of the TRP significantly decreased by 23% (p < .05), from 60 ± 4 days during 1951-1965 to 47 ± 4 days during 2002-2016. Importantly, the average start date of the TRP did not vary significantly over the study period (March 2-5, DOY = 61-64), which could be explained by sufficient chilling over the study period in the regions considered. The advanced leaf-out date with unchanged beginning of the TRP can be explained by the faster accumulation of the required heat due to climatic warming, which overcompensated for the retarding effect of shortening daylength on bud development. This study shows that climate warming has not yet affected the mean TRP starting date in the study region, implying that phenology modules in global land surface models might be reliable assuming a fixed TRP starting date at least for the temperate central Europe. Field warming experiments do, however, remain necessary to test to what extent the length of TRP will continue to shorten and whether the starting date will remain stable under future climate conditions., (© 2019 John Wiley & Sons Ltd.) more...
- Published
- 2019
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39. Contrasting resistance and resilience to extreme drought and late spring frost in five major European tree species.
- Author
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Vitasse Y, Bottero A, Cailleret M, Bigler C, Fonti P, Gessler A, Lévesque M, Rohner B, Weber P, Rigling A, and Wohlgemuth T
- Subjects
- Climate Change, Ecosystem, Forests, Trees, Droughts, Fagus
- Abstract
Extreme climate events (ECEs) such as severe droughts, heat waves, and late spring frosts are rare but exert a paramount role in shaping tree species distributions. The frequency of such ECEs is expected to increase with climate warming, threatening the sustainability of temperate forests. Here, we analyzed 2,844 tree-ring width series of five dominant European tree species from 104 Swiss sites ranging from 400 to 2,200 m a.s.l. for the period 1930-2016. We found that (a) the broadleaved oak and beech are sensitive to late frosts that strongly reduce current year growth; however, tree growth is highly resilient and fully recovers within 2 years; (b) radial growth of the conifers larch and spruce is strongly and enduringly reduced by spring droughts-these species are the least resistant and resilient to droughts; (c) oak, silver fir, and to a lower extent beech, show higher resistance and resilience to spring droughts and seem therefore better adapted to the future climate. Our results allow a robust comparison of the tree growth responses to drought and spring frost across large climatic gradients and provide striking evidence that the growth of some of the most abundant and economically important European tree species will be increasingly limited by climate warming. These results could serve for supporting species selection to maintain the sustainability of forest ecosystem services under the expected increase in ECEs., (© 2019 John Wiley & Sons Ltd.) more...
- Published
- 2019
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40. Daylength helps temperate deciduous trees to leaf-out at the optimal time.
- Author
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Fu YH, Zhang X, Piao S, Hao F, Geng X, Vitasse Y, Zohner C, Peñuelas J, and Janssens IA
- Subjects
- Climate, Forests, Seasons, Temperature, Plant Leaves, Trees
- Abstract
Global warming has led to substantially earlier spring leaf-out in temperate-zone deciduous trees. The interactive effects of temperature and daylength underlying this warming response remain unclear. However, they need to be accurately represented by earth system models to improve projections of the carbon and energy balances of temperate forests and the associated feedbacks to the Earth's climate system. We studied the control of leaf-out by daylength and temperature using data from six tree species across 2,377 European phenological network (www.pep725.eu), each with at least 30 years of observations. We found that, in addition to and independent of the known effect of chilling, daylength correlates negatively with the heat requirement for leaf-out in all studied species. In warm springs when leaf-out is early, days are short and the heat requirement is higher than in an average spring, which mitigates the warming-induced advancement of leaf-out and protects the tree against precocious leaf-out and the associated risks of late frosts. In contrast, longer-than-average daylength (in cold springs when leaf-out is late) reduces the heat requirement for leaf-out, ensuring that trees do not leaf-out too late and miss out on large amounts of solar energy. These results provide the first large-scale empirical evidence of a widespread daylength effect on the temperature sensitivity of leaf-out phenology in temperate deciduous trees., (© 2019 John Wiley & Sons Ltd.) more...
- Published
- 2019
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41. Short photoperiod reduces the temperature sensitivity of leaf-out in saplings of Fagus sylvatica but not in horse chestnut.
- Author
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Fu YH, Piao S, Zhou X, Geng X, Hao F, Vitasse Y, and Janssens IA
- Subjects
- Aesculus growth & development, Europe, Fagus growth & development, Forests, Global Warming, Seasons, Species Specificity, Aesculus physiology, Fagus physiology, Photoperiod, Plant Leaves growth & development, Temperature
- Abstract
Leaf phenology is one of the most reliable bioindicators of ongoing global warming in temperate and boreal zones because it is highly sensitive to temperature variation. A large number of studies have reported advanced spring leaf-out due to global warming, yet the temperature sensitivity of leaf-out has significantly decreased in temperate deciduous tree species over the past three decades. One of the possible mechanisms is that photoperiod is limiting further advance to protect the leaves against potential damaging frosts. However, the "photoperiod limitation" hypothesis remains poorly investigated and experimentally tested. Here, we conducted a photoperiod- and temperature-manipulation experiment in climate chambers on two common deciduous species in Europe: Fagus sylvatica (European beech, a typically late flushing species) and Aesculus hippocastanum (horse chestnut, a typically early flushing species). In agreement with previous studies, we found that the warming significantly advanced the leaf-out dates by 4.3 and 3.7 days/°C for beech and horse chestnut saplings, respectively. However, shorter photoperiod significantly reduced the temperature sensitivity of beech only (3.0 days/°C) by substantially increasing the heat requirement to avoid leafing-out too early. Interestingly, the photoperiod limitation only occurs below a certain daylength (photoperiod threshold) when the warming increased above 4°C for beech trees. In contrast, for chestnut, no photoperiod threshold was found even when the ambient air temperature was warmed by 5°C. Given the species-specific photoperiod effect on leaf phenology, the sequence of the leaf-out timing among forest tree species may change under future climate warming conditions. Nonphotoperiodic species may benefit from warmer springs by starting the growing season earlier than photoperiodic sensitive species, modifying forest ecosystem structure and functions, but this photoperiod limitation needs to be further investigated experimentally in numerous species., (© 2019 John Wiley & Sons Ltd.) more...
- Published
- 2019
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42. Daily Maximum Temperatures Induce Lagged Effects on Leaf Unfolding in Temperate Woody Species Across Large Elevational Gradients.
- Author
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Bigler C and Vitasse Y
- Abstract
The timing of leaf unfolding in temperate woody species is predominantly controlled by the seasonal course of temperature in late winter and early spring. However, quantifying lagged temperature effects on spring phenology is still challenging. Here, we aimed at investigating lagged and potentially non-linear effects of daily maximum temperatures on the probability of leaf unfolding in temperate woody species growing across large elevational gradients. We analyzed 5280 observations of leaf-out time of four tree species (European beech, horse chestnut, European larch, Norway spruce) and one shrub species (common hazel) that were recorded by volunteers over 40 years at 42 locations in Switzerland. We used a case-crossover sampling design to match leaf-out dates with control dates (i.e., dates before or after leaf-out), and analyzed these data with conditional logistic regression accounting for lagged temperature effects over 60 days. Multivariate meta-analyses were used to synthesize lagged temperature and elevational effects on leaf unfolding across multiple phenological stations. Temperature effects on the probability of leaf unfolding were largest at relatively short lags (i.e., within ca. 10 days) and decreased with increasing lags. Short- to mid-term effects (i.e., within ca. 10 to 20 days) were larger for late-leafing species known to be photoperiod-sensitive (beech, Norway spruce). Temperature effects increased for the broadleaved species (horse chestnut, hazel, beech) with decreasing elevation, particularly within ca. 10 to 40 days, i.e., leaf unfolding occurs more rapidly at low elevations for a given daily maximum temperature. Our novel findings provide evidence of cumulative and long-term temperature effects on leaf unfolding, whereby the efficiency of relatively high temperatures to trigger leaf-out becomes higher shortly before bud burst. These lagged associations between temperature and leaf unfolding improve our understanding of phenological responses across temperate woody species with differing ecological requirements that occur along elevational gradients. more...
- Published
- 2019
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43. Unchanged risk of frost exposure for subalpine and alpine plants after snowmelt in Switzerland despite climate warming.
- Author
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Klein G, Rebetez M, Rixen C, and Vitasse Y
- Subjects
- Risk, Seasons, Switzerland, Climate Change, Plants, Snow, Temperature
- Abstract
The length of the snow-free season is a key factor regulating plant phenology and shaping plant community composition in cold regions. While global warming has significantly advanced the time of snowmelt and the growth period at all elevations in the Swiss Alps, it remains unclear if it has altered the likelihood of frost risk for alpine plants. Here, we analyzed the influence of the snowmelt timing on the risk of frost exposure for subalpine and alpine plants shortly after snowmelt, i.e., during their most vulnerable period to frost at the beginning of their growth period. Furthermore, we tested whether recent climate warming has changed the risk of exposure of plants to frost after snowmelt. We analyzed snow and air temperature data in the Swiss Alps using six weather stations covering the period 1970-2016 and 77 weather stations covering the period 1998-2016, spanning elevations from 1418 to 2950 m asl. When analyzed across all years within each station, our results showed strong negative relationships between the time of snowmelt and the frequency and intensity of frost during the most vulnerable period to frost for subalpine and alpine plants, indicating a higher frost risk damage for plants during years with earlier snowmelt. However, over the last 46 years, the time of snowmelt and the last spring frost date have advanced at similar rates, so that the frequency and intensity of frost during the vulnerable period for plants remained unchanged. more...
- Published
- 2018
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44. Vapor-pressure deficit and extreme climatic variables limit tree growth.
- Author
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Sanginés de Cárcer P, Vitasse Y, Peñuelas J, Jassey VEJ, Buttler A, and Signarbieux C
- Subjects
- Europe, Fagus, Picea physiology, Seasons, Species Specificity, Temperature, Vapor Pressure, Climate Change, Forests, Trees growth & development
- Abstract
Assessing the effect of global warming on forest growth requires a better understanding of species-specific responses to climate change conditions. Norway spruce and European beech are among the dominant tree species in Europe and are largely used by the timber industry. Their sensitivity to changes in climate and extreme climatic events, however, endangers their future sustainability. Identifying the key climatic factors limiting their growth and survival is therefore crucial for assessing the responses of these two species to ongoing climate change. We studied the vulnerability of beech and spruce to warmer and drier conditions by transplanting saplings from the top to the bottom of an elevational gradient in the Jura Mountains in Switzerland. We (1) demonstrated that a longer growing season due to warming could not fully account for the positive growth responses, and the positive effect on sapling productivity was species-dependent, (2) demonstrated that the contrasting growth responses of beech and spruce were mainly due to different sensitivities to elevated vapor-pressure deficits (VPD), (3) determined the species-specific limits to VPD above which growth rate began to decline, and (4) demonstrated that models incorporating extreme climatic events could account for the response of growth to warming better than models using only average values. These results support that the sustainability of forest trees in the coming decades will depend on how extreme climatic events will change, irrespective of the overall warming trend., (© 2017 John Wiley & Sons Ltd.) more...
- Published
- 2018
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45. Global warming leads to more uniform spring phenology across elevations.
- Author
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Vitasse Y, Signarbieux C, and Fu YH
- Subjects
- Ecosystem, Forests, Models, Biological, Switzerland, Temperature, Altitude, Global Warming, Plant Leaves growth & development, Plant Leaves physiology, Seasons, Trees growth & development, Trees physiology
- Abstract
One hundred years ago, Andrew D. Hopkins estimated the progressive delay in tree leaf-out with increasing latitude, longitude, and elevation, referred to as "Hopkins' bioclimatic law." What if global warming is altering this well-known law? Here, based on ∼20,000 observations of the leaf-out date of four common temperate tree species located in 128 sites at various elevations in the European Alps, we found that the elevation-induced phenological shift (EPS) has significantly declined from 34 d⋅1,000 m
-1 conforming to Hopkins' bioclimatic law in 1960, to 22 d⋅1,000 m-1 in 2016, i.e., -35%. The stronger phenological advance at higher elevations, responsible for the reduction in EPS, is most likely to be connected to stronger warming during late spring as well as to warmer winter temperatures. Indeed, under similar spring temperatures, we found that the EPS was substantially reduced in years when the previous winter was warmer. Our results provide empirical evidence for a declining EPS over the last six decades. Future climate warming may further reduce the EPS with consequences for the structure and function of mountain forest ecosystems, in particular through changes in plant-animal interactions, but the actual impact of such ongoing change is today largely unknown., Competing Interests: The authors declare no conflict of interest. more...- Published
- 2018
- Full Text
- View/download PDF
46. Asymmetric effects of cooler and warmer winters on beech phenology last beyond spring.
- Author
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Signarbieux C, Toledano E, Sanginés de Carcer P, Fu YH, Schlaepfer R, Buttler A, and Vitasse Y
- Subjects
- Climate Change, Cold Temperature, Hot Temperature, Plant Development, Trees growth & development, Climate, Fagus physiology, Seasons, Trees physiology
- Abstract
In temperate trees, the timings of plant growth onset and cessation affect biogeochemical cycles, water, and energy balance. Currently, phenological studies largely focus on specific phenophases and on their responses to warming. How differently spring phenology responds to the warming and cooling, and affects the subsequent phases, has not been yet investigated in trees. Here, we exposed saplings of Fagus sylvatica L. to warmer and cooler climate during the winter 2013-2014 by conducting a reciprocal transplant experiment between two elevations (1,340 vs. 371 m a.s.l., ca. 6°C difference) in the Swiss Jura mountains. To test the legacy effects of earlier or later budburst on the budset timing, saplings were moved back to their original elevation shortly after the occurrence of budburst in spring 2014. One degree decrease in air temperature in winter/spring resulted in a delay of 10.9 days in budburst dates, whereas one degree of warming advanced the date by 8.8 days. Interestingly, we also found an asymmetric effect of the warmer winter vs. cooler winter on the budset timing in late summer. Budset of saplings that experienced a cooler winter was delayed by 31 days compared to the control, whereas it was delayed by only 10 days in saplings that experienced a warmer winter. Budburst timing in 2015 was not significantly impacted by the artificial advance or delay of the budburst timing in 2014, indicating that the legacy effects of the different phenophases might be reset during each winter. Adapting phenological models to the whole annual phenological cycle, and considering the different response to cooling and warming, would improve predictions of tree phenology under future climate warming conditions., (© 2017 John Wiley & Sons Ltd.) more...
- Published
- 2017
- Full Text
- View/download PDF
47. Frost hardening and dehardening potential in temperate trees from winter to budburst.
- Author
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Vitra A, Lenz A, and Vitasse Y
- Subjects
- Analysis of Variance, Plant Dormancy physiology, Species Specificity, Temperature, Time Factors, Freezing, Seasons, Trees physiology
- Abstract
We investigated how deciduous trees can adjust their freezing resistance in response to temperature during the progress of the ecodormancy phase, from midwinter to budburst. We regularly sampled twigs of four different temperate deciduous tree species from January to the leaf-out date. Using computer-controlled freezers and climate chambers, the freezing resistance of buds was measured directly after sampling and also after the application of artificial hardening and dehardening treatments, simulating cold and warm spells. The thermal time to budburst in forcing conditions (c. 20°C) was also quantified at each sampling as a proxy for dormancy depth. Earlier flushing species showed higher freezing resistance than late flushing species at either similar bud development stage or similar dormancy depth. Overall, freezing resistance and its hardening and dehardening potential dramatically decreased during the progress of ecodormancy and became almost nil during budburst. Our results suggest that extreme cold events in winter are not critical for trees, as freezing resistance can be largely enhanced during this period. By contrast, the timing of budburst is a critical component of tree fitness. Our results provide quantitative values of the freezing resistance dynamics during ecodormancy, particularly valuable in process-based species distribution models., (© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.) more...
- Published
- 2017
- Full Text
- View/download PDF
48. 'Hearing' alpine plants growing after snowmelt: ultrasonic snow sensors provide long-term series of alpine plant phenology.
- Author
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Vitasse Y, Rebetez M, Filippa G, Cremonese E, Klein G, and Rixen C
- Subjects
- Altitude, Soil, Switzerland, Temperature, Ultrasonics, Plant Development, Seasons, Snow
- Abstract
In alpine environments, the growing season is severely constrained by low temperature and snow. Here, we aim at determining the climatic factors that best explain the interannual variation in spring growth onset of alpine plants, and at examining whether photoperiod might limit their phenological response during exceptionally warm springs and early snowmelts. We analysed 17 years of data (1998-2014) from 35 automatic weather stations located in subalpine and alpine zones ranging from 1560 to 2450 m asl in the Swiss Alps. These stations are equipped with ultrasonic sensors for snow depth measurements that are also able to detect plant growth in spring and summer, giving a unique opportunity to analyse snow and climate effects on alpine plant phenology. Our analysis showed high phenological variation among years, with one exceptionally early and late spring, namely 2011 and 2013. Overall, the timing of snowmelt and the beginning of plant growth were tightly linked irrespective of the elevation of the station. Snowmelt date was the best predictor of plant growth onset with air temperature after snowmelt modulating the plants' development rate. This multiple series of alpine plant phenology suggests that currently alpine plants are directly tracking climate change with no major photoperiod limitation. more...
- Published
- 2017
- Full Text
- View/download PDF
49. Long-term linear trends mask phenological shifts.
- Author
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Fu YH, Piao S, Ciais P, Huang M, Menzel A, Peaucelle M, Peng S, Song Y, Vitasse Y, Zeng Z, Zhao H, Zhou G, Peñuelas J, and Janssens IA
- Subjects
- Seasons, Temperature, Climate Change statistics & numerical data, Plant Leaves growth & development
- Published
- 2016
- Full Text
- View/download PDF
50. Coordination between growth, phenology and carbon storage in three coexisting deciduous tree species in a temperate forest.
- Author
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Klein T, Vitasse Y, and Hoch G
- Subjects
- Betulaceae growth & development, Betulaceae metabolism, Carbon metabolism, Ecology, Fagus growth & development, Fagus metabolism, Meristem growth & development, Meristem metabolism, Photosynthesis, Plant Leaves growth & development, Plant Leaves metabolism, Plant Stems growth & development, Plant Stems metabolism, Quercus growth & development, Quercus metabolism, Starch metabolism, Trees growth & development, Trees metabolism, Trees physiology, Betulaceae physiology, Carbohydrate Metabolism, Fagus physiology, Forests, Meristem physiology, Quercus physiology, Seasons
- Abstract
In deciduous trees growing in temperate forests, bud break and growth in spring must rely on intrinsic carbon (C) reserves. Yet it is unclear whether growth and C storage occur simultaneously, and whether starch C in branches is sufficient for refoliation. To test in situ the relationships between growth, phenology and C utilization, we monitored stem growth, leaf phenology and stem and branch nonstructural carbohydrate (NSC) dynamics in three deciduous species: Carpinus betulus L., Fagus sylvatica L. and Quercus petraea (Matt.) Liebl. To quantify the role of NSC in C investment into growth, a C balance approach was applied. Across the three species, >95% of branchlet starch was consumed during bud break, confirming the importance of C reserves for refoliation in spring. The C balance calculation showed that 90% of the C investment in foliage (7.0-10.5 kg tree(-1) and 5-17 times the C needed for annual stem growth) was explained by simultaneous branchlet starch degradation. Carbon reserves were recovered sooner than expected, after leaf expansion, in parallel with stem growth. Carpinus had earlier leaf phenology (by ∼25 days) but delayed cambial growth (by ∼15 days) than Fagus and Quercus, the result of a competitive strategy to flush early, while having lower NSC levels., (© The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.) more...
- Published
- 2016
- Full Text
- View/download PDF
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