2020 - UMR Silva

[hal-02434220] TRY plant trait database – enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration , biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.

ano.nymous@ccsd.cnrs.fr.invalid (Jens Kattge) 09 Nov 2020

https://amu.hal.science/hal-02434220v1

[hal-02650649] Long-term thermal sensitivity of Earth’s tropical forests

The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (−9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth’s climate.

ano.nymous@ccsd.cnrs.fr.invalid (Martin J P Sullivan) 17 Aug 2024

https://hal.umontpellier.fr/hal-02650649v1

[hal-03778635] The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data

The FLUXNET2015 dataset provides ecosystem-scale data on CO 2 , water, and energy exchange between the biosphere and the atmosphere, and other meteorological and biological measurements, from 212 sites around the globe (over 1500 site-years, up to and including year 2014). These sites, independently managed and operated, voluntarily contributed their data to create global datasets. Data were quality controlled and processed using uniform methods, to improve consistency and intercomparability across sites. The dataset is already being used in a number of applications, including ecophysiology studies, remote sensing studies, and development of ecosystem and Earth system models. FLUXNET2015 includes derived-data products, such as gap-filled time series, ecosystem respiration and photosynthetic uptake estimates, estimation of uncertainties, and metadata about the measurements, presented for the first time in this paper. In addition, 206 of these sites are for the first time distributed under a Creative Commons (CC-BY 4.0) license. This paper details this enhanced dataset and the processing methods, now made available as open-source codes, making the dataset more accessible, transparent, and reproducible.

ano.nymous@ccsd.cnrs.fr.invalid (Gilberto Pastorello) 16 Sep 2022

https://hal.science/hal-03778635v1

[hal-02995533] Ecosystem transpiration and evaporation: Insights from three water flux partitioning methods across FLUXNET sites

We apply and compare three widely applicable methods for estimating ecosystem transpiration (T) from eddy covariance (EC) data across 251 FLUXNET sites globally. All three methods are based on the coupled water and carbon relationship, but they differ in assumptions and parameterizations. Intercomparison of the three daily T estimates shows high correlation among methods (R between .89 and .94), but a spread in magnitudes of T/ET (evapotranspiration) from 45% to 77%. When compared at six sites with concurrent EC and sap flow measurements, all three EC‐based T estimates show higher correlation to sap flow‐based T than EC‐based ET. The partitioning methods show expected tendencies of T/ET increasing with dryness (vapor pressure deficit and days since rain) and with leaf area index (LAI). Analysis of 140 sites with high‐quality estimates for at least two continuous years shows that T/ET variability was 1.6 times higher across sites than across years. Spatial variability of T/ET was primarily driven by vegetation and soil characteristics (e.g., crop or grass designation, minimum annual LAI, soil coarse fragment volume) rather than climatic variables such as mean/standard deviation of temperature or precipitation. Overall, T and T/ET patterns are plausible and qualitatively consistent among the different water flux partitioning methods implying a significant advance made for estimating and understanding T globally, while the magnitudes remain uncertain. Our results represent the first extensive EC data‐based estimates of ecosystem T permitting a data‐driven perspective on the role of plants’ water use for global water and carbon cycling in a changing climate.

ano.nymous@ccsd.cnrs.fr.invalid (Jacob Nelson) 07 Jun 2022

https://hal.univ-lorraine.fr/hal-02995533v1

[hal-02957456] Non-stomatal processes reduce gross primary productivity in temperate forest ecosystems during severe edaphic drought

Severe drought events are known to cause important reductions of gross primary productivity (GPP) in forest ecosystems. However, it is still unclear whether this reduction originates from stomatal closure (Stomatal Origin Limitation) and/or non-stomatal limitations (Non-SOL). In this study, we investigated the impact of edaphic drought in 2018 onGPPand its origin (SOL, NSOL) using a dataset of 10 European forest ecosystem flux towers. In all stations whereGPPreductions were observed during the drought, these were largely explained by declines in the maximum apparent canopy scale carboxylation rateV(CMAX,APP)(NSOL) when the soil relative extractable water content dropped below around 0.4. Concurrently, we found that the stomatal slope parameter (G(1), related to SOL) of the Medlynet al. unified optimization model linking vegetation conductance andGPPremained relatively constant. These results strengthen the increasing evidence that NSOL should be included in stomatal conductance/photosynthesis models to faithfully simulate bothGPPand water fluxes in forest ecosystems during severe drought. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.

ano.nymous@ccsd.cnrs.fr.invalid (Louis Gourlez de La Motte) 05 Oct 2020

https://hal.inrae.fr/hal-02957456v1

[hal-03040751] New developments in understanding plant water transport under drought stress

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ano.nymous@ccsd.cnrs.fr.invalid (Amanda A Cardoso) 04 Dec 2020

https://hal.inrae.fr/hal-03040751v1

[hal-03038558] Dernières innovations sur la plantation forestière. Contribution de la R&D pour accompagner les évolutions attendues dans les pratiques

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ano.nymous@ccsd.cnrs.fr.invalid (Catherine C. Collet) 03 Dec 2020

https://hal.inrae.fr/hal-03038558v1

[hal-02927318] How does contemporary selection shape oak phenotypes?

Most existing forests are subjected to natural and human-mediated selection pressures, which have increased due to climate change and the increasing needs of human societies for wood, fibre and fuel resources. It remains largely unknown how these pressures trigger evolutionary changes. We address this issue here for temperate European oaks (Quercus petraeaandQ. robur), which grow in mixed stands, under even-aged management regimes. We screened numerous functional traits for univariate selection gradients and for expected and observed genetic changes over two successive generations. In both species, growth, leaf morphology and physiology, and defence-related traits displayed significant selection gradients and predicted shifts, whereas phenology, water metabolism, structure and resilience-related traits did not. However, the direction of the selection response and the potential for adaptive evolution differed between the two species.Quercus petraeahad a much larger phenotypic and genetic variance of fitness thanQ. robur. This difference raises concerns about the adaptive response ofQ. roburto contemporary selection pressures. Our investigations suggest thatQ. roburwill probably decline steadily, particularly in mixed stands withQ. petraea, consistent with the contrasting demographic dynamics of the two species.

ano.nymous@ccsd.cnrs.fr.invalid (Hermine Alexandre) 01 Sep 2020

https://hal.inrae.fr/hal-02927318v1

[hal-02652095] Decreasing stand density favors resistance, resilience, and recovery of Quercus petraea trees to a severe drought, particularly on dry sites

Key message Decreasing stand density increases resistance, resilience, and recovery ofQuercus petraeatrees to severe drought (2003), particularly on dry sites, and the effect was independent of tree social status. Context Controlling competition is an advocated strategy to modulate the response of trees to predicted changes in climate. Aims We investigated the effects of stand density (low, medium, high; relative density index 0.20, 0.53, 1.04), social status (dominant, codominant, suppressed), and water balance (dry, mesic, wet; summer water balance - 182, - 126, - 96 mm) on the climate-growth relationships (1997-2012) and resistance (Rt), resilience (Rs), and recovery (Rc) following the 2003 drought. Methods Basal area increments were collected by coring (269 trees) in young stands (28 +/- 7.5 years in 2012) of sessile oak (Quercus petraea) in a French permanent network of silvicultural plots. Results We showed that the climate-growth relationships depend on average site-level water balance with trees highly dependent on spring and summer droughts on dry and mesic sites and not at all on wet sites. Neither stand density nor social status modulated mean response to climate. Decreasing stand density increased Rt, Rs, and Rc particularly on dry sites. The effect was independent of tree social position within the stand. Conclusion Reducing stand density mitigates more the effect of extreme drought events on drier sites than on wet sites.

ano.nymous@ccsd.cnrs.fr.invalid (Anna Schmitt) 14 Aug 2020

https://hal.inrae.fr/hal-02652095v1

[hal-03051411] Energy, water and carbon exchanges in managed forest ecosystems: description, sensitivity analysis and evaluation of the INRAE GO+ model, version 3.0

The mechanistic model GO+ describes the functioning and growth of managed forests based upon biophysical and biogeochemical processes. The biophysical and biogeochemical processes included are modelled using standard formulations of radiative transfer, convective heat exchange, evapotranspiration, photosynthesis, respiration, plant phenology, growth and mortality, biomass nutrient content, and soil carbon dynamics. The forest ecosystem is modelled as three layers, namely the tree overstorey, understorey and soil. The vegetation layers include stems, branches and foliage and are partitioned dynamically between sunlit and shaded fractions. The soil carbon submodel is an adaption of the Roth-C model to simulate the impact of forest operations. The model runs at an hourly time step. It represents a forest stand covering typically 1 ha and can be straightforwardly upscaled across gridded data at regional, country or continental levels. GO+ accounts for both the immediate and long-term impacts of forest operations on energy, water and carbon exchanges within the soil–vegetation–atmosphere continuum. It includes exhaustive and versatile descriptions of management operations (soil preparation, regeneration, vegetation control, selective thinning, clear-cutting, coppicing, etc.), thus permitting the effects of a wide variety of forest management strategies to be estimated: from close to nature to intensive. This paper examines the sensitivity of the model to its main parameters and estimates how errors in parameter values are propagated into the predicted values of its main output variables.The sensitivity analysis demonstrates an interaction between the sensitivity of variables, with the climate and soil hydraulic properties being dominant under dry conditions but the leaf biochemical properties being most influential with wet soil. The sensitivity profile of the model changes from short to long timescales due to the cumulative effects of the fluxes of carbon, energy and water on the stand growth and canopy structure. Apart from a few specific cases, the model simulations are close to the values of the observations of atmospheric exchanges, tree growth, and soil carbon and water stock changes monitored over Douglas fir, European beech and pine forests of different ages. We also illustrate the capacity of the GO+ model to simulate the provision of key ecosystem services, such as the long-term storage of carbon in biomass and soil under various management and climate scenarios.

ano.nymous@ccsd.cnrs.fr.invalid (Virginie Moreaux) 10 Dec 2020

https://hal.inrae.fr/hal-03051411v1

[hal-03179773] Temporal trends in tree defoliation and response to multiple biotic and abiotic stresses

The vitality of forests depends on multiple biotic and abiotic stresses that can act in an interactive way. Tree defoliation levels are therefore subject to long-term changes and shorter-term hazards that need to be monitored in the context of ongoing climate change. In this study, we analysed the combined effects of drought, insect attack and tree nutritional status on the level of defoliation in three major hardwood species in Europe: European beech (Fagus sylvatica), sessile oak (Quercus petraea) and pedunculate oak (Quercus robur). The forest condition data set was collected in the long-term intensive monitoring network in France (RENECOFOR). The average level of defoliation observed was 20% but varied considerably between plots and trees. From 1997 to 2015, beech defoliation worsened by 10% while oak defoliation stabilized over time. For the three tree species, crown defoliation was generally higher in the event of insect attack (increased by 2.6% to 7.5% depending on the tree species) and under drought (increased by 5.9%), while the effect of the tree nutritional statue was less consistent (from - 5.6% to + 10%) these factors acting synergistically. This study highlights the fact that the different stresses a tree species undergoes act in a complex and interactive way, with species-specific responses. In a context of increasing abiotic and biotic stresses, their combined analysis appears to be a necessity at a time when forest owners need to adapt their management to cope with climate change, particularly through the choice of tree species to be favoured in the future.

ano.nymous@ccsd.cnrs.fr.invalid (Maude Toïgo) 25 Aug 2022

https://hal.inrae.fr/hal-03179773v1

[hal-02963149] Le profil cultural : une méthode d'observation pour analyser les impacts de la préparation mécanisée du site sur la structure du sol

Face à la problématique du renouvellement forestier en stations contraignantes, la R&amp;D s’attache à concevoir, tester et évaluer des techniques appropriées de préparation mécanisée du sol avant plantation. L’évaluation s’appuie légitimement sur la survie et la croissance des plants. Mais pour interpréter les résultats, il faut aussi pouvoir caractériser et analyser les effets sur le sol et ses propriétés. C’est l’objet d’une méthode développée en agronomie et qu’on peut adapter au milieu forestier : le profil cultural. Voyons de quoi il s’agit.

ano.nymous@ccsd.cnrs.fr.invalid (Florian Vast) 14 Oct 2020

https://hal.science/hal-02963149v1

[hal-02544340] Comment l'Office national des forêts anticipe les effets du changement climatique ?

En charge de la gestion de onze millions d'hectares de forêts publiques, dont 4,6 millions d’hectares en métropole, l’Office national des forêts (ONF) est un acteur majeur de la filière forêt-bois en France. Depuis 2005, le changement climatique s’est imposé à l’ONF comme une priorité de recherche et de développement. Pour adapter les forêts au climat de demain et préserver les stocks de carbone, son département « Recherche développement et innovation » s’est rapproché des acteurs de la recherche en France. Dans cet article, les auteurs font le point des travaux et actions menés au cours des quatorze dernières années et de leur appropriation par les services de gestion.

ano.nymous@ccsd.cnrs.fr.invalid (Myriam Legay) 21 Apr 2020

https://hal.science/hal-02544340v1

[hal-03037487] Cultivation profile: a visual evaluation method of soil structure adapted to the analysis of the impacts of mechanical site preparation in forest plantations

Mechanical site preparation (MSP) is widely used in forestry to improve plantation success. Although it is known to alter soil properties, its direct effects on soil structure have rarely been described. The cultivation profile is a visual soil evaluation (VSE) method developed in agricultural research to analyse the impacts of cultivation practices on soil structure. The objective of the study was to adapt the method to forest plantations in order to analyse the effects of MSP on soil quality. Cultivation profiles were performed in six experimental plantation sites located in Northern France. The method made it possible to compare the impacts on soil structure of three MSP methods. It provided a schematic representation of the soil structural quality and a quantitative estimation of the volume of soil favourable to seedling root growth. It also highlighted unexpected negative effects of some MSP methods on soil structure, such as the creation of small cavities, the presence of compacted soil volumes due to wheel tracks or smeared soil volumes due to tool pass, and the pseudogleisation of soil zones due to changes in water circulation in the soil. The relevance and limitations of VSE methods in the context of forest plantation as well as the expected future development of the methods are discussed.

ano.nymous@ccsd.cnrs.fr.invalid (Catherine Collet) 03 Dec 2020

https://hal.inrae.fr/hal-03037487v1

[hal-02544285] La croissance des forêts et les changements environnementaux

Les forêts de l’hémisphère nord sont plus productives qu’il y a plusieurs décennies. Telle est la tendance observée et quantifiée dans différentes études menées depuis les années 1970 et qui mettent en cause plusieurs facteurs : les modifications des régimes pluviothermiques, les dépôts azotés et l’augmentation de la concentration atmosphérique en dioxyde de carbone. À partir de données de l’inventaire forestier national, les auteurs de cet article se sont penchéssur l’évolution des forêts françaises. Leurs résultats à des échelles plus fines mettent en évidence des variations extrêmes (négative et positive) liées aux espèces et au contexte environnemental local qu’il conviendrait de suivre en « temps réel » compte tenu des grandes incertitudes futures liées au climat.

ano.nymous@ccsd.cnrs.fr.invalid (François F. Lebourgeois) 21 Apr 2020

https://hal.science/hal-02544285v1

[hal-03038406] How does oak mast seeding affect the feeding behavior of sympatric red and roe deer?

Oak reproduction is characterized by mast seeding with high inter-annual fluctuations in fruit production. Such resource pulses can greatly affect ecosystem functioning and may cause seed consumers to alter their mobility, demography, or diet. Consequences of mast seeding for seed consumers remain poorly understood as their long timescale makes them difficult to study. We investigated impacts of oak mast seeding on the feeding behavior of two sympatric European deer species: red deer (Cervus elaphus) and roe deer (Capreolus capreolus). We analyzed their rumen content over a 31-year period in tandem with 10 years of data on oak fructification (i.e. 8 years of field monitoring and two modelled years). Acorn production is strongly correlated with consumption by both deer species. In years of high fructification, acorns represent more than 50% and 35% of red and roe deer diet, respectively, confirming assumptions that deer favor acorns when these are available. Red deer eat more acorns than roe deer both between and within years. High acorn production in mast years appears to saturate the capacity of deer to consume acorns. As the proportion of acorns increase in their diet, red deer eat more grasses and less conifer browse. No dietary shift was found for roe deer. By inducing dietary shifts in consumers, oak mast seeding can have cascading effects on ecosystem processes, notably on the damages on conifers caused by red deer and the consequences for forest dynamics.

ano.nymous@ccsd.cnrs.fr.invalid (Julien Barrere) 22 Aug 2022

https://hal.inrae.fr/hal-03038406v1

[hal-02870299] Which oak provenances for the 22nd century in Western Europe? Dendroclimatology in common gardens

The current distribution area of the two sympatric oaks Quercus petraea and Q. robur covers most of temperate Western Europe. Depending on their geographic location, populations of these trees are exposed to different climate constraints, to which they are adapted. Comparing the performances of trees from contrasting populations provides the insight into their expected resilience to future climate change required for forest management. In this study, the descendants of 24 Q. petraea and two Q. robur provenances selected from sites throughout Europe were grown for 20 years in three common gardens with contrasting climates. The 2420 sampled trees allowed the assessments of the relationship between radial growth and climate. An analysis of 15-year chronologies of ring widths, with different combinations of climate variables, revealed different response patterns between provenances and between common gardens. As expected, provenances originating from sites with wet summers displayed the strongest responses to summer drought, particularly in the driest common garden. All provenances displayed positive significant relationships between the temperature of the previous winter and radial growth when grown in the common garden experiencing the mildest winter temperatures. Only eastern provenances from continental cold climates also clearly expressed this limitation of growth by cold winter temperatures in the other two common gardens. However, ecological distance, calculated on the basis of differences in climate between the site of origin and the common garden, was not clearly related to the radial growth responses of the provenances. This suggests that the gradient of genetic variability among the selected provenances was not strictly structured according to climate gradients. Based on these results, we provide guidelines for forest managers for the assisted migration of Quercus petraea and Q. robur provenances.

ano.nymous@ccsd.cnrs.fr.invalid (Didier Bert) 08 Jan 2021

https://hal.science/hal-02870299v1

[hal-03040730] In situ estimation of genetic variation of functional and ecological traits in Quercus petraea and Q. robur

Predicting the evolutionary potential of natural tree populations requires the estimation of heritability and genetic correlations among traits on which selection acts, as differences in evolutionary success between species may rely on differences for these genetic parameters. In situ estimates are expected to be more accurate than measures done under controlled conditions which do not reflect the natural environmental variance. The aim of the current study was to estimate three genetic parameters (i.e., heritability, evolvability, and genetic correlations) in a natural mixed oak stand composed of Quercus petraea and Quercus robur about 100 years old, for 58 traits of ecological, and functional relevance (growth, reproduction, phenology, physiology, resilience, structure, morphology, and defense). First, we estimated genetic parameters directly in situ using realized genomic relatedness of adult trees and parentage relationships over two generations to estimate the traits' additive variance. Secondly, we benefited from existing ex situ experiments (progeny tests and conservation collection) installed with the same populations, thus allowing comparisons of in situ heritability estimates with more traditional methods. Heritability and evolvability estimates obtained with different methods varied substantially and showed large confidence intervals; however, we found that in situ were less precise than ex situ estimates, and assessments over two generations (with deeper relatedness) improved estimates of heritability while large sampling sizes are needed for accurate estimations. At the biological level, heritability values varied moderately across different ecological and functional categories of traits, and genetic correlations among traits were conserved over the two species. We identified limits for using realized genomic relatedness in natural stands to estimate the genetic variance, given the overall low variance of genetic relatedness and the rather low sampling sizes of currently used long-term genetic plots in forestry. These limits can be overcome if larger sample sizes are considered, or if the approach is extended over the next generation.

ano.nymous@ccsd.cnrs.fr.invalid (Hermine Alexandre) 16 Sep 2024

https://hal.inrae.fr/hal-03040730v1

[hal-03048253] Vegetation unit assignments: phytosociology experts and classification programs show similar performance but low convergence

Aims: Assigning vegetation plots to vegetation units is a key step in biodiversity management projects. Nevertheless, the process of plot assignment to types is usually non-standardized, and assignment consistency remains poorly explored. To date, the efficiency of automatic classification programs has been assessed by comparing them with a unique expert judgment. Therefore, we investigated the consistency of five phytosociology expert judgments, and the consistency of these judgements with those of automatic classification programs. Location: Mainland France. Methods: We used 273 vegetation plots distributed across France and covering the diversity of the temperate and mountainous forest ecosystems of Western Europe. We asked a representative panel of five French organizations with recognized expertise in phytosociology to assign each plot to vegetation units. We provided a phytosociological classification including 228 associations, 43 alliances and eight classes. The assignments were compared among experts using an agreement ratio. We then compared the assignments suggested by three automatic classification programs with the expert judgments. Results: We observed small differences among the agreement ratios of the expert organizations; a given expert organization agreed with another one on association assignment one time in four on average, and one time in two on alliance assignment. The agreement ratios of the automatic classification programs were globally lower, but close to expert judgments. Conclusions: The results support the current trend toward unifying the existing classifications and specifying the assignment rules by creating guiding tools, which will decrease inter-observer variation. As compared to a pool of phytosociology experts, programs perform similarly to individual experts in vegetation unit assignment, especially at the alliance level. Although programs still need to be improved, these results pave the way for the creation of habitat time series crucial for the monitoring and conservation of biodiversity.

ano.nymous@ccsd.cnrs.fr.invalid (Lise Maciejewski) 03 May 2022

https://hal.science/hal-03048253v1

[hal-03038588] Evaluation de l’intérêt d’une préparation mécanisée, résultats d’un essai de semis artificiel de Pin sylvestre dans les Vosges.

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ano.nymous@ccsd.cnrs.fr.invalid (Jonathan Pitaud) 03 Dec 2020

https://hal.inrae.fr/hal-03038588v1

[hal-02989071] Gestion forestière intégrée des insectes ravageurs : exemple par l’étude de la niche écologique du hanneton forestier (Melolontha hippocastani Fabr. 1801)

Depuis une dizaine d’années, nous observons une recrudescence de dégâts imputables au hanneton forestier (Melolontha hippocastani) dans différentes forêts françaises. Ils consomment les racines et causent la mort des semis et plants forestiers et sont suspectés d’être un facteur supplémentaire de dépérissement forestier. Dans ce cadre, trois études ont été mises en œuvre dans les forêts des Vosges du Nord, en 2014, 2018 et 2019. Cet article cherche à synthétiser les résultats obtenus. Il apparaît que les sols sableux sont les plus favorables à l’espèce. Par ailleurs, le couvert dense de la strate arbustive basse induit des effets négatifs sur la ponte des œufs. D’autre part, les peuplements mélangés (feuillus-résineux) à prépondérance de chênes sont les plus favorables à un grand nombre de pontes et de larves dans le sol. Enfin, l’ouverture de la cano- pée semble jouer un rôle positif sur le choix du lieu de ponte. Nous discutons en fin d’article sur les règles sylvicoles pouvant être préconisées.

ano.nymous@ccsd.cnrs.fr.invalid (Jérémy Cours) 12 Aug 2021

https://hal.science/hal-02989071v1

[hal-03048264] EUNIS Habitat Classification: Expert system, characteristic species combinations and distribution maps of European habitats

Aim: The EUNIS Habitat Classification is a widely used reference framework for European habitat types (habitats), but it lacks formal definitions of individual habitats that would enable their unequivocal identification. Our goal was to develop a tool for assigning vegetation-plot records to the habitats of the EUNIS system, use it to classify a European vegetation-plot database, and compile statistically-derived characteristic species combinations and distribution maps for these habitats. Location: Europe. Methods: We developed the classification expert system EUNIS-ESy, which contains definitions of individual EUNIS habitats based on their species composition and geographic location. Each habitat was formally defined as a formula in a computer language combining algebraic and set-theoretic concepts with formal logical operators. We applied this expert system to classify 1,261,373 vegetation plots from the European Vegetation Archive (EVA) and other databases. Then we determined diagnostic, constant and dominant species for each habitat by calculating species-to-habitat fidelity and constancy (occurrence frequency) in the classified data set. Finally, we mapped the plot locations for each habitat. Results: Formal definitions were developed for 199 habitats at Level 3 of the EUNIS hierarchy, including 25 coastal, 18 wetland, 55 grassland, 43 shrubland, 46 forest and 12 man-made habitats. The expert system classified 1,125,121 vegetation plots to these habitat groups and 73,188 to other habitats, while 63,064 plots remained unclassified or were classified to more than one habitat. Data on each habitat were summarized in factsheets containing habitat description, distribution map, corresponding syntaxa and characteristic species combination. Conclusions: EUNIS habitats were characterized for the first time in terms of their species composition and distribution, based on a classification of a European database of vegetation plots using the newly developed electronic expert system EUNIS-ESy. The data provided and the expert system have considerable potential for future use in European nature conservation planning, monitoring and assessment.

ano.nymous@ccsd.cnrs.fr.invalid (Milan Chytrý) 09 Dec 2020

https://hal.science/hal-03048264v1

[hal-03045938] Natura 2000 forest habitats: climatic debt in lowlands and thermophilization in highlands

Natura 2000 is a European network of sites dedicated to the conservation of vulnerable habitats. The definitions of Natura 2000 habitats are mainly based on plant communities. We investigated if the increase of the dominance of warm-adapted species observed in plant communities, described as thermophilization, had already led to measurable changes in Natura 2000 forest habitats. We created 5701 pairs of neighboring forest plots by gathering plots surveyed before 1987 and after 1997 to reflect historical and recent climatic conditions. A Natura 2000 habitat type was assigned to each vegetation plot using an automatic classification program. We calculated a temperature index that synthesized the temperature range of each habitat, and compared the habitat temperature indexes of the recent and historical plots of each pair. We highlighted a significant overall shift of 4.8% ± 1.78 (CI 95%) of the pairs toward warmer habitats over the studied period. While the shift was not significant in lowlands, 11.1% ± 3.0 (CI 95%) of the pairs evolved toward warmer habitats in highlands. The excess of pairs with a warmer habitat in the recent period was interpreted as thermophilization of Natura 2000 forest habitats. Therefore, global warming has been strong enough to induce actual changes at the coarse-grained habitat resolution specifically targeted by public policies. The absence of significant results in lowlands suggests the existence of unrealized potential habitat changes, which can be considered as a climatic debt. These results call for differential prioritization levels and implementations of public policies for nature conservation in lowlands and highlands.

ano.nymous@ccsd.cnrs.fr.invalid (Lise Maciejewski) 21 Apr 2023

https://hal.science/hal-03045938v1

[hal-02610246] Species mixing reduces drought susceptibility of Scots pine (Pinus sylvestris L.) and oak (Quercus robur L., Quercus petraea (Matt.) Liebl.) - Site water supply and fertility modify the mixing effect

Tree species mixing has been widely promoted as a promising silvicultural tool for reducing drought stress. However, so far only a limited number of species combinations have been studied in detail, revealing inconsistent results. In this study, we analysed the effect of mixing Scots pine and oak (pedunculate oak and sessile oak) trees on their drought response along a comprehensive ecological gradient across Europe. The objective was to improve our knowledge of general drought response patterns of two fundamental European tree species in mixed versus monospecific stands. We focused on three null hypotheses: (HI) tree drought response does not differ between Scots pine and oak, (HII) tree drought response of Scots pine and oak is not affected by stand composition (mixture versus monoculture) and (HIII) tree drought response of Scots pine and oak in mixtures and monocultures is not modified by tree size or site conditions. To test the hypotheses, we analysed increment cores of Scots pine and oak, sampled in mixed and monospecific stands, covering a wide range of site conditions. We investigated resistance (the ability to maintain growth levels during drought), recovery (the ability to restore a level of growth after drought) and resilience (the capacity to recover to pre-drought growth levels), involving sitespecific drought events that occurred between 1976 and 2015. In monocultures, oak showed a higher resistance and resilience than Scots pine, while recovery was lower. Scots pine in mixed stands exhibited a higher resistance, but also a lower recovery compared with Scots pine in monocultures. Mixing increased the resistance and resilience of oak. Ecological factors such as tree size, site water supply and site fertility were found to have significant effects on the drought response. In the case of Scots pine, resistance was increased by tree size, while recovery was lowered. Resistance of oak increased with site water supply. The observed mixing effect on the tree drought response of Scots pine and oak was in some cases modified by the site conditions studied. Positive mixing effects in terms of resistance and resilience of oak increased with site water supply, while the opposite was found regarding recovery. In contrast, site fertility lessened the positive mixing effect on the resistance of Scots pine. We hypothesise that the observed positive mixing effects under drought mainly result from waterand/or light-related species interactions that improve resource availability and uptake according to temporal and spatial variations in environmental conditions.

ano.nymous@ccsd.cnrs.fr.invalid (M. Steckel) 16 May 2020

https://hal.inrae.fr/hal-02610246v1

[hal-02949790] A standard protocol for reporting species distribution models

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ano.nymous@ccsd.cnrs.fr.invalid (Damaris Zurell) 12 Nov 2020

https://hal.inrae.fr/hal-02949790v1

[hal-03317972] Ancient forest statistics provide centennial perspective over the status and dynamics of forest area in France

Context: The history of European forest dynamic remains fragmental. In France, the Daubrée statistics (1908) and agricultural statistics (1892, 1929) formed fundamental material to fill this gap. Aims: Release, test, and summarize the digitalized dataset. Analyze long-term forest changes in forest area, composition, and structure. Methods: Primary data on forest area across NUTS-3 geographic units, split by forest management and ownership categories and dominating tree species (Daubrée), were digitized and cross-compared. Centennial changes in forest attributes were assessed from modern forest inventory data. Results: Cross-comparison revealed: (1) strong temporal consistency in forest changes over time, (2) systematic and interpretable biases in ownership/management categories between Daubrée and agricultural statistics. Strong shift from coppices to high forests, increased prevalence of private ownership, and constant proportion of broadleaf- and conifer-dominated forests were highlighted, with increased tree species diversity at country scale. Conclusion: Ancient statistics are shown to play a major role in retrospective land-use and forest policy analysis.

ano.nymous@ccsd.cnrs.fr.invalid (Timothée Audinot) 09 Aug 2021

https://hal.science/hal-03317972v1

[hal-02948750] Validation of Space-based albedo products from upscaled tower-based measurements over Heterogeneous and Homogeneous landscapes

Surface albedo is a fundamental radiative parameter as it controls the Earth’s energy budget and directly affects the Earth’s climate. Satellite observations have long been used to capture the temporal and spatial variations of surface albedo because of their continuous global coverage. However, space-based albedo products are often affected by errors in the atmospheric correction, multi-angular bi-directional reflectance distribution function (BRDF) modelling, as well as spectral conversions. To validate space-based albedo products, an in situ tower albedometer is often used to provide continuous “ground truth” measurements of surface albedo over an extended area. Since space-based albedo and tower-measured albedo are produced at different spatial scales, they can be directly compared only for specific homogeneous land surfaces. However, most land surfaces are inherently heterogeneous with surface properties that vary over a wide range of spatial scales. In this work, tower-measured albedo products, including both directional hemispherical reflectance (DHR) and bi-hemispherical reflectance (BHR), are upscaled to coarse satellite spatial resolutions using a new method. This strategy uses high-resolution satellite derived surface albedos to fill the gaps between the albedometer’s field-of-view (FoV) and coarse satellite scales. The high-resolution surface albedo is generated from a combination of surface reflectance retrieved from high-resolution Earth Observation (HR-EO) data and moderate resolution imaging spectroradiometer (MODIS) BRDF climatology over a larger area. We implemented a recently developed atmospheric correction method, the Sensor Invariant Atmospheric Correction (SIAC), to retrieve surface reflectance from HR-EO (e.g., Sentinel-2 and Landsat-8) top-of-atmosphere (TOA) reflectance measurements. This SIAC processing provides an estimated uncertainty for the retrieved surface spectral reflectance at the HR-EO pixel level and shows excellent agreement with the standard Landsat 8 Surface Reflectance Code (LaSRC) in retrieving Landsat-8 surface reflectance. Atmospheric correction of Sentinel-2 data is vastly improved by SIAC when compared against the use of in situ AErosol RObotic NETwork (AERONET) data. Based on this, we can trace the uncertainty of tower-measured albedo during its propagation through high-resolution EO measurements up to coarse satellite scales. These upscaled albedo products can then be compared with space-based albedo products over heterogeneous land surfaces. In this study, both tower-measured albedo and upscaled albedo products are examined at Ground Based Observation for Validation (GbOV) stations (https://land.copernicus.eu/global/gbov/), and used to compare with satellite observations, including Copernicus Global Land Service (CGLS) based on ProbaV and VEGETATION 2 data, MODIS and multi-angle imaging spectroradiometer (MISR).

ano.nymous@ccsd.cnrs.fr.invalid (Rui Song) 25 Oct 2023

https://hal.inrae.fr/hal-02948750v1

[hal-02948747] Contrasting patterns of tree species mixture effects on wood δ13C along an environmental gradient

Establishing mixed-species stands is frequently proposed as a strategy to adapt forests to the increasing risk of water scarcity, yet contrasted results have been reported regarding mixing effects on tree drought exposure. To investigate the drivers behind the spatial and temporal variation in water-related mixing effects, we analysed the delta C-13 variation in 22-year tree ring chronologies for beech and pine trees sampled from 17 pure and mixed pine-beech stands across a large gradient of environmental conditions throughout Europe. In the pure stands, average delta C-13 values were lower for beech (-27.9 parts per thousand to -22.2 parts per thousand) than for pine (-26.0 parts per thousand to -21.1 parts per thousand), irrespective of site conditions. Decreasing SPEI values (calculated over June to September) were associated with an increase in delta C-13 for both species, but their effect was influenced by stand basal area for pine and site water availability for beech. Mixing did not change the temporal constancy of delta C-13 nor the tree reaction to a drought event, for any of the species. While the mixing effect (Delta delta C-13 = delta C-13 pure stands - delta C-13 mixed stands) was on average positive for beech and non-significant for pine across the whole gradient, this effect strongly differed between sites. For both species, mixing was not significant at extremely dry sites and positive at dry sites; on moderately wet sites, mixing was positive for beech and negative for pine; at sites with permanent water supply, no general patterns emerge for any of the species. The pattern of mixing effect along the gradient of water availability was not linear but showed threshold points, highlighting the need to investigate such relation for other combinations of tree species.

ano.nymous@ccsd.cnrs.fr.invalid (G. de Streel) 25 Oct 2023

https://hal.inrae.fr/hal-02948747v1

[hal-02934348] Sacrificing growth and maintaining a dynamic carbohydrate storage are key processes for promoting beech survival under prolonged drought conditions

Key message In case of a prolonged drought, the stored carbohydrates in trees were remobilized to fuel survival functions until their nearly depletion at death stage. Abstract Dynamic global vegetation models project forest tree mortality in response to the recurrent severe droughts likely in the future. However, these models should better take into account the physiological processes involved in tree mortality. Faced with severe drought, the Fagus sylvatica L. tree strongly limits its cambial growth. This suggests that readjustments in carbon (C) allocation among sink functions are taking place in response to the lack of water and this could allow tree's survival. For 3 years, we induced a water shortage on 8-year-old beech trees in a rain exclusion system. During this period, we analysed the consequences of severe drought on survival rate, growth, and non-structural carbohydrate (NSC) dynamics in the aboveground and belowground compartments of control, water-stressed living, and dead trees. The survival rate after 3 years of drought was 87%, while primary and secondary growth was strongly reduced. The first 2 years, NSC concentrations increased in all tree compartments (stem, branches, and roots) in response to drought. However, during the third year, starch dropped markedly in water-stressed trees, while soluble sugar concentrations remained similar to control trees. All the compartments in dead trees were virtually empty of starch and soluble sugars. Maintaining an active C storage function at the expense of growth was certainly key to F. sylvatica survival under prolonged extreme drought conditions. Process-based models predicting mortality should better take into account C storage and remobilization processes in forest trees.

ano.nymous@ccsd.cnrs.fr.invalid (Pierre-Antoine Chuste) 09 Sep 2020

https://hal.science/hal-02934348v1

[hal-02948828] Microgeographic local adaptation and ecotype distributions: The role of selective processes on early life‐history traits in sympatric, ecologically divergent Symphonia populations

Trees are characterized by the large number of seeds they produce. Although most of those seeds will never germinate, plenty will. Of those which germinate, many die young, and eventually, only a minute fraction will grow to adult stage and reproduce. Is this just a random process? Do variations in germination and survival at very young stages rely on variations in adaptations to microgeographic heterogeneity? and do these processes matter at all in determining tree species distribution and abundance?We have studied these questions with the Neotropical Symphonia tree species. In the Guiana shield, Symphonia are represented by at least two sympatric taxa or ecotypes, Symphonia globulifera found almost exclusively in bottomlands, and a yet undescribed more generalist taxon/ecotype, Symphonia sp1. A reciprocal transplantation experiment (510 seeds, 16 conditions) was set up and followed over the course of 6 years to evaluate the survival and performance of individuals from different ecotypes and provenances.Germination, survival, growth, and herbivory showed signs of local adaptation, with some combinations of ecotypes and provenances growing faster and surviving better in their own habitat or provenance region. S. globulifera was strongly penalized when planted outside its home habitat but showed the fastest growth rates when planted in its home habitat, suggesting it is a specialist of a high‐risk high‐gain strategy. Conversely, S. sp1 behaved as a generalist, performing well in a variety of environments.The differential performance of seeds and seedlings in the different habitats matches the known distribution of both ecotypes, indicating that environmental filtering at the very early stages can be a key determinant of tree species distributions, even at the microgeographic level and among very closely related taxa. Furthermore, such differential performance also contributes to explain, in part, the maintenance of the different Symphonia ecotypes living in intimate sympatry despite occasional gene flow.

ano.nymous@ccsd.cnrs.fr.invalid (Niklas Tysklind) 30 Sep 2020

https://hal.science/hal-02948828v1

[hal-02504844] Selective and taxon-dependent effects of semi-feral cattle grazing on tree regeneration in an old-growth Mediterranean mountain forest

[...]

ano.nymous@ccsd.cnrs.fr.invalid (Xavier Fortuny) 11 Mar 2020

https://univ-lyon1.hal.science/hal-02504844v1

[hal-03043585] Traits controlling shade tolerance in tropical montane trees

Tropical canopies are complex, with multiple canopy layers and pronounced gap dynamics contributing to their high species diversity and productivity. An important reason for this complexity is the large variation in shade tolerance among di erent tree species. At present, we lack a clear understanding of which plant traits control this variation, e.g., regarding the relative contributions of whole-plant versus leaf traits or structural versus physiological traits. We investigated a broad range of traits in six tropical montane rainforest tree species with di erent degrees of shade tolerance, grown under three di erent radiation regimes (under the open sky or beneath sparse or dense canopies). The two distinct shade-tolerant species had higher fractional biomass in leaves and branches while shade-intolerant species invested more into stems, and these di erences were greater under low radiation. Leaf respiration and photosynthetic light compensation point did not vary with species shade tolerance, regardless of radiation regime. Leaf temperatures in open plots were markedly higher in shade-tolerant species due to their low transpiration rates and large leaf sizes. Our results suggest that interspeci c variation in shade tolerance of tropical montane trees is controlled by species di erences in whole-plant biomass allocation strategy rather than by di erence in physiological leaf traits determining leaf carbon balance at low radiation.

ano.nymous@ccsd.cnrs.fr.invalid (Elisée Bahati Ntawuhiganayo) 07 Dec 2020

https://hal.science/hal-03043585v1

[hal-02975249] Early effects of temperate agroforestry practices on soil organic matter and microbial enzyme activity

Aims: A field experiment was conducted to evaluate the effects of alley cropping systems on microbial activity and soil organic matter (SOM) pools. We hypothesized that enzyme activity and labile pools of SOM are early and sensitive indicators of changes induced by tree introduction in the cropping systems. Methods: Poplar-alfalfa and alder-gramineous (cereal or ryegrass) associations and their respective control systems (alfalfa and gramineous) were compared in terms of soil carbon (C), nitrogen (N) and water contents, SOM labile pools, NIRS-MIRS spectra and microbial enzyme activity in the topsoil (0–15 cm) for 4 years after tree planting. Results: After 1 year, tree introduction induced a decrease in soil water content, microbial biomass N and some enzyme activities under alfalfa system. After 4 years, tree introduction resulted in higher soil water contents in both systems (alfalfa and gramineous); higher microbial biomass N and lower C:N in alfalfa-poplar plots compared to control plots. MIRS-NIRS analyses showed a greatest differentiation in SOM quality between alfalfa-based systems. Conclusions: The effects of temperate agroforestry systems on SOC in the topsoil are relatively weak in the first years after tree introduction. Observed effects were more pronounced in the alfalfa-poplar system, probably due to higher tree growth. Further studies will provide insights into the longer-term effects of these systems on soil functioning.

ano.nymous@ccsd.cnrs.fr.invalid (Hugues Clivot) 26 Apr 2022

https://hal.science/hal-02975249v1

[hal-02527995] Distribution of soil properties along forest-grassland interfaces: Influence of permanent environmental factors or land-use after-effects?

Soil properties vary spatially according to land use; both because land users have selected specific soil properties for specific land uses, and land uses modify the soil properties. However, permanent environment factors and land-use effects are unlikely to display the exact same spatial patterns. Study of the spatial and historical patterns of distribution of soil properties could help to separate between these two causes. In this aim, we studied 22 forest-grassland interfaces with controlled historical configurations in northeast France. In each land use (forest and grassland), three distances to the edge (edge, periphery and core) and two land-use histories (ancient and recent) were studied.Along forest-grassland interfaces, forests were usually located slightly upslope of grasslands, and mainly because this non-random topographic position the topsoil texture was significantly more silty in forests, and clayey in grasslands. After statistically controlling for the effects of topography and soil texture, we observed two main gradients of variation in soil properties according to the distance-to-edge (acidity in forest and nutrient content in grassland). In forest, pH and Ca dropped from the edges to the peripheries (15 m distance), while in grassland, C, N, P and Na sharply increased from the edges to the cores (25 m distance). These results demonstrate, through the edge effect, the strong influence of the land use on a part of soil properties. Furthermore, less than two centuries after grassland afforestation or deforestation, we observed that soil properties in recent forests and recent grasslands were respectively closer to their current land use than to their former land use. These results demonstrate a rapid change in soil properties after land-use change. However, recent forests and recent grasslands kept a legacy of soil texture from their former land use, respectively. Recent grasslands also kept a lower soil density, N and Na content compared to ancient grasslands.Hence, this study of forest-grassland interfaces show strong and short-scale relationships between land use and soil properties and suggest that they express both original choices of land users for specific soil properties and land-use after-effects. The non-random topographic position of the forest-grassland interfaces indicates a conscious choice of this positioning by the land users, for agronomic reasons. Beyond that, land use, through vegetation composition and management practices, also has a strong impact on soil properties. The fact that land-use changes affect most soil properties after only a few decades confirms the existence of land-use effects over time.

ano.nymous@ccsd.cnrs.fr.invalid (Maxime Burst) 21 Dec 2021

https://hal.inrae.fr/hal-02527995v1

[hal-03209300] Reply to Elmendorf and Ettinger: Photoperiod plays a dominant and irreplaceable role in triggering secondary growth resumption

[...]

ano.nymous@ccsd.cnrs.fr.invalid (Jian-Guo Huang) 27 Apr 2021

https://hal.inrae.fr/hal-03209300v1

[hal-03085655] Unprecedented pluri-decennial increase in the growing stock of French forests is persistent and dominated by private broadleaved forests

& Key message French forests exhibit the fastest relative changes across Europe. Growing stock increases faster than area, and is greatest in low-stocked private broadleaved forests. Past areal increases and current GS levels show positive effects on GS expansion, with GS increases hence expected to persist. & Context Strong increases in growing stocks (GS) of European forests for decades remain poorly understood and of unknown duration. French forests showing the greatest relative changes across Europe form the investigated case study. & Aims The magnitudes of net area, GS, and GS density (GSD) changes were evaluated across forest categories reflecting forest policy and land-use drivers. The roles of forest areal changes, GS and GSD levels on GS changes were investigated. & Methods National Forest Inventory data were used to produce time series of area, GS and GSD across forest categories over 1976–2014, and exploratory causal models of GS changes. & Results GS (+ 57%) increased three times faster than area, highlighting an advanced stage in the forest transition. Low-stocked private forests exhibited strong changes in GS/GSD, greatest in private broadleaved forests, stressing the contribution of returning forests on abandoned lands. Regression models demonstrated positive effects of both past areal increases and current GS, on GS expansion. & Conclusion Aerial C-sink in French forests is expected to persist in future decades.

ano.nymous@ccsd.cnrs.fr.invalid (Jean-Daniel Bontemps) 21 Dec 2020

https://hal.science/hal-03085655v1

[hal-02948752] Lack of effect of admixture proportion and tree density on water acquisition depth for European beech (Fagus sylvatica L.) and sycamore maple (Acer pseudoplatanus L.)

AbstractKey messageIn a mixed,Fagus sylvaticaL.-Acer pseudoplatanusL., young plantation, trees of both species absorbed water from superficial soil layers despite the presence of roots and water in deeper layers. Admixture proportion and tree density were weak predictors of water acquisition depth, as well as fine root vertical distribution, although it might be due to distinct periods of root and isotope investigations.ContextPromoting mixed forests and reducing stand densities have been proposed as effective ways to maintain the productivity of temperate planted forest stands in a changing climate.AimsThe objective of this study was to analyse how stand density and the degree of admixture of European beech and sycamore maple interactively influenced the water acquisition profile of individual trees.MethodsWe used a stable isotope (deuterium) approach to determine the profiles of soil water acquisition of both species in a 16-year-old plantation where trees had been planted along crossed gradients of tree density and species proportion. The profiles were then compared with the vertical distribution of fine root of these species in the plantation.ResultsAll the target trees mostly absorbed soil water from the first few centimetres of soil despite homogenous vertical water availability and the fact that a great part of the fine root biomass was located below 10 cm. Admixture proportion and tree density had negligible effects on soil water acquisition depth.ConclusionNo vertical differentiation of soil water acquisition between the two species was observed, suggesting that mixing these species does not promote reduction of belowground competition for resource acquisition. The vertical distribution of fine root may be a weak predictor of water acquisition depth.

ano.nymous@ccsd.cnrs.fr.invalid (Alexandre Fruleux) 05 Apr 2021

https://hal.inrae.fr/hal-02948752v1

[hal-02549007] Limiting factors of aspen radial growth along a climatic and soil water budget gradient in south-western Siberia

Understanding how climate and soil hydrology control tree growth is critical to predict the response of Siberian ecosystems to climate change. The general aim of this study was to (i) characterize the soil water budget and identify the factors controlling aspen (Populus tremula L.) radial growth in south-western Siberia, and (ii) assess its potential response to future climate change. Along a gradient of climate and soil hydrological conditions, soil water budgets were reconstructed by modeling at four sites, and dendrochronological analyses were performed. Aspen growth potential was simulated in response to different climate change scenarios represented by shifts in soil water budgets. Simulated soil water budgets varied with climate variables, specifically increased temperature and drier summer combined with varying winter precipitation occurring as snowfall.. We show that plant-available soil water and drainage gradually increased while stress decreased from the warmest and driest (south, forest-steppe zone) site to the coldest and wettest (north, southern taiga zone) site. Aspen radial growth was mainly limited by summer temperature in the north and by summer water deficit in the south. Surprisingly, we did not find clear evidence of snow level impact on radial growth, either positively in the south (water supply and protection against soil freezing) or negatively in the north (water-logging and drainage). In the context of climate change, water stress intensity could increase dramatically in the south inhibiting aspen growth; in those places summer soil water content depends on the refilling that occurs at snow-melt and increasing winter precipitation could alleviate stress levels. Conversely, in the north, aspen growth may mostly benefit from rising temperature.

ano.nymous@ccsd.cnrs.fr.invalid (Félix Bredoire) 21 Apr 2020

https://hal.inrae.fr/hal-02549007v1

[hal-03273202] Effet de la hauteur de prélèvement sur la composition quantitative et qualitative des polyphénols de l’écorce d’Abies alba Mill.

L’écorce de résineux, cultivés dans un but commercial, est une source potentielle précieuse de métabolites secondaires tels que les polyphénols. Les tannins, qui font partie des polyphénols présents dans l’écorce, sont utilisés dans la fabrication d’adhésifs et de résines, mais également en tant qu’agent de tannage, antibactérien, antifongique, antitermite et antioxydant. Peu d’informations existent à propos du rendement et de la composition des extraits d’écorce en fonction de la hauteur de l’échantillon prélevé dans le tronc ainsi qu’en fonction de la présence ou l’absence de branches. Cette étude a pour but d’examiner la variabilité des métabolites secondaires présents dans l’écorce d’Abies alba à la fois en fonction de la hauteur de l’échantillon prélevé dans un arbre, mais également la variabilité présente à des hauteurs spécifiques entre plusieurs arbres. La finalité de cette étude est de déterminer quelle fraction d’écorce contient le plus d’extractibles chez cette essence. Pour cela, huit arbres ont été sélectionnés dans lesquels un maximum de treize disques a été coupé tout le long du tronc. Ces échantillons ont été prélevés en bas du tronc à une hauteur de 30 cm du sol puis à différentes hauteurs Ces différentes hauteurs ont été choisies pour des raisons industrielles (hauteur limite pour le bois d’œuvre ou pour l’utilisation industrielle) mais également pour des raisons physiologiques (hauteur à la base du houppier, hauteur de la première branche verte…). Les échantillons prélevés ont été broyés puis extraits avec un mélange eau/éthanol (1 :1, v/v) en réalisant une extraction accélérée à chaud et sous pression. Une première étude quantitative est réalisée pour connaître la quantité d’extractibles totale présente dans l’écorce. La seconde étude est qualitative, afin de connaître quels types d’extractibles sont présents dans ces écorces. Ces extraits ont donc été examinés par chromatographie liquide couplée à un spectromètre UV-visible et un spectromètre de masse .Les résultats ont montré que la composition de l’extrait total d’écorce augmente en même temps que la hauteur dans le tronc. La proportion la plus élevée en composés polyphénoliques se trouve dans la section inférieure sous la couronne.

ano.nymous@ccsd.cnrs.fr.invalid (Pauline Gérardin) 29 Jun 2021

https://agroparistech.hal.science/hal-03273202v1

[hal-03046910] Do tree rings record changes in soil fertility? Results from a Quercus petraea fertilization trial

Through the variations in their dimension, density, anatomy or isotopes composition, tree rings have provided invaluable proxies to evaluate past changes in the environment. Whereas long-term records of changes in soil fertility are particularly desired for forest ecosystem studies, the use of the chemical composition of tree rings as potential marker is still controversial. Dendrochemistry has sometimes been considered as a promising approach to study past changes in soil chemistry, whereas some authors stated that element translocations in the wood preclude any possibility of reliable retrospective monitoring. Here, we aimed at testing whether the wood elemental content of fertilized oaks (Quercus petraea) differed from control trees >30 years after a NPKCaMg fertilization and, if so, if the date of fertilization could be retrieved from the ring analysis. The contents in N, Mg, P, K, Ca and Mn were measured for each of the 43 sampled trees and in every ring of the 58-year long chronology with a non-destructive method coupling a Wavelength Dispersive Spectroscope (WDS) with a Scanning Electron Microscope (SEM).The results showed significantly higher contents in Ca and lower contents in Mn in fertilized compared to control trees. However, there was no difference in elemental content between the rings of the fertilized trees built in the 20 years before and those built after fertilization. Thus, whereas the effect of fertilization on increasing ring width was dramatic, immediate and relatively short-lasting, the elemental composition of the entire ring sequence was impacted, precluding the dating of the event. These results question the possibility to reconstruct long-term changes in soil fertility based on dendrochemistry.

ano.nymous@ccsd.cnrs.fr.invalid (Maxime Durand) 07 Mar 2022

https://hal.inrae.fr/hal-03046910v1

[hal-02942642] Sensitivity of gross primary productivity to climatic drivers during the summer drought of 2018 in Europe

In summer 2018, Europe experienced a record drought, but it remains unknown how the drought affected ecosystem carbon dynamics. Using observations from 34 eddy covariance sites in different biomes across Europe, we studied the sensitivity of gross primary productivity (GPP) to environmental drivers during the summer drought of 2018 versus the reference summer of 2016. We found a greater drought-induced decline of summer GPP in grass- lands (−38%) than in forests (−10%), which coincided with reduced evapotranspiration and soil water content (SWC). As com- pared to the ‘normal year’ of 2016, GPP in different ecosystems exhibited more negative sensitivity to summer air temperature (Ta) but stronger positive sensitivity to SWC during summer drought in 2018, that is, a stronger reduction of GPP with soil moisture deficit. We found larger negative effects of Ta and vapour pressure deficit (VPD) but a lower positive effect of photosynthetic photon flux density on GPP in 2018 compared to 2016, which contributed to reduced summer GPP in 2018. Our results demonstrate that high temperature-induced increases in VPD and decreases in SWC aggravated drought impacts on GPP.

ano.nymous@ccsd.cnrs.fr.invalid (Zheng Fu) 18 Sep 2020

https://hal.inrae.fr/hal-02942642v1

[hal-02931277] A Machine-Learning Approach for Classifying Defects on Tree Trunks using Terrestrial LiDAR

Three-dimensional data are increasingly prevalent in forestry thanks to terrestrial LiDAR. This work assesses the feasibility for an automated recognition of the type of local defects present on the bark surface. These sin-gularities are frequently external markers of inner defects affecting wood quality, and their type, size, and frequency are major components of grading rules. The proposed approach assigns previously detected abnormalities in the bark roughness to one of the defect types: branches, branch scars, epi-cormic shoots, burls, and smaller defects. Our machine learning approach is based on random forests using potential defects shape descriptors, including Hu invariant moments, dimensions, and species. The results of our experiments involving different French commercial species, oak, beech, fir, and pine showed that most defects were well classified with an average F 1 score of 0.86.

ano.nymous@ccsd.cnrs.fr.invalid (Van-Tho Nguyen) 05 Sep 2020

https://hal.science/hal-02931277v1

[hal-02978425] Le blaireau européen (Meles meles L.). Synthèse des connaissances européennes. Partie 1 : choix de l'habitat, structure et densité spatiale des terriers

The European badger (Meles meles L.) has a wide range in Europe and France; it is a social animal that generally lives in a group or family clan that are housed in setts. Although badgers sometimes settle in urban areas, environments chequered with oak trees and open areas (meadows, hedges, rangeland) are the generally preferred biotope. In these environments, they tend to dig their burrows in looser earth on moderate slopes close to the edge of the forest, but far from manmade infrastructures. The surface area of a sett va- ries from a few square meters (< 100 m2) to several hundred (> 500 m2). Typically, the number of entrances, the incremental length of the tunnels and the number of chambers increase with surface area. In smaller setts (< 100 m2; referred to as “secondary”), the number of entrances is generally less than 10 (often 4 to 6), the number of chambers is between 0 and 3 and the incremental length of the tunnels less than 70 m. For larger setts (at least 200 to 300 m2; referred to as “main setts”), there are between 10 and 15 entrances, and there are often more than 10 chambers and the incremental tunnel length exceeds 100 metres. In Europe, the average density of setts is 1.1 ± 1.9 per km2. The highest densities are in Western Europe (Ireland, United Kingdom, France, Spain, etc.) where the average values recorded are between 1.4 and 2.2 setts per km2. Observations further to the east (Central and Eastern Europe) find densities that are 10 times less, with often less than one sett per 10 km2.

ano.nymous@ccsd.cnrs.fr.invalid (François F. Lebourgeois) 26 Oct 2020

https://agroparistech.hal.science/hal-02978425v1

[hal-02610238] Stand growth and structure of mixed-species and monospecific stands of Scots pine (Pinus sylvestris L.) and oak (Q. robur L., Quercus petraea (Matt.) Liebl.) analysed along a productivity gradient through Europe

Past failures of monocultures, caused by wind-throw or insect damages, and ongoing climate change currently strongly stimulate research into mixed-species stands. So far, the focus has mainly been on combinations of species with obvious complementary functional traits. However, for any generalization, a broad overview of the mixing reactions of functionally different tree species in different mixing proportions, patterns and under different site conditions is needed, including assemblages of species with rather similar demands on resources such as light. Here, we studied the growth of Scots pine and oak in mixed versus monospecific stands on 36 triplets located along a productivity gradient across Europe, reaching from Sweden to Spain and from France to Georgia. The set-up represents a wide variation in precipitation (456-1250 mm year-1), mean annual temperature (6.7-11.5 °C) and drought index by de Martonne (21-63 mm °C-1). Stand inventories and increment cores of trees stemming from 40- to 132-year-old, fully stocked stands on 0.04-0.94-ha-sized plots provided insight into how species mixing modifies stand growth and structure compared with neighbouring monospecific stands. On average, the standing stem volume was 436 and 360 m3 ha-1 in the monocultures of Scots pine and oak, respectively, and 418 m3 ha-1 in the mixed stands. The corresponding periodical annual volume increment amounted to 10.5 and 9.1 m3 ha-1 year-1 in the monocultures and 10.5 m3 ha-1 year-1 in the mixed stands. Scots pine showed a 10% larger quadratic mean diameter (p is smaller than 0.05), a 7% larger dominant diameter (p is smaller than 0.01) and a 9% higher growth of basal area and volume in mixed stands compared with neighbouring monocultures. For Scots pine, the productivity advantages of growing in mixture increased with site index (p is smaller than 0.01) and water supply (p is smaller than 0.01), while for oak they decreased with site index (p is smaller than 0.01). In total, the superior productivity of mixed stands compared to monocultures increased with water supply (p is smaller than 0.10). Based on 7843 measured crowns, we found that in mixture both species, but especially oak, had significantly wider crowns (p is smaller than 0.001) than in monocultures. On average, we found relatively small effects of species mixing on stand growth and structure. Scots pine benefiting on rich, and oak on poor sites, allows for a mixture that is productive and most likely climate resistant all along a wide ecological gradient. We discuss the potential of this mixture in view of climate change.

ano.nymous@ccsd.cnrs.fr.invalid (Hans Pretzsch) 16 May 2020

https://hal.inrae.fr/hal-02610238v1

[hal-03365826] Assessing the dominant height of oriental beech (Fagus orientalis L.) in relation to edaphic and physiographic variables in the Hyrcanian Forests of Iran

Description of the subject. This study evaluates the application of Boosted Regression Trees (BRT) for predicting beech dominant height in the Hyrcanian forests of Iran, inscribed as a UNESCO’s World Heritage due to its remarkable biodiversity. Objectives. It is widely accepted that tree growth can be influenced by a wide variety of factors such as climate, topography, soil conditions and competition for resources. The early dominant height of trees modelling studies used the multiple linear regression. The development of more advanced non-parametric and machine learning methods provided opportunities to overcome the nonlinear relationships in forest ecosystems. Method. In this study, boosted regression trees was evaluated to model the dominant height of Fagus orientalis as the most important tree species in the Hyrcanian forest, Iran. Dominant height was related to soil and topographical variables, which are available for 190 sample plots covering all importance environmental gradients in the research area. Results. The results indicated BRT were found to outperform for modelling beech dominant height. This technique showed that phosphorus, percentage nitrogen, magnesium and percentage sand were among the most important variables. Conclusions. This study demonstrates the ability of BRT to accurately model the dominant height of oriental beech in relation to environmental predictors, and encourages its use in forest ecology.

ano.nymous@ccsd.cnrs.fr.invalid (Seyed Jalil Alavi) 05 Oct 2021

https://hal.inrae.fr/hal-03365826v1

[hal-03273208] La crise des scolytes (Ips typographus) ravageurs de l’Épicéa commun (Picea abies) vue de l’intérieur Retours sur une enquête qualitative auprès d’acteurs du nord-est de la France et sa zone transfrontalière (Allemagne, Belgique) réalisée fin 2019 – début 2020

L’épidémie de scolytes (essentiellement Ips typographus) qui sévit depuis 2018 dans les pessières d’Europe a conduit à une situation de crise dans la filière forêt-bois. Cette étude a pour objectif de caractériser et de comprendre la façon dont les acteurs font face à ces événements afin d’en tirer des enseignements pour de futures crises. Une enquête qualitative a été conduite entre novembre 2019 et janvier 2020 auprès de 41 acteurs de la filière forêt-bois dans les régions Grand Est, Bourgogne-Franche-Comté, Bade-Wurtemberg et Wallonie. Elle a mis en évidence des freins et points de blocage concernant la gestion de cette crise tels qu’un manque d’anticipation, des difficultés techniques et financières pour mener les actions opérationnelles nécessaires, une communication lente au niveau national, ou des difficultés administratives pour obtenir des aides financières. En revanche, la crise semble avoir conduit à un renforcement des collaborations au sein de la filière, notamment grâce au travail des structures interprofessionnelles.

ano.nymous@ccsd.cnrs.fr.invalid (Samuel Sénécal) 29 Jun 2021

https://agroparistech.hal.science/hal-03273208v1

[hal-03209287] Photoperiod and temperature as dominant environmental drivers triggering secondary growth resumption in Northern Hemisphere conifers

Wood formation consumes around 15% of the anthropogenic CO 2 emissions per year and plays a critical role in long-term sequestration of carbon on Earth. However, the exogenous factors driving wood formation onset and the underlying cellular mechanisms are still poorly understood and quantified, and this hampers an effective assessment of terrestrial forest productivity and carbon budget under global warming. Here, we used an extensive collection of unique datasets of weekly xylem tissue formation (wood formation) from 21 coniferous species across the Northern Hemisphere (latitudes 23 to 67°N) to present a quantitative demonstration that the onset of wood formation in Northern Hemisphere conifers is primarily driven by photoperiod and mean annual temperature (MAT), and only secondarily by spring forcing, winter chilling, and moisture availability. Photoperiod interacts with MAT and plays the dominant role in regulating the onset of secondary meristem growth, contrary to its as-yet-unquantified role in affecting the springtime phenology of primary meristems. The unique relationships between exogenous factors and wood formation could help to predict how forest ecosystems respond and adapt to climate warming and could provide a better understanding of the feedback occurring between vegetation and climate that is mediated by phenology. Our study quantifies the role of major environmental drivers for incorporation into state-of-the-art Earth system models (ESMs), thereby providing an improved assessment of long-term and high-resolution observations of biogeochemical cycles across terrestrial biomes.

ano.nymous@ccsd.cnrs.fr.invalid (Jian-Guo Huang) 27 Apr 2021

https://hal.inrae.fr/hal-03209287v1

[hal-03040768] Water potential control of turgor‐driven tracheid enlargement in Scots pine at its xeric distribution edge

The extent to which water availability can be used to predict the enlargement and final dimensions of xylem conduits remains an open issue. We reconstructed the time course of tracheid enlargement in Pinus sylvestris trees in central Spain by repeated measurements of tracheid diameter on microcores sampled weekly during a 2 yr period. We analyzed the role of water availability in these dynamics empirically through time-series correlation analysis and mechanistically by building a model that simulates daily tracheid enlargement rate and duration based on Lockhart's equation and water potential as the sole input. Tracheid enlargement followed a sigmoid-like time course, which varied intra- and interannually. Our empirical analysis showed that final tracheid diameter was strongly related to water availability during tracheid enlargement. The mechanistic model was calibrated and successfully validated (R-2 = 0.92) against the observed tracheid enlargement time course. The model was also able to reproduce the seasonal variations of tracheid enlargement rate, duration and final diameter (R-2 = 0.84-0.99). Our results support the hypothesis that tracheid enlargement and final dimensions can be modeled based on the direct effect of water potential on turgor-driven cell expansion. We argue that such a mechanism is consistent with other reported patterns of tracheid dimension variation.

ano.nymous@ccsd.cnrs.fr.invalid (Antoine Cabon) 04 Dec 2020

https://hal.inrae.fr/hal-03040768v1

[hal-03207504] Altered energy partitioning across terrestrial ecosystems in the European drought year 2018

Drought and heat events, such as the 2018 European drought, interact with the exchange of energy between the land surface and the atmosphere, potentially affecting albedo, sensible and latent heat fluxes, as well as CO 2 exchange. Each of these quantities may aggravate or mitigate the drought, heat, their side effects on productivity, water scarcity and global warming. We used measurements of 56 eddy covariance sites across Europe to examine the response of fluxes to extreme drought prevailing most of the year 2018 and how the response differed across various ecosystem types (forests, grasslands, croplands and peatlands). Each component of the surface radiation and energy balance observed in 2018 was compared to available data per site during a reference period 2004–2017. Based on anomalies in precipitation and reference evapotranspiration, we classified 46 sites as drought affected. These received on average 9% more solar radiation and released 32% more sensible heat to the atmosphere compared to the mean of the reference period. In general, drought decreased net CO 2 uptake by 17.8%, but did not significantly change net evapotranspiration. The response of these fluxes differed characteristically between ecosystems; in particular, the general increase in the evaporative index was strongest in peatlands and weakest in croplands. This article is part of the theme issue ‘Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale’.

ano.nymous@ccsd.cnrs.fr.invalid (Alexander Graf) 25 Apr 2021

https://hal.inrae.fr/hal-03207504v1

[hal-03043589] Contrasting Dependencies of Photosynthetic Capacity on Leaf Nitrogen in Early- and Late-Successional Tropical Montane Tree Species

Differences in photosynthetic capacity among tree species and tree functional types are currently assumed to be largely driven by variation in leaf nutrient content, particularly nitrogen (N). However, recent studies indicate that leaf N content is often a poor predictor of variation in photosynthetic capacity in tropical trees. In this study, we explored the relative importance of area-based total leaf N content (N tot) and within-leaf N allocation to photosynthetic capacity versus light-harvesting in controlling the variation in photosynthetic capacity (i.e. V cmax , J max) among mature trees of 12 species belonging to either early (ES) or late successional (LS) groups growing in a tropical montane rainforest in Rwanda, Central Africa. Photosynthetic capacity at a common leaf temperature of 25˚C (i.e. maximum rates of Rubisco carboxylation, V cmax25 and of electron transport, J max25) was higher in ES than in LS species (+ 58% and 68% for V cmax25 and J max25 , respectively). While N tot did not significantly differ between successional groups, the photosynthetic dependency on N tot was markedly different. In ES species, V cmax25 was strongly and positively related to N tot but this was not the case in LS species. However, there was no significant trade-off between relative leaf N investments in compounds maximizing photosynthetic capacity versus compounds maximizing light harvesting. Both leaf dark respiration at 25˚C (+ 33%) and, more surprisingly, apparent photosynthetic quantum yield (+ 35%) was higher in ES than in LS species. Moreover, R d25 was positively related to N tot for both ES and LS species. Our results imply that efforts to quantify carbon fluxes of tropical montane rainforests would be improved if they considered contrasting within-leaf N allocation and photosynthetic N tot dependencies between species with different successional strategies.

ano.nymous@ccsd.cnrs.fr.invalid (Camille Ziegler) 07 Dec 2020

https://hal.science/hal-03043589v1

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Productions 2020

HAL : Dernières publications

[hal-02434220] TRY plant trait database – enhanced coverage and open access

[hal-02650649] Long-term thermal sensitivity of Earth’s tropical forests

[hal-03778635] The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data

[hal-02995533] Ecosystem transpiration and evaporation: Insights from three water flux partitioning methods across FLUXNET sites

[hal-02957456] Non-stomatal processes reduce gross primary productivity in temperate forest ecosystems during severe edaphic drought

[hal-03040751] New developments in understanding plant water transport under drought stress

[hal-03038558] Dernières innovations sur la plantation forestière. Contribution de la R&D pour accompagner les évolutions attendues dans les pratiques

[hal-02927318] How does contemporary selection shape oak phenotypes?

[hal-02652095] Decreasing stand density favors resistance, resilience, and recovery of Quercus petraea trees to a severe drought, particularly on dry sites

[hal-03051411] Energy, water and carbon exchanges in managed forest ecosystems: description, sensitivity analysis and evaluation of the INRAE GO+ model, version 3.0

[hal-03179773] Temporal trends in tree defoliation and response to multiple biotic and abiotic stresses

[hal-02963149] Le profil cultural : une méthode d'observation pour analyser les impacts de la préparation mécanisée du site sur la structure du sol

[hal-02544340] Comment l'Office national des forêts anticipe les effets du changement climatique ?

[hal-03037487] Cultivation profile: a visual evaluation method of soil structure adapted to the analysis of the impacts of mechanical site preparation in forest plantations

[hal-02544285] La croissance des forêts et les changements environnementaux

[hal-03038406] How does oak mast seeding affect the feeding behavior of sympatric red and roe deer?

[hal-02870299] Which oak provenances for the 22nd century in Western Europe? Dendroclimatology in common gardens

[hal-03040730] In situ estimation of genetic variation of functional and ecological traits in Quercus petraea and Q. robur

[hal-03048253] Vegetation unit assignments: phytosociology experts and classification programs show similar performance but low convergence

[hal-03038588] Evaluation de l’intérêt d’une préparation mécanisée, résultats d’un essai de semis artificiel de Pin sylvestre dans les Vosges.

[hal-02989071] Gestion forestière intégrée des insectes ravageurs : exemple par l’étude de la niche écologique du hanneton forestier (Melolontha hippocastani Fabr. 1801)

[hal-03048264] EUNIS Habitat Classification: Expert system, characteristic species combinations and distribution maps of European habitats

[hal-03045938] Natura 2000 forest habitats: climatic debt in lowlands and thermophilization in highlands

[hal-02610246] Species mixing reduces drought susceptibility of Scots pine (Pinus sylvestris L.) and oak (Quercus robur L., Quercus petraea (Matt.) Liebl.) - Site water supply and fertility modify the mixing effect

[hal-02949790] A standard protocol for reporting species distribution models

[hal-03317972] Ancient forest statistics provide centennial perspective over the status and dynamics of forest area in France

[hal-02948750] Validation of Space-based albedo products from upscaled tower-based measurements over Heterogeneous and Homogeneous landscapes

[hal-02948747] Contrasting patterns of tree species mixture effects on wood δ13C along an environmental gradient

[hal-02934348] Sacrificing growth and maintaining a dynamic carbohydrate storage are key processes for promoting beech survival under prolonged drought conditions

[hal-02948828] Microgeographic local adaptation and ecotype distributions: The role of selective processes on early life‐history traits in sympatric, ecologically divergent Symphonia populations

[hal-02504844] Selective and taxon-dependent effects of semi-feral cattle grazing on tree regeneration in an old-growth Mediterranean mountain forest

[hal-03043585] Traits controlling shade tolerance in tropical montane trees

[hal-02975249] Early effects of temperate agroforestry practices on soil organic matter and microbial enzyme activity

[hal-02527995] Distribution of soil properties along forest-grassland interfaces: Influence of permanent environmental factors or land-use after-effects?

[hal-03209300] Reply to Elmendorf and Ettinger: Photoperiod plays a dominant and irreplaceable role in triggering secondary growth resumption

[hal-03085655] Unprecedented pluri-decennial increase in the growing stock of French forests is persistent and dominated by private broadleaved forests

[hal-02948752] Lack of effect of admixture proportion and tree density on water acquisition depth for European beech (Fagus sylvatica L.) and sycamore maple (Acer pseudoplatanus L.)

[hal-02549007] Limiting factors of aspen radial growth along a climatic and soil water budget gradient in south-western Siberia

[hal-03273202] Effet de la hauteur de prélèvement sur la composition quantitative et qualitative des polyphénols de l’écorce d’Abies alba Mill.

[hal-03046910] Do tree rings record changes in soil fertility? Results from a Quercus petraea fertilization trial

[hal-02942642] Sensitivity of gross primary productivity to climatic drivers during the summer drought of 2018 in Europe

[hal-02931277] A Machine-Learning Approach for Classifying Defects on Tree Trunks using Terrestrial LiDAR

[hal-02978425] Le blaireau européen (Meles meles L.). Synthèse des connaissances européennes. Partie 1 : choix de l'habitat, structure et densité spatiale des terriers

[hal-02610238] Stand growth and structure of mixed-species and monospecific stands of Scots pine (Pinus sylvestris L.) and oak (Q. robur L., Quercus petraea (Matt.) Liebl.) analysed along a productivity gradient through Europe

[hal-03365826] Assessing the dominant height of oriental beech (Fagus orientalis L.) in relation to edaphic and physiographic variables in the Hyrcanian Forests of Iran

[hal-03273208] La crise des scolytes (Ips typographus) ravageurs de l’Épicéa commun (Picea abies) vue de l’intérieur Retours sur une enquête qualitative auprès d’acteurs du nord-est de la France et sa zone transfrontalière (Allemagne, Belgique) réalisée fin 2019 – début 2020

[hal-03209287] Photoperiod and temperature as dominant environmental drivers triggering secondary growth resumption in Northern Hemisphere conifers

[hal-03040768] Water potential control of turgor‐driven tracheid enlargement in Scots pine at its xeric distribution edge

[hal-03207504] Altered energy partitioning across terrestrial ecosystems in the European drought year 2018

[hal-03043589] Contrasting Dependencies of Photosynthetic Capacity on Leaf Nitrogen in Early- and Late-Successional Tropical Montane Tree Species