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[hal-04174525] Masting is uncommon in trees that depend on mutualist dispersers in the context of global climate and fertility gradients
The benefits of masting (volatile, quasi-synchronous seed production at lagged intervals) include satiation of seed predators, but these benefits come with a cost to mutualist pollen and seed dispersers. If the evolution of masting represents a balance between these benefits and costs, we expect mast avoidance in species that are heavily reliant on mutualist dispersers. These effects play out in the context of variable climate and site fertility among species that vary widely in nutrient demand. Meta-analyses of published data have focused on variation at the population scale, thus omitting periodicity within trees and synchronicity between trees. From raw data on 12 million tree-years worldwide, we quantified three components of masting that have not previously been analysed together: (i) volatility, defined as the frequency-weighted year-to-year variation; (ii) periodicity, representing the lag between high-seed years; and (iii) synchronicity, indicating the tree-to-tree correlation. Results show that mast avoidance (low volatility and low synchronicity) by species dependent on mutualist dispersers explains more variation than any other effect. Nutrient-demanding species have low volatility, and species that are most common on nutrient-rich and warm/wet sites exhibit short periods. The prevalence of masting in cold/dry sites coincides with climatic conditions where dependence on vertebrate dispersers is less common than in the wet tropics. Mutualist dispersers neutralize the benefits of masting for predator satiation, further balancing the effects of climate, site fertility and nutrient demands.
ano.nymous@ccsd.cnrs.fr.invalid (Tong Qiu) 05 Jul 2024
https://hal.science/hal-04174525v1
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[hal-04133784] Thresholds for persistent leaf photochemical damage predict plant drought resilience in a tropical rainforest
Water stress can cause declines in plant function that persist after rehydration. Recent work has defined ‘resilience’ traits characterizing leaf resistance to persistent damage from drought, but whether these traits predict resilience in whole-plant function is unknown. It is also unknown whether the coordination between resilience and ‘resistance’ – the ability to maintain function during drought – observed globally occurs within ecosystems. For eight rainforest species, we dehydrated and subsequently rehydrated leaves, and measured water stress thresholds for declines in rehydration capacity and maximum quantum yield of photosystem II (Fv/Fm). We tested correlations with embolism resistance and dry season water potentials (ΨMD), and calculated safety margins for damage (ΨMD – thresholds) and tested correlations with drought resilience in sap flow and growth. Ψ thresholds for persistent declines in Fv/Fm, indicating resilience, were positively correlated with ΨMD and thresholds for leaf vein embolism. Safety margins for persistent declines in Fv/Fm, but not rehydration capacity, were positively correlated with drought resilience in sap flow. Correlations between resistance and resilience suggest that species' differences in performance during drought are perpetuated after drought, potentially accelerating shifts in forest composition. Resilience to photochemical damage emerged as a promising functional trait to characterize whole-plant drought resilience.
ano.nymous@ccsd.cnrs.fr.invalid (Claire Fortunel) 20 Jun 2023
https://hal.inrae.fr/hal-04133784v1
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[hal-04243684] Evaluation MultiCritère des Systèmes Agricoles et Alimentaires (EMC-SAgA) Bilan des activités et Poursuites envisagées
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ano.nymous@ccsd.cnrs.fr.invalid (Geneviève Gésan-Guiziou) 16 Oct 2023
https://hal.inrae.fr/hal-04243684v1
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[hal-03930047] Monitoring the risk of <i>Legionella</i> infection using a general Bayesian network updated from temporal measurements in agricultural irrigation with reclaimed wastewater
This paper presents a model for the risk assessment of pathogen inhalation from sprinkler irrigation using treated wastewater. Reuse of reclaimed wastewater for agricultural irrigation is an expanding practice worldwide. This practice needs to be monitored, partly because of pathogens that the water may contain after treatments. More particularly, sprinkler irrigation is known to generate aerosols which may lead to severe health risks to the population close to irrigated areas in case of the presence of Legionella bacteria in the water. A pilot experiment was conducted on two corn fields in South-Western France, irrigated with wastewater undergoing two different water treatments (ultra-filtration and UV). Water analyses have shown high levels of Legionella in the water even after a standard wastewater treatment plant (WWTP) cleaning process followed by the UV treatment (up to 106 GC per L in 2019). In this context, an updated general Bayesian network (GBN), using discrete and continuous random variables, in quantitative microbial risk assessment (QMRA) is proposed to monitor the risk of Legionella infection in the vicinity of the irrigated plots. The model's originality is based on i) a graphical probabilistic model that describes the exposure pathway of Legionella from the WWTP to the population using observed and non-observed variables and ii) the model inference updating at each new available measurement. Different scenarios are simulated according to the exposure time of the persons, taking into account various distances from the emission source and a large dataset of climatic data. From the learning process included in the Bayesian principle, quantities of interest (contaminations before and after water treatments, inhaled dose, probabilities of infection) can be quantified with their uncertainty before and after the inclusion of each new data collected in situ. This approach gives a rigorous tool that allows monitoring the risks, facilitates discussions with reuse experts and progressively reduces uncertainty quantification through field data accumulation. For the two pilot treatments analyzed in this study, the median annual risk of Legionella infection did not exceed the US EPA annual infection benchmark of 10−4 for any of the population at risk during the past few months of the pilot experiment (DALYs are estimated up to 10−5). The risk still bears watching with support from the method shown in this work.
ano.nymous@ccsd.cnrs.fr.invalid (Gaspar Massiot) 03 Dec 2024
https://hal.science/hal-03930047v2
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[hal-04001980] Ellenberg‐type indicator values for European vascular plant species
Aims: Ellenberg-type indicator values are expert-based rankings of plant species according to their ecological optima on main environmental gradients. Here we extend the indicator-value system proposed by Heinz Ellenberg and co-authors for Central Europe by incorporating other systems of Ellenberg-type indicator values (i.e., those using scales compatible with Ellenberg values) developed for other European regions. Our aim is to create a harmonized data set of Ellenberg-type indicator values applicable at the European scale.Methods: We collected European data sets of indicator values for vascular plants and selected 13 data sets that used the nine-, ten- or twelve-degree scales defined by Ellenberg for light, temperature, moisture, reaction, nutrients and salinity. We compared these values with the original Ellenberg values and used those that showed consistent trends in regression slope and coefficient of determination. We calculated the average value for each combination of species and indicator values from these data sets. Based on species' co-occurrences in European vegetation plots, we also calculated new values for species that were not assigned an indicator value.Results: We provide a new data set of Ellenberg-type indicator values for 8908 European vascular plant species (8168 for light, 7400 for temperature, 8030 for moisture, 7282 for reaction, 7193 for nutrients, and 7507 for salinity), of which 398 species have been newly assigned to at least one indicator value.Conclusions: The newly introduced indicator values are compatible with the original Ellenberg values. They can be used for large-scale studies of the European flora and vegetation or for gap-filling in regional data sets. The European indicator values and the original and taxonomically harmonized regional data sets of Ellenberg-type indicator values are available in the Supporting Information and the Zenodo repository.
ano.nymous@ccsd.cnrs.fr.invalid (Lubomír Tichý) 24 Feb 2023
https://u-picardie.hal.science/hal-04001980v1
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[hal-04047069] Large leaf hydraulic safety margins limit the risk of drought‐induced leaf hydraulic dysfunction in Neotropical rainforest canopy tree species
The sequence of key water potential thresholds from the onset of water stress to mortality, and the timing of stomatal closure with regard to leaf xylem embolism formation are essential to characterizing plant adaptive strategies to drought. This constitutes a critical knowledge gap for tropical rainforest species, which may be less vulnerable to drought than previously thought. We recorded key leaf and stem water potential thresholds, leaf hydraulic safety margins (HSMleaf), leaf stomatal safety margins (SSMleaf) and estimated native embolism levels during a normal-intensity dry season across 18 Neotropical rainforest tree species. We also solved a sequence of key water potential thresholds. Additionally, we provide a cross-biome analysis of SSMleaf encompassing 97 species from four major biomes based on a literature survey. In the studied rainforest species, leaf turgor loss point, used as a surrogate for stomatal closure, typically occurred before the onset of leaf xylem embolism. Most species exhibited positive HSMleaf and SSMleaf, with contrasting values across species and nearly absent embolism levels during the dry season irrespective of the experienced midday leaf water potentials. Our results point out that leaf xylem embolism is not routine for Neotropical rainforest tree species. Based on our proposal of the water potential sequence for tropical rainforest trees, we argue that leaf xylem embolism is a rare event for these species. This was supported by the literature survey, indicating that across biomes, most woody species have rather large SSMleaf and that leaves of tropical rainforest trees are not necessarily more vulnerable than in other biomes. However, we found evidence that some tropical rainforest species may be more vulnerable than others to ongoing climate change. Our data provide an opportunity to parametrize tree-based or land-surface models for tropical rainforests. Read the free Plain Language Summary for this article on the Journal blog.
ano.nymous@ccsd.cnrs.fr.invalid (Camille Ziegler) 02 Feb 2026
https://hal.inrae.fr/hal-04047069v1
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[hal-04593272] Sensitivity of South American tropical forests to an extreme climate anomaly
The tropical forest carbon sink is known to be drought sensitive, but it is unclear which forests are the most vulnerable to extreme events. Forests with hotter and drier baseline conditions may be protected by prior adaptation, or more vulnerable because they operate closer to physiological limits. Here we report that forests in drier South American climates experienced the greatest impacts of the 2015–2016 El Niño, indicating greater vulnerability to extreme temperatures and drought. The long-term, ground-measured tree-by-tree responses of 123 forest plots across tropical South America show that the biomass carbon sink ceased during the event with carbon balance becoming indistinguishable from zero (−0.02 ± 0.37 Mg C ha$^{−1}$ per year). However, intact tropical South American forests overall were no more sensitive to the extreme 2015–2016 El Niño than to previous less intense events, remaining a key defence against climate change as long as they are protected.
ano.nymous@ccsd.cnrs.fr.invalid (Amy Bennett) 04 Jun 2024
https://hal.science/hal-04593272v1
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[hal-04081509] Mapping territorial vulnerability to wildfires: A participative multi-criteria analysis
The Mediterranean region is routinely affected by forest fires, with adverse consequences on ecological, infrastructural, and socioeconomic assets. In a context of climate change, it is crucial for fire prevention and suppression to be able to identify locations where assets are most at risk, due to environmental, physical or socioeconomic reasons. Besides, this knowledge needs to be developed together with operational services and field experts to ensure their application. So far, fire risk research has largely focused on fire behavior, effects, and model simulation. In this article, we show how the concept of vulnerability can provide a flexible and relevant framework for assessing fire risk and be evaluated using a spatial multicriteria decision analysis method (MCDA)-the Analytical Hierarchy Process (AHP)-based on both quantitative data and expert judgment gathered through a participative approach. We focus on SouthEastern France, a region characterized by high economic and environmental stakes and heavily affected by wildfires. We develop a series of spatialized indicators using ecological, land-use and sociodemographic data which we aggregate to produce vulnerability maps for three categories of assets: population, ecosystems and infrastructures. An ex-post workshop was organized with field experts to put both the approach and results into discussion. Results reveal significant differences in indicators' perceived contributions to risk and vulnerability and enable appraising the contribution of sociodemographic factors, often overlooked in the literature. We also reveal differences in spatial patterns across both vulnerability subcomponents and exposed assets, helping identify primary and secondary vulnerability hotspots and underlying drivers. Consideration of multiple subcomponents of risk and vulnerability may help local decision makers prioritize how and where measures should be implemented, while the use of MCDA favors experience and knowledge sharing and among stakeholders while providing a basis of discussion.
ano.nymous@ccsd.cnrs.fr.invalid (Miguel Rivière) 26 Apr 2023
https://agroparistech.hal.science/hal-04081509v1
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[hal-04224631] Detection and attribution of an anomaly in terrestrial photosynthesis in Europe during the COVID-19 lockdown
Carbon dioxide (CO2) uptake by plant photosynthesis, referred to as gross primary production (GPP) at the ecosystem level, is sensitive to environmental factors, including pollutant exposure, pollutant uptake, and changes in the scattering of solar shortwave irradiance (SWin) − the energy source for photosynthesis. The spring lockdown due to COVID-19 resulted in improved air quality and atmospheric transparency, providing a unique opportunity to assess the impact of air pollutants on terrestrial ecosystem functioning. However, detecting these effects can be challenging as GPP is influenced by other meteorological drivers and management practices. Based on data collected from 44 European ecosystem-scale CO2 flux monitoring stations, we observed significant changes in spring GPP at 34 sites during 2020 compared to 2015-2019. Among these, 14 sites showed an increase in GPP associated with higher SW in , 10 sites had lower GPP linked to atmospheric and soil dryness, and seven sites were subjected to management practices. The remaining three sites exhibited varying dynamics, with one experiencing colder and rainier weather resulting in lower GPP, and two showing higher GPP associated with earlier spring melts. Analysis using the regional atmospheric chemical transport model (LOTOS-EUROS) indicated that the ozone (O3) concentration remained relatively unchanged at the research sites, making it unlikely that O3 exposure was the dominant factor driving the primary production anomaly. In contrast, SW in increased by 9.4 % at 36 sites, suggesting enhanced GPP possibly due to reduced aerosol optical depth and cloudiness. Our findings indicate that air pollution and cloudiness may weaken the terrestrial carbon sink by up to 16 %. Accurate and continuous ground-based observations are crucial for detecting and attributing subtle changes in terrestrial ecosystem functioning in response to environmental and anthropogenic drivers.
ano.nymous@ccsd.cnrs.fr.invalid (Angela Che Ing Tang) 02 Oct 2023
https://hal.inrae.fr/hal-04224631v1
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[hal-04681588] The TreeTrace Douglas database: quality assessment and traceability of Douglas fir
The objective of the present paper is to present an experimental dataset (downloadable at https:// doi. org/ 10. 15454/ YUNEGL) that can be of high value for the wood science community, and the first to be openly available to the best of author knowledge. The content of the database and detail about the data are presented in a datapaper [1]. The TreeTrace Douglas database includes images and measurements at several stages of the processing of Douglas fir logs, from sawmill logyard to machine grading and destructive testing of boards, and is suitable for research on quality assessment and traceability. A total of 52 long logs, 156 short logs, 208 wood discs and 346 boards was analysed. The image data includes RGB images of log ends and board ends, RGB images and CT slices of strips, a set of images of the boards (RGB, laser and X-rays) obtained with an industrial scanner dedicated to board grading.The measurements include wood density, growth ring widths, pith and board location in the logs, heartwood and sapwood areas, mechanical properties of each board obtained by vibratory and static testing, and visual grading of the boards. This database is suitable for working on the development of image processing algorithms to apply along the forest-wood chain: to trace the wood from the forest to the boards and to extract quality information at the different stages of the processing. A more traditional analysis of wood quality is also possible by relating the different variables (e.g., wood density and ring width) to each other, to their position in the tree, and by relating the quality measured on the logs to the boards that are extracted from them. This dataset can also directly be used for the development of strength grading algorithms since it includes all the measurement made by current board scanners and vibration testing devices, plus board traceability from the long log. Some examples of how the database can be used is described in the following part. Pith detection algorithms has been developed [2] because they often serve as a basis for the detection of other characteristics and because pith position provides information on the severity of the eccentricity potentially related to the presence of compression wood for softwood species. The data can also be used to analyse some wood quality characteristics of Douglas fir and to estimate the amount of information that can be recovered from the analysis of log ends. For instance, a study is underway to analyse the relationship between tree growth and wood density at the ring level from the database. Indeed, an automatic detection of ring widths associated with a ring width – ring density model would provide relevant quality information. It would also be possible to link the properties of the logs (ring widths, wood density, juvenile wood area, heartwood and sapwood amounts, pith eccentricity) to the mechanical performances of the boards obtained from these logs. Another possible application is the development of strength grading algorithms such as that of [3] and [4] since the dataset includes the main measurements made by current industrial board grading machines. The location of the boards in the logs can also be used in the models like that of [5].
ano.nymous@ccsd.cnrs.fr.invalid (Fleur Longuetaud) 30 Aug 2024
https://hal.science/hal-04681588v1
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[hal-04603883] Climate change and land use threaten global hotspots of phylogenetic endemism for trees
Across the globe, tree species are under high anthropogenic pressure. Risks of extinction are notably more severe for species with restricted ranges and distinct evolutionary histories. Here, we use a global dataset covering 41,835 species (65.1% of known tree species) to assess the spatial pattern of tree species’ phylogenetic endemism, its macroecological drivers, and how future pressures may affect the conservation status of the identified hotspots. We found that low-to-mid latitudes host most endemism hotspots, with current climate being the strongest driver, and climatic stability across thousands to millions of years back in time as a major co-determinant. These hotspots are mostly located outside of protected areas and face relatively high land-use change and future climate change pressure. Our study highlights the risk from climate change for tree diversity and the necessity to strengthen conservation and restoration actions in global hotspots of phylogenetic endemism for trees to avoid major future losses of tree diversity.
ano.nymous@ccsd.cnrs.fr.invalid (Wen-Yong Guo) 05 Jul 2024
https://hal.inrae.fr/hal-04603883v1
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[hal-04603888] Global beta-diversity of angiosperm trees is shaped by Quaternary climate change
As Earth’s climate has varied strongly through geological time, studying the impacts of past climate change on biodiversity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in biodiversity. Here, we assessed the influence of Quaternary climate change on spatial dissimilarity in taxonomic, phylogenetic, and functional composition among neighboring 200-kilometer cells (beta-diversity) for angiosperm trees worldwide. We found that larger glacial-interglacial temperature change was strongly associated with lower spatial turnover (species replacements) and higher nestedness (richness changes) components of beta-diversity across all three biodiversity facets. Moreover, phylogenetic and functional turnover was lower and nestedness higher than random expectations based on taxonomic beta-diversity in regions that experienced large temperature change, reflecting phylogenetically and functionally selective processes in species replacement, extinction, and colonization during glacial-interglacial oscillations. Our results suggest that future human-driven climate change could cause local homogenization and reduction in taxonomic, phylogenetic, and functional diversity of angiosperm trees worldwide.
ano.nymous@ccsd.cnrs.fr.invalid (Wu-Bing Xu) 09 Jan 2025
https://hal.inrae.fr/hal-04603888v1
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[hal-03872564] Species-mixing effects on crown dimensions and canopy packing in a young pine–birch plantation are modulated by stand density and irrigation
Mixed-species plantation forests are of high interest both because of their potentially superior productivity and multi-functionality benefits over monocultures. However, how trees of different species interact at the canopy level in mixed forests remains unclear, even at young growth stages. We tested whether crown shape and size and stand-level canopy packing were affected by stand composition and how mixture effects varied with stand density and irrigation. We measured crown attributes in pure and mixed plots of two light-demanding species, silver birch (Betula pendula Roth) and maritime pine (Pinus pinaster Ait.), in a 10-year-old tree diversity experiment (ORPHEE). This allowed us to estimate tree-level crown volumes and stand-level canopy packing. We found that (i) at the tree level, stand composition influenced crown-stem allometric relationships in pine but not in birch, (ii) mixture led to greater crown and tree dimensions in pine, but to the opposite for birch, (iii) the changes in crown volume resulted in a higher canopy packing in mixed stands, only at high density and with no irrigation, i.e., under highest constraints for light availability but also soil water availability, contrary to initial expectations. This study sheds light on the effects of water constraints on the aboveground mechanistic processes that explain greater productivity in young mixed plantations, and improves our understanding of canopy packing in mixed stands.
ano.nymous@ccsd.cnrs.fr.invalid (Soline Martin-Blangy) 13 Jan 2026
https://hal.inrae.fr/hal-03872564v1
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[hal-04169407] Functional trade‐offs are driven by coordinated changes among cell types in the wood of angiosperm trees from different climates
Wood performs several functions to ensure tree survival and carbon allocation to a finite stem volume leads to trade-offs among cell types. It is not known to what extent these trade-offs modify functional trade-offs and if they are consistent across climates and evolutionary lineages. Twelve wood traits were measured in stems and coarse roots across 60 adult angiosperm tree species from temperate, Mediterranean and tropical climates. Regardless of climate, clear trade-offs occurred among cellular fractions, but did not translate into specific functional trade-offs. Wood density was negatively related to hydraulic conductivity (Kth) in stems and roots, but was not linked to nonstructural carbohydrates (NSC), implying a functional trade-off between mechanical integrity and transport but not with storage. NSC storage capacity was positively associated with Kth in stems and negatively in roots, reflecting a potential role for NSC in the maintenance of hydraulic integrity in stems but not in roots. Results of phylogenetic analyses suggest that evolutionary histories cannot explain covariations among traits. Trade-offs occur among cellular fractions, without necessarily modifying trade-offs in function. However, functional trade-offs are driven by coordinated changes among xylem cell types depending on the dominant role of each cell type in stems and roots.
ano.nymous@ccsd.cnrs.fr.invalid (Guangqi Zhang) 06 Aug 2024
https://hal.inrae.fr/hal-04169407v1
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[hal-04216422] Détermination et cartographie de la vulnérabilité des essences au changement climatique récent.
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ano.nymous@ccsd.cnrs.fr.invalid (Christian C. Piedallu) 24 Sep 2023
https://hal.inrae.fr/hal-04216422v1
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[hal-04454254] Measuring photosynthesis of entire tree crowns and pulse label trees in large closed chamber with 13co2 in the field: Design and testing
Measuring the photosynthesis of entire tree crowns and pulse labelling trees with 13CO2 are valuable approaches to study carbon acquisition, transfer, and allocation; however, it is challenging for trees in the field. The objective was to develop and field test large chambers (35 - 45 m3) that enclosed the entire crown of a tree, provided a reliable estimate of tree crown photosynthesis, and ensured efficient 13CO2 labelling. The chambers, made of transparent polyethylene film pulled tightly over a frame, were equipped with an air conditioner, fans, and air blowers. Air temperature, relative humidity, and photosynthetic photon flux density were measured outside and inside each chamber. Six of 4-year-old rubber trees (Hevea brasiliensis) were pulsed-labelled with 18 L of 13CO2 in June and October 2016. The mean air temperature inside the chambers was 1.2 °C higher and the relative humidity 8 % lower than the outside air. The crown photosynthesis, calculated from the decrease in the CO2 concentration inside the chamber, was in the range 140 - 249 µmol s–1 and was significantly related to photosynthetic photon flux density, total leaf area of the tree, and average net CO2 assimilation at leaf level. The labelling efficiency, estimated as the ratio of the amount of 13C recovered in the foliage immediately after labelling divided by the amount of 13C delivered to the tree, was in the range 43 - 68 %. The designed chamber was suitable to estimate crown photosynthesis and perform 13CO2 pulse labelling of 5-m-tall trees in the field.
ano.nymous@ccsd.cnrs.fr.invalid (Ornuma Duangngam) 23 Jul 2025
https://hal.science/hal-04454254v1
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[hal-04207231] Genetic architecture of leaf specialized metabolites natural variation within sessile oak populations
Specialized or secondary metabolites (SMs) play a key role in plant resistance against abiotic stresses and defences against bioaggressors. For example, in sessile oaks Quercus petraea, phenolics contribute to reduce herbivore damage and improve drought resistance. In the context of global climate change the extensive diversity of compounds and variation of biosynthesis within species may play a key role to mitigate the increased frequency of stressful events such as drought, heat waves or emergent pathogens. Here, we study the genetic basis of leaf SMs natural variation in nine European provenances of sessile oaks and investigate signature of selections along the genome. We sampled mature leaves from high and low branches on 225 sessile oak trees located in a common garden and used untargeted metabolomics to characterise the variation of 219 leaf specialized metabolites. In addition, we used whole genome low-depth sequencing to genotype all individuals for 1.4M genetic markers. We then performed genome-wide association analyses, identified candidate genes underlying the variation of leaf SMs and compared signatures of selection at these genes to the rest of the genome. We found that leaf SMs displayed extensive within-provenance variation, but very little differentiation between provenances. For ∼10% of the metabolites we detected, most of this variation could be explained by a single genetic marker. Our results suggest that genetic variation of most leaf SMs is unlikely to be locally adaptive, and that varying selective pressures may act locally to maintain diversity at loci associated with leaf SM variation.
ano.nymous@ccsd.cnrs.fr.invalid (Domitille Coq--Etchegaray) 14 Sep 2023
https://hal.inrae.fr/hal-04207231v1
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[hal-04459758] Author Correction: Temperature extremes of 2022 reduced carbon uptake by forests in Europe
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ano.nymous@ccsd.cnrs.fr.invalid (Auke M van der Woude) 15 Feb 2024
https://hal.inrae.fr/hal-04459758v1
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[hal-04233219] Temperature extremes of 2022 reduced carbon uptake by forests in Europe
Abstract The year 2022 saw record breaking temperatures in Europe during both summer and fall. Similar to the recent 2018 drought, close to 30% (3.0 million km 2 ) of the European continent was under severe summer drought. In 2022, the drought was located in central and southeastern Europe, contrasting the Northern-centered 2018 drought. We show, using multiple sets of observations, a reduction of net biospheric carbon uptake in summer (56-62 TgC) over the drought area. Specific sites in France even showed a widespread summertime carbon release by forests, additional to wildfires. Partial compensation (32%) for the decreased carbon uptake due to drought was offered by a warm autumn with prolonged biospheric carbon uptake. The severity of this second drought event in 5 years suggests drought-induced reduced carbon uptake to no longer be exceptional, and important to factor into Europe’s developing plans for net-zero greenhouse gas emissions that rely on carbon uptake by forests.
ano.nymous@ccsd.cnrs.fr.invalid (Auke van der Woude) 31 Oct 2023
https://hal.inrae.fr/hal-04233219v1
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[hal-03689880] Drought tolerance traits in Neotropical trees correlate with the composition of phyllosphere fungal communities
Plant-associated microorganisms have shown to aid plants in coping with drought. However, the underlying mechanisms are poorly understood and there is uncertainty regarding which microbial taxa and functions are mostly involved. We explored these issues in Neotropical rainforests and identified foliar microorganisms that may play a role in drought tolerance of trees. Our objectives were to (1) test the relationship between drought tolerance traits in Neotropical trees and the diversity and composition of their foliar fungal and bacterial communities and (2) identify leaf microbial taxa positively or negatively associated with drought tolerance traits. Our results showed that the composition of leaf fungal communities, but not bacterial communities, was related to drought tolerance. We identified 27 fungal Amplicon Sequence Variants (ASVs) whose relative abundance co-varied with drought tolerance traits. Most variants were assigned to fungal clades often described as plant pathogens and increased in abundance with drought susceptibility. This greater relative abundance of leaf pathogens in the most drought-susceptible trees might increase their vulnerability to climate change. Moreover, we identified the Strelitziana and Ochroconis fungal genera as potential candidates for future culture-dependent studies aimed at understanding and improving drought tolerance in Neotropical forests.
ano.nymous@ccsd.cnrs.fr.invalid (Marine Cambon) 09 Jan 2025
https://hal.science/hal-03689880v1
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[hal-04172415] Dynamically simulating spruce budworm in eastern Canada and its interactions with wildfire
Eastern Spruce Budworm (ESBW) is a major agent of disturbance in Eastern Canada’s boreal forests. Outbreaks have historically led to widespread defoliation of its preferred host trees, fir and spruce species, leading to high rates of mortality. This in turn can result in significant economic losses and enhancement of fire potential in the region. Representation of such biotic disturbance has rarely been included in Dynamic Global Vegetation Models (DGVM), which have become essential tools in understanding and predicting forest dynamics in present and future contexts. We present novel representation of host-specific defoliation in a DGVM (LPJ-LMfire), to better represent disturbance regimes in the boreal forest of eastern Canada. Using host foliage density to trigger outbreak, we were able to calibrate and simulate general spatial patterns of defoliation relative to historical aerial sketch map data. Return intervals were thus sensitive to the growth rates of host trees. Modeled return intervals tended to be significantly longer than 30 years, the approximate observed return interval. A factorial experiment was performed on the interactions of ESBW with wildfire, which was found to be slightly enhanced in terms of burned areas after outbreaks due to increased fuel loads. Interactions between ESBW and fire were found to have higher interaction strength in the drier Western region of the boreal forest. Our study demonstrates that biotic disturbance and its interaction with wildfire can be effectively simulated in a DGVM. We show that bottom-up climatic controls are sufficient to drive simulated spatiotemporal patterns of ESBW that can be calibrated to generally match historical observations.
ano.nymous@ccsd.cnrs.fr.invalid (Hiromitsu Sato) 28 Jul 2023
https://hal.umontpellier.fr/hal-04172415v1
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[hal-04347203] Interactions within the climate-vegetation-fire nexus may transform 21st century boreal forests in northwestern Canada
Dry and warm conditions have exacerbated the occurrence of large and severe wildfires over the past decade in Canada's Northwest Territories (NT). Although temperatures are expected to increase during the 21st century, we lack understanding of how the climate-vegetation-fire nexus might respond. We used a dynamic global vegetation model to project annual burn rates, as well as tree species composition and biomass in the NT during the 21st century using the IPCC's climate scenarios. Burn rates will decrease in most of the NT by the mid-21st century, concomitant with biomass loss of fire-prone evergreen needleleaf tree species, and biomass increase of broadleaf tree species. The southeastern NT is projected to experience enhanced fire activity by the late 21st century according to scenario RCP4.5, supported by a higher production of flammable evergreen needleleaf biomass. The results underlie the potential for major impacts of climate change on the NT's terrestrial ecosystems.
ano.nymous@ccsd.cnrs.fr.invalid (Dorian M Gaboriau) 15 Dec 2023
https://hal.inrae.fr/hal-04347203v1
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[hal-04201566] Une vision pluridisciplinaire des sécheresses en forêt : comment les quantifier, évaluer leurs impacts et s'y adapter
Cet article propose une présentation structurée de travaux récents et en cours de quatre jeunes chercheuses sur le thème de la sécheresse édaphique en forêt en France métropolitaine, un phénomène qui devient de plus en plus fréquent et/ou intense perturbant le bon fonctionnement de ces écosystèmes. La gestion d'une crise sans précédent induite par des sécheresses récentes passe tout d'abord par la quantification et la cartographie de cet aléa, puis par l'évaluation et la compréhension des impacts induits par ce déficit hydrique sur la croissance primaire et secondaire des arbres. Enfin, diverses stratégies d'adaptation peuvent alors être mises en place afin de réduire la vulnérabilité des peuplements, en fonction des enjeux exposés (production de bois, séquestration de carbone) et de la gravité de ces impacts. Ces stratégies peuvent être ou non rentables pour le propriétaire forestier.
ano.nymous@ccsd.cnrs.fr.invalid (Clara Tallieu) 23 Jul 2025
https://hal.inrae.fr/hal-04201566v1
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[hal-04169477] Soil variation response is mediated by growth trajectories rather than functional traits in a widespread pioneer Neotropical tree
1. Trait-environment relationships have been described at the community level across tree species. However, whether interspecific trait-environment relationships are consistent at the intraspecific level is yet unknown. Moreover, we do not know how consistent is the response between organ vs. whole-tree level. 2. We examined phenotypic variability for 16 functional leaf (dimensions, nutrient, chlorophyll) and wood traits (density) across two soil types, Ferralitic Soil (FS) vs. White Sands (WS), on two sites for 70 adult trees of Cecropia obtusa Trécul (Urticaceae) in French Guiana. Cecropia is a widespread pioneer Neotropical genus that generally dominates early successional forest stages. To understand how soil types impact resource use through the processes of growth and branching, we examined the architectural development with a retrospective analysis of growth trajectories. We expect soil types to affect both, functional traits in relation to resource acquisition strategy as already described at the interspecific level, and growth strategies due to resource limitations with reduced growth on poor soils. 3. Functional traits were not involved in the soil response, as only two traits-leaf residual water content and K content-showed significant differences across soil types. Soil effects were stronger on growth trajectories, with WS trees having the slowest growth trajectories and less numerous branches across their lifespan. 4. The analysis of growth trajectories based on architectural analysis improved our ability to characterise the response of trees with soil types. The intraspecific variability is higher for growth trajectories than functional traits for C. obtusa, revealing the complementarity of the architectural approach with the functional approach to gain insights on the way trees manage their resources over their lifetime. Soil-related responses of Cecropia functional traits are not the same as those at the interspecific level, suggesting that the effects of the acting ecological processes are different between the two levels. Apart from soil differences, much variation was found across sites, which calls for further investigation of the factors shaping growth trajectories in tropical forests.
ano.nymous@ccsd.cnrs.fr.invalid (Sébastien Levionnois) 24 Jul 2023
https://hal.inrae.fr/hal-04169477v1
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[hal-04206530] Measuring uncertainty in ecosystem service correlations as a function of sample size
The ecosystem service literature has drastically expanded since the Millennium Ecosystem Assessment, yet the nature of how ecosystem services interact across space is still poorly understood. A key unresolved question is how efforts in sampling (a proxy for data availability) affect the calculation of the interactions or associations among ecosystem services. We contribute to answering this question by estimating a suite of ecosystem services and asking how the values of their interactions – in the form of spatial correlations – change as a function of the sampling rate of the landscape. Specifically, we estimate a set of seven ecosystem services for France (agricultural production potential, biodiversity, carbon storage, livestock grazing potential, net ecosystem productivity, pollination, and soil loss), applying four different measures for biodiversity, seven different methods for carbon storage, and three for pollination. We find that spatial correlations are fairly robust to the sampling rate, supporting the notion that moderate sampling rates across a heterogenous landscape are sufficient to obtain reliable estimates of the average correlation occurring across the landscape. In other words, despite heterogeneity in the spatial distribution of ecosystem services, at sufficient sample sizes we only need to randomly sample ten percent of the landscape to acquire an accurate measure of the correlations between all ecosystem services averaged across the entire landscape. Our results have implications for management, with applications for sampling extent and intensity and the identification of ecosystem service bundles.
ano.nymous@ccsd.cnrs.fr.invalid (David Shanafelt) 23 Jul 2025
https://hal.inrae.fr/hal-04206530v1
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[hal-03887107] Light U-Net with a New Morphological Attention Gate Model Application to Analyse Wood Sections
This article focuses on heartwood segmentation from cross-section RGB images (see Fig.1). In this context, we propose a novel attention gate (AG) model for both improving performance and making light convolutional neural networks (CNNs). Our proposed AG is based on mathematical morphology operators. Our light CNN is based on the U-Net architecture and called Light U-net (LU-Net). Experimental results show that AGs consistently improve the prediction performance of LU-Net across different wood cross-section datasets. Our proposed morphological AG achieves better performance than original U-Net with 10 times less parameters.
ano.nymous@ccsd.cnrs.fr.invalid (Rémi Decelle) 03 Mar 2023
https://hal.science/hal-03887107v1
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[hal-03987049] Traceability and quality assessment of Norway spruce (Picea abies (L.) H.Karst.) logs: the TreeTrace_spruce database
The TreeTrace_spruce database contains images and measurements of 100 Norway spruce (Picea abies (L.) H.Karst.) logs from Northeastern France, each about 4.5 m long. The image database includes RGB images of large and small ends of the logs and hyperspectral and computed tomography (CT) images of wood discs sampled at both log ends. The 100 logs were also fully X-ray scanned with a CT device for roundwoods and their top surface was scanned with a terrestrial LiDAR device. The measurements performed on discs include wood local density, growth ring widths and pith location. This database is complementary to another one (TreeTrace_Douglas) resulting from the same ANR project TreeTrace, but if the objectives are similar, the protocols and conditions of acquisition are not the same for these two databases. TreeTrace_spruce dataset is available at https://doi.org/10.57745/WKLTJI and associated metadata are available at https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/cffee2f1-18e1-4b53-9f5b-6cc4c66f1cb8.
ano.nymous@ccsd.cnrs.fr.invalid (Fleur Longuetaud) 19 Feb 2024
https://hal.science/hal-03987049v1
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[hal-04001076] Multi-elemental and Strontium-Neodymium Isotopic Signatures in Charred Wood: Potential for Wood Provenance Studies
The chemical composition of the wood reflects the composition of the soil over which the corresponding tree has developed. Multi-elemental and isotopic signatures, which are characteristic of the soil and underlying rock substrates, are potentially powerful tools for determining wood provenance. These tracers are of special interest for charred archaeological wood because they circumvent some limitations of dendrochronological provenancing linked to tree-ring loss. However, thermal degradation may introduce a significant bias in wood chemical and isotopic analyses. This experimental study focused on the effects of carbonization temperature on three geochemical wood markers: elemental signatures and isotopic signatures of strontium and neodymium (86Sr/87Sr and 143Nd/144Nd, respectively). Wood specimens from a variety of oak trees and stand locations were pyrolyzed at four temperatures (ranging from 200°C to 800°C) and analyzed using ICP-MS and µ-XRF (X-ray fluorescence) spectroscopy for elemental composition and with multiple collection ICP-MS (MC-ICP-MS) for strontium (Sr) and neodymium (Nd) isotope composition. The concentration of mineral nutrients generally increased with temperature, but the magnitude of the enrichment depended on the element, wood compartment (sapwood vs. heartwood), and geological substrate. The concentrations of rubidium, strontium, manganese, magnesium, potassium, and, to a lesser extent, calcium, were minimally affected by temperature, wood compartment, and substrate. The ratios between the concentrations of these elements, as well as the 86Sr/87Sr and 143Nd/144Nd isotope ratios, were stable over the entire temperature range. However, only 86Sr/87Sr and selected elemental ratios (calcium or magnesium normalized to manganese) were successful for site discrimination. Therefore, our multi-tracer approach provides promising new information to determine the provenance of charred archaeological wood
ano.nymous@ccsd.cnrs.fr.invalid (Anna Imbert Štulc) 22 Feb 2023
https://hal.science/hal-04001076v1
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[hal-03866312] How drought events during the last century have impacted biomass carbon in Amazonian rainforests
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ano.nymous@ccsd.cnrs.fr.invalid (Yitong Yao) 23 Nov 2022
https://hal.science/hal-03866312v1
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[hal-04181161] Pre- and post-drought conditions drive resilience of Pinus halepensis across its distribution range
Severe droughts limit tree growth and forest productivity worldwide, a phenomenon which is expected to aggravate over the next decades. However, how drought intensity and climatic conditions before and after drought events modulate tree growth resilience remains unclear, especially when considering the range-wide phenotypic variability of a tree species. We gathered 4632 Aleppo pine (Pinus halepensis Mill.) tree-ring width series from 281 sites located in 11 countries across the Mediterranean basin, representing the entire geographic and bioclimatic range of the species. For each site and year of the period 1950–2020, we quantified tree-growth resilience and its two components, resistance and recovery, to account for the impact of drought and the capacity to recover from it. Relative drought intensity of each year was assessed using SPEI (Standardized Precipitation Evapotranspiration Index), a climatic water deficit index. Generalized additive mixed models were used to explore the non-linear relationships between resilience and its two components and drought intensity, preceding and following years climatic conditions. We found that P. halepensis radial growth was highly dependent on the SPEI from September of the previous year to June of the current year. Trees growing under more arid bioclimates showed higher inter-annual growth variability and were more sensitive to drought, resulting in an increased response magnitude to pre-, during and post-drought conditions. In contrast to our expectations, drought intensity only slightly affected resilience, which was rather negatively affected by favorable preceding conditions and improved by favorable following conditions. Resilience and its components are highly dependent on preceding and following years climatic conditions, which should always be taken into account when studying growth response to drought. With the observed and predicted increase in drought frequency, duration and intensity, favorable conditions following drought episodes may become rare, thus threatening the future acclimation capacity of P. halepensis in its current distribution.
ano.nymous@ccsd.cnrs.fr.invalid (Léa Veuillen) 18 Aug 2023
https://amu.hal.science/hal-04181161v1
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[hal-04027770] Trade‐offs and synergies between ecosystem productivity and stability in temperate grasslands
Aim: It is crucial to monitor how the productivity of grasslands varies with its temporal stability for management of these ecosystems. However, identifying the direction of the productivity-stability relationship remains challenging because ecological stability has multiple components that can display neutral, positive or negative covariations. Furthermore, evidence suggests that the direction of the productivity-stability relationship depends on the biotic interactions and abiotic conditions that underlie ecosystem productivity and stability. We decipher the relationships between grassland productivity and two components of its stability in four habitat types with contrasting environments and flora.
ano.nymous@ccsd.cnrs.fr.invalid (Lucie Mahaut) 14 Mar 2023
https://hal.science/hal-04027770v1
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[hal-04262429] Extended duration of the budburst period under future climate warming: insights from a model
Spring phenology is a key indicator of the terrestrial ecosystems&#8217; response to climate change. However, most phenological studies only focus on the analysis of the average date of a particular phenological event in tree populations, and largely overlook the variability of this date within the populations, resulting in large uncertainties in projecting phenological change and the stability of community under ongoing climate warming. Here, we constructed a model able to simulate the within-population variability (WPV) of budburst dates in tree populations using budburst data observed from 2000 to 2021, and we used the model to evaluate the response of WPV to climate warming in five temperate deciduous tree species (Carpinus betulus, Quercus petraea, Fraxinus excelsior, Fagus sylvatica and Castanea sativa). The WPV model received support for all five species, with a RMSE of 8.6&#160;&#177;&#160;2.9 days over validation data, which is near the observation resolution. Retrospective simulations using past climate suggested that the beginning (i.e., date at which 20&#160;% trees burst their buds, BP20) and end (i.e., date at which 80&#160;% trees burst their buds, BP80) of budburst in the population advanced over 1961-2021 of 1.3 &#177; 0.4 days decade-1 and 1.4&#160;&#177;&#160;0.4 days decade -1, as a consequence of climate warming. However, the duration of the budburst period (DurBB, time interval between BP20 and BP80) did not change significantly. Using three climate models, we found BP20 and BP80 to occur later by 3.1 &#177; 1.3 days decade-1 and 3.8 &#177; 1.5 days decade-1 in populations of Quercus, Fraxinus and Carpinus along the 21st century, which was caused by insufficient chilling accumulation, contrasting with a continuous trend towards earlier budburst by 0.9 &#177;&#160;0.6 days decade-1 and 0.5 &#177; 0.7 days decade-1 in Fagus and Castanea. Importantly, the duration of the budburst period (DurBB) in the population was projected to increase in the future, especially for Quercus and Fraxinus, due to a stronger temperature sensitivity of the end of budburst in the population. Furthermore, our model suggests modifications at the community scale, with shifts in the budburst sequence for some species. Our work provides a novel model, simulating the continuity of budburst in tree populations in spring. This phenological model can be adapted to the study of other stages of the tree phenological cycle, which are all of continuous nature in tree populations (e.g., leaf senescence, wood formation etc.). Furthermore, based on this approach, our study projects a delayed, and extended duration of budburst in the population under climate warming for two out of the five species investigated. If confirmed in natura, these differential changes in budburst duration could influence the competition among species in forest communities.
ano.nymous@ccsd.cnrs.fr.invalid (Jianhong Lin) 27 Oct 2023
https://hal.science/hal-04262429v1
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[hal-04400731] An experimental test of the range-limiting drivers of Cedrus libani suggests an unexpectedly wide altitudinal range and a likely high resilience to future climate warming
Understanding the range-limiting drivers of species is essential to predict the distributional changes that are expected to result from climate warming. However, despite sustained theoretical interest and recent observational or experimental works, the ecological constraints that impose species’ range boundaries remain poorly understood. In this work, we seek to assess whether the range limits of the Cedar of Lebanon in natural conditions coincide with the limits of its climatic niche by comparing key fitness parameters of the species within and outside its altitudinal range and by investigating the ecological causes of the Cedar's disappearance outside its limits. We recorded the presence/absence of Cedar in 1241 plots along a 2800 m altitudinal gradient encompassing the Cedar natural range in Lebanon to assess its altitudinal range. We established in this region a set-up of 8 experimental sites spread over 2200 m of elevation, in order to extend it far beyond the altitudinal warm and cold limits of the Cedar's natural distribution. The constraints conditioning the climatic limits of the Cedar were investigated by establishing different watering modalities and by comparing Cedar performances with that of 3 competitor tree species. We measured the growth and survival at 3 years of the 1360 cedars planted in the set-up and those of competitor species. The experimental set-up revealed optimal survival and growth rates of the Cedar over an altitude range of 1500 m, three times higher than the altitudinal range of its natural distribution in Lebanon, which extends from 1300 to 1830 m altitude. Water stress limits the survival of the Cedar below 500 m, at an altitude much lower than its low altitudinal limit. Competition explains the absence of Cedar below 900 m altitude due to a superior growth of competitor species. Three thousand years of intensive exploitation of Cedar likely explain its absence between 900 and 1300 m altitude. Finally, cold temperature and water stress limit the survival of Cedar above 2000 m, an altitude slightly above the species cold limit under natural conditions. The high survival rate experimentally observed below the warm limit of the Cedar natural distribution gives hope for its resilience to future climate warming within its current range. If the pattern observed for the Cedar is common to many mountainous species, it would challenge predictions of extinction of these species under climate change and pave the way for adaptive actions, such as competition management, to improve their long-term survival.
ano.nymous@ccsd.cnrs.fr.invalid (Yaacoub Nassif) 17 Jan 2024
https://hal.science/hal-04400731v1
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[hal-04399987] L'impact du réchauffement climatique sur le cèdre du Liban pourrait être plus réduit qu'attendu
Dans un contexte de forte vulnérabilité du cèdre du Liban liée à des pressions anthropiques historiques et aux risques engendrés par le réchauffement climatique, nous avons comparé sa niche climatique en conditions naturelles avec celle obtenue par des tests de survie et de croissance établis le long d’un gradient altitudinal en conditions hydriques et de compétition contrôlées. Nous avons relevé la présence du cèdre dans 1241 placettes situées dans son aire naturelle au Liban pour préciser sa gamme altitudinale dans la nature. Nous avons ensuite établi dans cette région un dispositif de 8 sites expérimentaux répartis sur 2200 m de dénivelée de manière à l’étendre largement au-delà des extrêmes chauds et froids de la distribution naturelle du cèdre. Les contraintes conditionnant les limites climatiques du cèdre ont été recherchées en établissant différentes modalités d’arrosage et en plantant également 3 des principales espèces forestières méditerranéennes de la région sur chaque site expérimental. Nous avons mesuré la croissance et la survie à 3 ans des 1360 cèdres plantés dans le dispositif ainsi que celles des espèces compétitrices. Le dispositif expérimental a révélé un taux de survie et de croissance optimums du cèdre sur une gamme d’altitude de 1500 mètre de dénivelée, trois fois supérieure à la gamme altitudinale de sa distribution naturelle au Liban qui s’étend de 1300 à 1830m d’altitude. A moins de 500 m d’altitude, le stress hydrique limite la survie du cèdre à des altitudes très inférieures à sa limite naturelle basse. La compétition explique l’absence du cèdre sous 900m d’altitude du fait d’une croissance supérieure des espèces compétitrices. Trois mille ans d’exploitation intensive du cèdre pourraient expliquer son absence entre 900 et 1300m d’altitude. Enfin, le froid et le stress hydrique limitent la survie du cèdre au-delà de 2000 m, altitude légèrement supérieure à la limite froide de l’espèce dans les conditions naturelles. Le taux de survie élevé observé expérimentalement sous la limite chaude de la distribution naturelle du cèdre du Liban laisse espérer sa résistance face au réchauffement climatique futur dans son aire de répartition actuelle. Si le schéma observé chez le cèdre était commun à de nombreuses espèces montagnardes, cela remettrait en cause les prévisions d'extinction de ces espèces avec le changement climatique et ouvrirait la voie à des actions d'adaptation, telles que la gestion de la compétition, pour améliorer leur survie.
ano.nymous@ccsd.cnrs.fr.invalid (Yaacoub Nassif) 17 Jan 2024
https://hal.science/hal-04399987v1
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[hal-04294652] A model of the within-population variability of budburst in forest trees
Spring phenology is a key indicator of temperate and boreal ecosystems’ response to climate change. To date, most phenological studies have analyzed the mean date of budburst in tree populations while overlooking the large variability of budburst among individual trees. The consequences of neglecting the within-population variability (WPV) of budburst when projecting the dynamics of tree communities are unknown. Here, we develop the first model designed to simulate the WPV of budburst in tree populations. We calibrated and evaluated the model on 48,442 budburst observations collected between 2000 and 2022 in three major temperate deciduous trees, namely, hornbeam (Carpinus betulus), oak (Quercus petraea) and chestnut (Castanea sativa). The WPV model received support for all three species, with a root mean square error of 5.6 ± 0.3 days. Retrospective simulations over 1961–2022 indicated earlier budburst as a consequence of ongoing climate warming. However, simulations revealed no significant change for the duration of budburst (DurBB, i.e., the time interval from BP20 to BP80, which respectively represent the date when 20 % and 80 % of trees in a population have reached budburst), due to a lack of significant temperature increase during DurBB in the past. This work can serve as a basis for the development of models targeting intra-population variability of other functional traits, which is of increasing interest in the context of climate change.
ano.nymous@ccsd.cnrs.fr.invalid (Jianhong Lin) 20 Nov 2023
https://hal.science/hal-04294652v1
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[hal-05248503] Between and within species diversity of water use efficiency for Q. petraea and Q. robur : At the crossroad of ecology, ecophysiology and genetics
Climate change predictions tend towards drier summers, challenging forest management to maintain biomass production and survival while reducing water use. Sustainable forest management practices need to take into account these future environmental conditions. In this respect, genetic variation for water use efficiency (WUE), the ratio between biomass production and water use, could be mobilized for adapting forests to these future climates. A strong within species adaptive diversity of WUE related to soil water conditions would support an assisted migration forest management strategy. Here, the case of the two predominant European species Quercus robur and Q. petraea will be explored. A strong genetic control of WUE had already been shown for one Q. robur family. Here, the study of the genetic architecture of WUE was enlarged to Q. petraea and hybrid families, to establish the across species the genetic basis of WUE. To further clarify the functional basis of the difference in WUE and underlying traits, within and between both species, detailed ecophysiological measurements were carried out. These ecophysiological studies were complemented by gene expression studies in leaves and in guard cells. These indicated a within species variation of the molecular response to drought stress1. Finally, an existing common garden of Q. petraea allowed to characterise within and among population diversity in WUE2 Significant differences in WUE were found among populations but a much larger variability was observed within than among populations. The population plasticity of WUE to severe drought could be related to the soil type of the provenance sites, suggesting a local adaptation in terms of drought response strategies. The genotyping of these populations allowed to detect strong associations between WUE and its plasticity and sequenced genes. An overview will be given on this research strategy, ranging from detailed ecophysiology and gene expression to functional ecology and genomics. References 1 Le Provost G, Gerardin T, Plomion C, Brendel O (2022) Molecular plasticity to soil water deficit differs between sessile oak (Quercus Petraea (Matt.) Liebl.) high- and low-water use efficiency genotypes. Tree Physiology:tpac087. 2 Rabarijaona A, Ponton S, Bert D, Ducousso A, Richard B, Levillain J, Brendel O (2022) Provenance Differences in Water-Use Efficiency Among Sessile Oak Populations Grown in a Mesic Common Garden. Front For Glob Change 5:914199.
ano.nymous@ccsd.cnrs.fr.invalid (Oliver Brendel) 10 Sep 2025
https://hal.inrae.fr/hal-05248503v1
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[hal-04225453] ForEM : Forêt Et Modélisation. Un Réseau d’animation des chercheurs et développeurs francophones impliqués dans la modélisation des systèmes FORET -BOIS dans leurs environnements
La modélisation des systèmes FORÊT-BOIS implique des approches multiples et complémentaires autour de la dynamique forestière et des facteurs génétiques, environnementaux et sylvicoles qui la contrôlent, en interaction avec la sphère socioéconomique : filière forêt-bois, services écosystémiques, gestion des risques, territoires. Objectif : Forêt Et Modélisation : L'objectif du réseau ForEM est de créer des opportunités de rencontres et d'échanges et d'être un outil d'animation scientifique inter-organismes et pluridisciplinaire.
ano.nymous@ccsd.cnrs.fr.invalid (François de Coligny) 02 Oct 2023
https://hal.inrae.fr/hal-04225453v1
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[hal-04093388] Soil organic carbon models need independent time-series validation for reliable prediction
Abstract Numerical models are crucial to understand and/or predict past and future soil organic carbon dynamics. For those models aiming at prediction, validation is a critical step to gain confidence in projections. With a comprehensive review of ~250 models, we assess how models are validated depending on their objectives and features, discuss how validation of predictive models can be improved. We find a critical lack of independent validation using observed time series. Conducting such validations should be a priority to improve the model reliability. Approximately 60% of the models we analysed are not designed for predictions, but rather for conceptual understanding of soil processes. These models provide important insights by identifying key processes and alternative formalisms that can be relevant for predictive models. We argue that combining independent validation based on observed time series and improved information flow between predictive and conceptual models will increase reliability in predictions.
ano.nymous@ccsd.cnrs.fr.invalid (Julia Le Noë) 10 May 2023
https://hal.science/hal-04093388v1
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[mnhn-04273553] Multi-tracer approach to study the provenance of the charred medieval timbers of the framework of Notre-Dame de Paris
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ano.nymous@ccsd.cnrs.fr.invalid (Anna Imbert Štulc) 07 Nov 2023
https://mnhn.hal.science/mnhn-04273553v1
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[hal-05189724] The early growth response of a root facing an obstacle
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ano.nymous@ccsd.cnrs.fr.invalid (Manon Quiros) 28 Jul 2025
https://hal.inrae.fr/hal-05189724v1
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[hal-04300896] Mesurer le potentiel spontané électrique en milieu forestier pour observer les échanges hydriques dans le continuum subsurface-végétation-atmosphère
Les mesures de potentiel spontané électrique sont influencées par la variation des flux hydriques circulant dans le sol et au sein des arbres. Nous étudions ici comment ces données acquises en milieu forestier sont sensibles aux différents processus de transferts hydriques qui ont lieu dans le continuum subsurface-végétation-atmosphère. Pour cela, nous avons conçu et installé une expérience de mesures de potentiel spontané sur le tronc et au pied de plusieurs arbres d'une même parcelle forestière et complété ces mesures par des observations des variables environnementales.
ano.nymous@ccsd.cnrs.fr.invalid (Nolwenn Lesparre) 01 Dec 2023
https://hal.science/hal-04300896v1
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[hal-04533864] Genotypic differences in systemic root responses to mechanical obstacles
Abstract As roots grow through the soil to forage for water and nutrients, they encounter mechanical obstacles such as patches of dense soil and stones that locally impede root growth. Here, we investigated hitherto poorly understood systemic responses of roots to localised root impedance. Seedlings of two wheat genotypes were grown in hydroponics and exposed to impenetrable obstacles constraining the vertical growth of the primary or a single seminal root. We deployed high‐resolution in vivo imaging to quantify temporal dynamics of root elongation rate, helical root movement, and root growth direction. The two genotypes exhibited distinctly different patterns of systemic responses to localised root impedance, suggesting different strategies to cope with obstacles, namely stress avoidance and stress tolerance. Shallower growth of unconstrained seminal roots and more pronounced helical movement of unconstrained primary and seminal roots upon localised root impedance characterised the avoidance strategy shown by one genotype. Stress tolerance to localised root impedance, as exhibited by the other genotype, was indicated by relatively fast elongation of primary roots and steeper seminal root growth. These different strategies highlight that the effects of mechanical obstacles on spatiotemporal root growth patterns can differ within species, which may have major implications for resource acquisition and whole‐plant growth.
ano.nymous@ccsd.cnrs.fr.invalid (Tino Colombi) 05 Apr 2024
https://hal.inrae.fr/hal-04533864v1
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[hal-04188106] Biology and ecology of Pontederia crassipes in a Mediterranean river in Lebanon
Invasive aquatic plants are considered the second cause of biodiversity loss in aquatic ecosystems. Pontederia crassipes Mart., formerly Eichhornia crassipes (Mart.) Solms (water hyacinth) is one of the most dangerous invasive species in the world. Since 2006, P. crassipes has invaded Lebanon's Al Kabir River, causing ecological and socioeconomic problems. To solve them, ecological and biological characteristics are important to understand the water hyacinth response to variations in environmental conditions. The aims of this study were (i) to analyze P. crassipes growth and (ii) physico-chemical parameters at two sites and (iii) to determine ecological relationships between P. crassipes and other plant species. The main results show the existence of different cohorts of water hyacinth at the two sites. Differences in growth between these cohorts are likely due to physico-chemical differences. In addition, P. crassipes coexist with other invasive and native plants. This ecological study can help ecologists and stakeholders map invasive plants in rivers and improve their control
ano.nymous@ccsd.cnrs.fr.invalid (Youssra Ghoussein) 19 Jun 2025
https://institut-agro-rennes-angers.hal.science/hal-04188106v1
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[hal-04028874] Within and between population phenotypic variation in growth vigor and sensitivity to drought stress in five temperate tree species
Within-population variation in individual tree growth and response to climate has an impact on forest dynamics, resilience and adaptation to environmental change. Combining dendrochronological analyses with a process-based ecophysiological model simulating drought stress at the stand scale, we studied the phenotypic variation of two growth-related traits within 22 pure stands of five contrasted tree species sampled in the RENECOFOR network over a wide range of ecological conditions. First, we computed the annual stress level from soil, climate and stand inventory data. Second, we computed individual sensitivity as the quantitative growth response to drought stress level and individual vigor as the capacity to grow in favorable years relative to an average stand-level growth model. We analyzed within-population variation and covariation of individual vigor and sensitivity, their temporal changes during stand development, as well as the effect of environmental conditions on population-level means, variances and correlation. Our results show that within-population variances in sensitivity and vigor exceed the between-population variances for all species. The populations located in more stressful environments, i.e., low summer precipitation and extractable soil water, showed lower mean and variance of sensitivity, suggesting possible multiscale adaptation at the population level and within populations. None of the environmental factors considered had an effect on the average population vigor or on the within-population variance of vigor. We found a general positive correlation between individual growth sensitivity and vigor in 17 out of 22 populations, potentially revealing a growth performance trade-off. The correlation was more pronounced in low extractable soil water environments, which may be related to a need for stressful conditions to reveal the trade-off or be the consequence of adaptive processes, i.e., acclimation and selection. If high within-population stand phenotypic variation in growth traits contributes to the resilience and adaptive capacity of forests to climate change, a trade-off could represent a constraint on selection. We provide genetic and environmental arguments supporting the hypothesis of a trade-off, then we highlight the importance of integrating it into the management process, especially during selective thinning, to avoid indirectly increasing population sensitivity by selecting the most vigorous trees.
ano.nymous@ccsd.cnrs.fr.invalid (Victor Fririon) 20 Mar 2023
https://hal.inrae.fr/hal-04028874v1
