This session addresses the role of plant traits, biodiversity, acclimation, and adaptation in regulating the biogeochemical cycles of water, carbon, nitrogen, phosphorus, and sulphur across scales. We welcome conceptual, observational, experimental, and modelling studies from local to global levels, including in situ and remote sensing approaches.
Merging with original session 3.24 "Unlocking fruit crop resilience to a changing climate through stable isotopes and plant phenotyping integration”, this year's focus highlights agroecosystems and perennial fruit crops increasingly subjected to climate-induced stressors such as drought, salinity, and temperature extremes, including studies that integrate plant traits with stable isotope analyses (δ¹³C, δ¹⁵N, δ²H, δ¹⁸O, δ³⁴S) and plant phenomics (e.g., RGB, infrared, chlorophyll fluorescence, hyperspectral sensing) to explore physiological plasticity, resource-use efficiency, and adaptive responses. Special focus is given to multi-scalar approaches that connect soil–plant–atmosphere interactions, genotype-specific resilience, and pedoclimatic influences on plant metabolism. By combining biogeochemistry, eco-physiology, and agronomy, this session seeks to advance trait-based understanding of plant responses to global change and to promote climate-resilient agricultural systems.
Orals: Mon, 4 May, 14:00–17:55 | Room 1.85/86
Despite the critical role of stomata in regulating plant water use (transpiration) and carbon uptake (assimilation) during diurnal fluctuations, current land surface models rely on plant functional type-specific parameterization of stomatal conductance (gsw) that often struggles to reproduce observed stomatal dynamics. In particular, most established models ignore potential feedback between stomatal conductance and the within-canopy air space: an increase in gsw humidifies and cools the air surrounding the leaf, and decreases the vapor pressure deficit of the leaf (VPDleaf), which can further increase gsw. This creates a positive feedback loop that complicates distinguishing whether stomatal dynamics are a simple response to environmental variations (e.g. VPDair or light intensity) or a result of stomatal optimization in the presence of leaf-air feedback. A thorough understanding of these processes is crucial for modeling water and carbon fluxes under changing environmental conditions.
We measured continuous in situ gas exchange from individual leaves of wheat (Triticum aestivum) during multiple diurnal cycles under natural fluctuations of VPDleaf and light intensity driven by cloud cover. By adjusting chamber air exchange rate, we manipulated the strength of the experimental leaf-airfeedback, given that a low exchange rate makes the air inside the measurement cuvette more sensitive to leaf heat and gas exchange. Diurnal variations in gsw spanned an order of magnitude multiple times during the day, demonstrating the responsiveness of gsw to fluctuating environmental conditions and feedback strengths.
The stomatal optimality principle of Cowan and Farquhar (1977) predicts that gsw adjusts dynamically to environmental conditions to maximize the time-integral of carbon gain under constrained water availability by maintaining a constant marginal water cost (∂E) per carbon uptake (∂A) (λ = ∂E/∂A). According to the theory, the operational slope λ is constant among leaves of the same plant and responds only to soil moisture (θ). By measuring E and A simultaneously and calculating λ at stable light conditions (≥ 5 min), we test, in both laboratory and field studies, whether the operational slope λ converges to a similar value among leaves of the same plants, remains constant throughout a day and declines with reduced θ.
If λ proves to be stable between leaves of the same plant while responding to θ, an empirical relation between λ and θ within the root zone could serve as a powerful trait for predicting stomatal dynamics in wheat plants. It remains to be assessed how λ(θ), and therefore optimality principles, vary among cultivars and generations, whether it is equally useful for other species, and whether it is conserved under environmental change. The new method of measuring leaf-scale λ presented here opens the path to such studies.
How to cite: Seeburger, P. and Schymanski, S. J.: Are diurnal stomatal dynamics governed by Cowan-Farquhar optimality principles?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9593, https://doi.org/10.5194/egusphere-egu26-9593, 2026.
A mathematical framework is developed to quantify the stability of phloem transport and delineate “safe operating” regimes using bifurcation analysis. Sucrose production is linked to leaf photosynthesis using stomatal optimality, while sucrose translocation follows pressure-driven flow based on the Munch mechanism. The model couples xylem water potential, osmotic driving force, hydraulic resistance (using a sucrose-dependent viscosity), and distributed sink removal along the transport pathway. Systematic variation of key carbon transport controls, such as xylem water potential and sink strength, reveals multiple equilibria and stability boundaries beyond which phloem transport becomes unstable to small carbon loading fluctuations. Phloem failure emerges through a saddle-node bifurcation, yielding two stable sucrose loading states separated by an unstable branch where the lower equilibrium falls within reported sucrose loading ranges. The resulting stability maps provide a mechanistic basis for phloem vulnerability and suggest that vascular safety requires coordination between photosynthetic supply (e.g., $V_{c,max}$), pathway length, and transport capacity as water potential declines. This stability map provides a mechanistic constraint that can inform trait-based ecosystem modeling and provide hypotheses about acclimation and vulnerability across environments.
How to cite: Nakad, M., Youssef, L., Domec, J.-C., Sevanto, S., and Katul, G.: Safe Operating Regimes for Phloem Carbon Transport: A Bifurcation Framework, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8162, https://doi.org/10.5194/egusphere-egu26-8162, 2026.
Leaf traits collectively offer valuable insight into a plant’s photosynthetic strategy under varying environmental conditions. Eco-evolutionary optimality (EEO) theory can be used to predict photosynthetic trait variation, offering insight into the underlying mechanisms beyond what can be gleaned from data alone. EEO has been used to explore mechanisms underlying the variation in individual photosynthetic traits across space and time. Here, I extend this approach to (1) examine global variability in biochemical, stomatal, chemical, and morphological traits that collectively define an optimal photosynthetic strategy and (2) within-site variability in optimal photosynthetic strategies across different ecosystems. The global analysis revealed that the primary axis of variation was defined by differences in C3 and C4 plants with C4 plants displaying greater optimal intrinsic water use efficiency and higher amounts of photosynthetic nitrogen that generally conveyed faster rates of photosynthesis. This reflects the unique, fast-efficient strategy employed by C4 plants. The secondary axis of variation was defined by a correlation between optimal photosynthetic nitrogen use efficiency and optimal stomatal conductance. This was common across all plant types, with increasing aridity driving lower optimal stomatal conductance and nitrogen use efficiency, following expectations from photosynthetic least-cost theory. At the site-level, I generally found greater within-site than across-site variability in optimal photosynthetic strategy, suggesting a wide range of successful strategies within sites. The major site separator was between C4 grasslands and C3-dominated ecosystems, primarily because of greater water use efficiency and photosynthetic nitrogen investment at C4 sites. The results indicate that EEO theory can reproduce patterns of photosynthetic strategies across global gradients, while also revealing new insights into the clustering of these strategies. These results can be used to better understand photosynthetic trait data and, ultimately, plant physiological functioning.
How to cite: Smith, N.: Optimal photosynthetic strategies, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3165, https://doi.org/10.5194/egusphere-egu26-3165, 2026.
Climate change is drastically affecting the health and composition of terrestrial vegetation through increasing average temperatures and altered water availability. Terrestrial vegetation is a key mediator of global water fluxes through processes such as evapotranspiration and photosynthesis, meaning that the peril posed by the degradation of vegetation will be felt at the global scale. Because of this, there is mounting interest in modelling global vegetation water storage (Sveg) as a means to understand the role that vegetation plays in maintaining a stable climate and how this will be affected by the climate crisis.
Currently, estimates of global Sveg can be derived from satellite imagery using microwave remote sensing. The microwave signal is attenuated by the amount of water contained in vegetation and is then related to Sveg through a look-up table of land cover-specific values, known as the b parameter. Along with water storage, the b parameter is influenced by the biomass and structure of the vegetation, however the interaction between these variables and their influence on the b parameter is poorly understood. Therefore, to further elucidate the physiological component that the b parameter represents in satellite derived estimates of Sveg, it is necessary to generate independent physiologically derived Sveg estimates. Here, we present the first globally explicit trait-based map of Sveg, with vegetation separated into two physiological components: wood and leaf tissue. Phylogenetically imputed species-level values for wood density (WD) and specific leaf area (SLA) were used for 46,309 plant species, derived from field and laboratory-measured data. Wood water storage was estimated through a linear relationship with WD and biomass. Leaf water storage was estimated through a non-linear relationship with SLA and scaled to the canopy with leaf area index. Comparing our Sveg estimates with independently derived plot-level trait-based estimates demonstrated a strong correlation (R2 0.94), suggesting our phylogenetic imputation approach to be robust and scalable.
How to cite: Stewart, L., Chaparro, D., Poyatos, R., Gimeno, T., Mencuccini, M., and Binks, O.: Wood You Be-Leaf It? The First Trait-Based Map of Global Vegetation Water Storage, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2554, https://doi.org/10.5194/egusphere-egu26-2554, 2026.
Carbon allocation plays an important role in determining tree productivity and survival under environmental change. However, our understanding of how allocation patterns and their responses to drought vary among diverse functional types in tropical forests remains limited. In a tropical forest equipped with an 80-m canopy crane, we measured leaf gas exchange and water status, leaf nonstructural carbohydrates (NSCs) and phenolics, stem growth, and crown characteristics of mature trees from 18 species spanning different canopy positions, water-use and growth strategies during both the wet and dry seasons. The results show that tall canopy trees experienced stronger VPD and water stress and greater reductions in leaf gas exchange than short understory trees, leading to declines in NSCs (particularly starch) in canopy trees but increases in understory trees in the dry season. Despite changes in carbon supply, leaf phenolic levels remained remarkably stable across species, with species-specific variation explained by tree height and herbivory. With increasing height, both whole-tree leaf phenolics and NSCs increased whereas stem growth varied among canopy species. We highlight that canopy position–driven differences in resource availability and environmental stress are key for understanding and predicting carbon balance and allocation strategies in tropical forests experiencing seasonal droughts.
How to cite: Sun, C., Chen, Y., Song, Q., Fan, Z., Xu, G., Yang, J., Jin, Y., Wang, S., Gershenzon, J., Herrera‐Ramírez, D., Römermann, C., Trumbore, S., and Huang, J.: Seasonal drought leads to contrasting nonstructural carbohydrate dynamics but stable phenolic defense in tall-canopy and short-understory tropical trees, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5894, https://doi.org/10.5194/egusphere-egu26-5894, 2026.
Eurasian grapevine (Vitis vinifera L.) is one of the fruit crops affected by the ongoing climate change, which is characterized by an increased frequency of heat waves and drought events. In most viticultural areas, V. vinifera is cultivated grafted onto American rootstocks resistant to phylloxera. Only rare grapevine varieties are still cultivated ungrafted, typically in soils inhospitable to this pest and generally considered marginal for agriculture. Historic ungrafted grapevines could be a valuable genetic resource to face the climate change. On the sandy coast of Emilia-Romagna region (Italy), “Fortana” is one such variety, cultivated either self-rooted or grafted, and described as resistant to drought by local farmers. In this environment, the grafting is not necessary for plants to resist phylloxera, but could lead to some other advantages, e.g., related to the water balance.
This study aims to verify whether grafting Fortana vines in a mature vineyard has brought physiological advantages compared to self-rooting. The study took place in July 2025 in a coastal vineyard in the Ferrara province (Italy) comprising both ungrafted and grafted plants (up to 50 years old) grown without artificial irrigation. Ampelographic observations and molecular analyses (SSR) confirmed the identity of Fortana and identified the rootstock as “Kober 5BB”, known for its good adaptability to sandy soils and moderate drought tolerance. Fast chlorophyll a fluorescence was measured using a Handy-PEA fluorometer, gas exchange was assessed with a CIRAS2 Portable Photosynthesis System, and stem water potential (ψstem) was determined with a Scholander pressure chamber. Fluorometric and gas exchange determinations were performed in the morning, at midday and in the afternoon to detect possible differences in photosystem II (PSII) photoinhibition and water stress during the day.
Fluorometric analyses revealed that all plants experienced a slight degree of daily photoinhibition, although the grafted performed slightly better than the self-rooted. Gas exchange showed pronounced diurnal variations, with decreasing stomatal conductance (gs) and net photosynthesis (Pn), but without major differences between grafted and ungrafted plants. The ψstem was stable all day long, with values indicating a slight water stress in all plants. The results suggest that grafting Fortana plants could have led to a negligible benefit compared to self-rooted, unless their tendency to be less susceptible to photoinhibition may have a cumulative effect that finally results biologically relevant. To investigate more deeply such aspect, integrated information on the plant performance has been planned using carbon and nitrogen isotopic analyses of mature grapevine canes, which will be related to reference values in soil.
Acknowledgements
This research was funded by the Ministry of Research of Italy through the project PRIN2022 « Soil, water, sun: Exploring Ungrafted indigenous Italian Vitis vinifera L. varieties as a resilient resource against the effects of global climate change (EU-vitis) » (CUP F53C2400120).- 1Department of Environmental and Prevention Sciences, University of Ferrara, Ferrara, Italy (bllmtt2@unife.it)
- 2Council of Agricultural Research and Economics, Research Centre for Viticulture and Enology, Conegliano (Treviso), Italy
- 3Department of Chemical, Pharmaceutical and Agricultural Sciences, University of Ferrara, Ferrara, Italy
How to cite: Ballestriero, M., Marrocchino, E., Sansone, L., Carraro, R., Tedeschi, P., and Ferroni, L.: Adaptability of self-rooted and grafted Vitis vinifera cv. Fortana to marginal sandy soils in coastal Emilia-Romagna (Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14444, https://doi.org/10.5194/egusphere-egu26-14444, 2026.
Climate induced upslope migration of alpine plants is accompanied by a decline in atmospheric pressure, raising the question of whether plant performance at higher elevations is constrained by carbon availability and/or by water-related stress. Decreasing air pressure alters gas diffusivity, evaporative demand, and the partial pressure of CO₂, potentially shifting limitation from carbon acquisition towards plant water relations. However, in the field the impact of reduced air pressure is hardly to detect because it covaries with temperature, humidity, and radiation along natural elevational gradients.
We thus addressed this question using ecotron experiments that isolate air-pressure effects from co-varying climatic factors. Mountain grassland species and model plants with contrasting functional strategies (Arabidopsis thaliana, Trifolium pratense, Hieracium pilosella, Brachypodium rupestre) were grown under atmospheric pressures corresponding to ~1,500–4,000 m a.s.l. (85–62 kPa), while temperature, radiation and air humidity were kept equal among the treatments. We quantified traits related to gas exchange (stomatal conductance, carbon isotope discrimination), carbon acquisition and allocation (photosynthetic efficiency, carbohydrate storage, biomass production), and nutrient status (leaf nitrogen and chlorophyll).
Across species, reduced air pressure consistently lead towards higher photosynthetic energy-use efficiency and increased leaf carbohydrate pools (up to +40%), while aboveground biomass decreased. Gas-exchange revealed species-specific strategies: stomatal conductance increased or remained stable under low pressure in forb species, whereas grass responses depended on interactions with water availability. After 4 weeks results indicated a decreased carbon assimilation efficiency under low air pressure and a higher vulnerability to drought because of the higher Vapour-pressure deficit (VPD)
These short- term results suggest that reduced air pressure is a relevant parameter for upwards-migrating mountain plants and may play an underestimated role in shaping composition and performance of alpine ecosystems.
How to cite: Niedrist, G., Lembo, S., De Giuli, M., El Omari, B., Präg, N., Illmer, P., Asensio, D., and Dainese, M.: CO₂- or water-limited? Plant trait and physiological responses to reduced atmospheric pressure, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12589, https://doi.org/10.5194/egusphere-egu26-12589, 2026.
Understanding which plant belowground foraging strategies promote long-term population temporal stability is critical for understanding species coexistence in grassland ecosystems. Root trait variation is increasingly framed within a multidimensional root economics spectrum that contrasts do-it-yourself (DIY) soil exploration via fine, acquisitive roots with outsourcing of resource acquisition to mycorrhizal symbionts. While these strategies are known to shape belowground resource use, their consequences for temporal population stability remain poorly understood.
Here, we tested whether root strategies predict long-term population stability using 16 years of annual vegetation data from 150 plots in three regions of temperate grasslands in Germany. Temporal stability was quantified as the coefficient of variation in species cover and related to a comprehensive set of belowground and aboveground functional traits measured for 82 species.
Populations investing in outsourcing showed higher temporal stability, while populations with stronger DIY strategies exhibited lower temporal stability. At the trait level, collaboration-related anatomical traits, particularly cortex fraction, consistently promoted stability, while acquisitive fine-root traits were associated with higher variability. In contrast, aboveground leaf economic traits showed little explanatory power.
Our results demonstrate that root outsourcing to micorrhizal symbionts enhances long-term population stability in temperate grasslands, identifying belowground collaboration as a key axis of temporal niche partitioning and offering new insight into mechanisms underpinning species coexistence and grassland ecosystem functioning.
How to cite: Golshani, S., Bergmann, J., Gresse, J., Liancourt, P., and Májeková, M.: Population temporal stability in grasslands increases with root outsourcing to mycorrhizae, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17652, https://doi.org/10.5194/egusphere-egu26-17652, 2026.
Dryland vegetation is typically organized into discrete plant patches separated by bare soil. Vegetated patches function as resource sinks by capturing water, dust, and sediments, whereas bare areas act as sources of runoff and sediment. Although observational and trait-based studies generally indicate positive effects of plant functional diversity on dryland ecosystem functioning, identifying causal relationships and underlying mechanisms requires experimental approaches that explicitly manipulate biodiversity. Such experiments remain scarce in dryland ecosystems, particularly those addressing hydrological and geomorphological processes. Here, we present results from a large-scale biodiversity-ecosystem functioning experiment investigating how within-patch diversity, ranging from monospecific to highly diverse patches (either 1, 2, 4 or 8 species, organized in functionally contrasting groups), modulates runoff-driven source-sink dynamics in dryland systems. Using more than 600 vegetation patches established by planting one-year-old seedlings in manually dug holes, we quantified source-sink dynamics by relating vegetation productivity metrics (mean and maximum NDVI, changes in patch height, and changes in patch cover) to the characteristics of upslope bare-soil micro-catchments draining into each patch (micro-catchment area and mean and maximum flowlength). All metrics were derived from drone-based surveys conducted over a three-year period. Both source-area size and maximum flow length were positively correlated with all assessed patch performance metrics. Diversity significantly modulated the strength of these relationships, with patches containing four and eight species consistently exhibiting the strongest source-patch coupling, whereas two-species treatments showed the weakest relationships. Among patches composed of a single functional group (one or two species), small shrubs were most sensitive to source-area size, while perennial grasses showed little to no response. Overall, our results support the hypothesis that within-patch plant functional diversity enhances runoff capture and use, although some functional groups alone can also strongly increase patch sink capacity. These results have direct applications for dryland restoration, as provide evidence that planting several functionally contrasting species in a shared planting hole could promote a more efficient sink function in the vegetation patches.
How to cite: Bautista, S., Nazarova, V., Fuentes, D., Fornieles, F., and Rodríguez, F.: Increasing plant functional diversity in dryland plant patches enhances ecohydrological source-sink contribution to patch productivity, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21330, https://doi.org/10.5194/egusphere-egu26-21330, 2026.
Ning Dong1, Wang yiru1, Yuki Tsujii2, Ian Wright3, David Ellsworth3, Sandy P. Harrison4 , Iain Colin Prentice5
1College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
2Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki, 305-8687 Japan
3 Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
4Department of Geography and Environmental Science, University of Reading, Whiteknights, Reading RG6 6AB, United Kingdom
5Georgina Mace Centre for the Living Planet, Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, UK
Phosphorus (P) can be separated into five functional fractions: orthophosphate P (Pi), metabolite P (PM), nucleic acid P (PN), lipid P (PL), and residual P (PR). These fractions regulate vital functional processes, such as photosynthesis, protein synthesis, dark respiration. We have compiled a comprehensive global P fractional dataset along with leaf spectrum traits, such as LMA and leaf N. We found that leaf exists P allocation pattern according to plant function group as expected. PM shows an independent dimension, and increase toward hot and dry condition, and PN is closed related to LES traits. Soil P increase all P fractions and leaf P. lipid P (PL) decline with VPD and soil CN ratio, and increase with soil P. Together, these various environmental factors explain almost 50% of global variation in both PL and organic P. These findings provide a promising route towards an optimality-based approach to modelling leaf P and their relationships to properties of climate and soils.
How to cite: Dong, N.: Phosphorus fractions allocation patterns based on optimality theory: a global analysis , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21422, https://doi.org/10.5194/egusphere-egu26-21422, 2026.
Phosphorus (P) is vital to plant growth and is involved in different leaf physiological processes. However, whether plants strategically allocate P among distinct functions across species and habitats remains unresolved. By synthesizing a global dataset of leaf P fractions across 252 species spanning 8 biomes, we employ a Bayesian phylogenetic Dirichlet framework to decode the rules of relative allocation of leaf P fractions across species and environments. We found that leaf P partitioning is highly phylogenetically structured but also significantly shaped by soil total P. Specifically, the proportions of nucleic acids and metabolites P increase, while phospholipids decrease with soil total P concentration, suggesting a trade-off in the investment between physiological metabolism and membrane structure. Furthermore, lower investment in phospholipids is consistently associated with both higher photosynthetic P-use efficiency and internal leaf P resorption, but balances differently in the investment in other fractions. Crucially, the relationships between leaf P allocation and leaf economic traits challenge the classic growth rate hypothesis, with species possessing conservative traits, such as higher leaf mass per area and lower nutrient concentration, generally showing higher proportional P investment in metabolically active biochemicals. Notably, the directional trade-off in leaf P partitioning appears to be ecologically effective only in evergreen species. These findings are central to understanding how plants adapt to P deficiency through efficient nutrient allocation, with further implications for crop breeding and biodiversity maintenance.
How to cite: Ao, G. and zhu, B.: Leaf phosphorus fractionation underlies the plant phosphorus niche and functional adaptation globally, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7624, https://doi.org/10.5194/egusphere-egu26-7624, 2026.
Nitrogen (N) availability is a point of competition between tundra plants in a warming Arctic, where shrubs are spreading. Soil N mobilization from microbial mineralization can happen year round, and if some plants are able to access N during winter, they will have competitive advantages during warming winters with more N turnover. We therefore compared access to and retention of N during freeze-in to late winter in tundra plants from different tundra sites and explored how this may be linked to root biomass and plant functional type specific traits.
We used 15N tracers in mesocosms from around Greenland, spanning a climate gradient from High- to Subarctic climates, and analyzed N uptake and retention species-specifically in stems and leaves, and in roots, microbes and in soil solution at four different winter stages along the climate gradient. We further measured the N uptake during a simulated late winter warming event.
We found that roots and aboveground biomass took up and retained 3-8 % of the early winter-released tracer N, but that early microbial N recovery of up to 50% dominated the ecosystem N retention. Most root N uptake was found in the Low Arctic, where continuous uptake was indicated. Least winter-released 15N overall was recovered in the High Arctic ecosystem, whereas the Subarctic ecosystem had the highest 15N recovery in plant biomass, especially in stems of deciduous shrubs. While evergreen shrubs, especially Empetrum nigrum, were overall most successful at acquiring and retaining winter-released N with the current vegetation composition, the deciduous shrub Salix arctica stood out as most effective per unit biomass.
We conclude that plant-specific traits and strategies, as well as climate, controlled tundra plant N access and retention during winter. Our results reveal that tundra plants access N during winter, but that plants in the Subarctic could be better adapted to access future increased winter N compared to the High Arctic. Across climates, species-specific winter N acquisition must be considered when explaining the expansion of shrubs in the Arctic tundra.
tundra plant N access and retention during winter is controlled by plant-specific traits and strategies as well as climate. Furthermore, species-specific winter N access and acquisition must be considered when explaining the expansion of shrubs in the Arctic tundra.
How to cite: Rasmussen, L. H., Rütting, L., and Michelsen, A.: Winter climate or species-specific traits? Controls on tundra winter nitrogen uptake along an Arctic climate gradient, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2968, https://doi.org/10.5194/egusphere-egu26-2968, 2026.
In many high-latitude ecosystems, ericaceous dwarf-shrubs play a dominant role influencing patterns of biodiversity and driving ecosystem functioning. Despite this importance, dwarf-shrubs are underrepresented when modelling how vegetation influences fluxes of carbon, water and energy in land surface models. To create new plant functional types that better represent these important species and processes, we use plant functional traits to explore responses and effects to environmental and biotic interactions. While current land surface models rely on fixed trait parameters, understanding the range and drivers of intraspecific variation is essential for selecting representative values and improving predictions of biogeochemical fluxes. In the DURIN project, we examine intraspecific variability in plant functional traits focusing on the dwarf shrubs Calluna vulgaris, Empentrum nigrum, Vaccinium myrtillus and Vaccinium vitis-idaea which represent both evergreen and deciduous species and a range of the leaf economics spectrum. These keystone species were sampled in paired forested and open heathlands located at coastal and inland sites distributed in southern and northern Norway. Here we found high levels of intraspecific variation across our species, with more conservative trait expression typically exhibited in open habitats, inland and northern sites. Next we seek to investigate how these shifts in trait variation may influence carbon cycling via in-situ assessments of leaf-level thermal tolerance limits for photosynthesis and a litter transplant experiment to understand rates of litter decomposition. Developing these integrated understandings of how leaf traits influence the broader biogeochemical cycle at both local and regional scales, will provide critical insights into not only the adaptive potential of these key species, but also provide more robust parameters for inclusion in land surface models improving our vegetation-climate predictions under ongoing global change.
How to cite: Geange, S., Birkeli, K., Dange, M., Dawson, H. R., Haaversen Møllerbaug, V., Kirkhus, M., Phiri, A., Rezsöhazy, J., Sagabraaten, B., Steinli, M., Althuizen, I., Egelkraut, D., Halbritter, A., and Vandvik, V.: Linking Plant Trait Variability to Biogeochemical Cycling in High-Latitude Heathlands, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15425, https://doi.org/10.5194/egusphere-egu26-15425, 2026.
Plant trait observations provide a critical bridge between organismal strategies and ecosystem-scale biogeochemical cycling, yet trait coverage and the evidence base used for land-surface model (LSM) parameterisation remain geographically uneven. Current LSM parameterisations are biased because African floras and trait data are underrepresented in global syntheses. This limits how well LSMs represent the diversity of plant strategies across African landscapes, contributing to uncertainty and regional bias in simulations of carbon and water cycling under rapid environmental change. A key need is therefore a transparent measurements-to-models pathway that converts heterogeneous trait and botanical information into model-ready functional groupings that can directly support parameterisation and evaluation of LSMs.
Here we operationalise a transparent trait-to-PFT translation layer for LSM parameterisation. We used reproducible, rule-based workflow that could be applied across floristic regions to map African plant species represented in the TRY plant trait database to the Joint UK Land Environment Simulator (JULES) plant functional types (PFT) taxonomy. We assigned classification attributes including growth form, leaf type, leaf phenology, photosynthetic pathway, and climatic zone, and implemented decision rules to generate consistent PFT assignments. This process mapped 1603 plant species from 137 families to JULES PFTs. Our output provides JULES-ready PFT labels alongside decision metadata that document classification rules, provenance, and the inputs that supported each assignment, enabling reuse across different PFT taxonomies, as well as sensitivity testing of alternative classification choices.
Building on the capabilities of the existing TRY categorical lookup table, this exercise has yielded a five-fold increase in the number of plant trait observations linked with JULES PFTs across the continent of Africa. Using these records, we derive PFT-level trait distributions for Africa and translate them into trait-informed ranges for critical JULES vegetation parameters. We quantify how these Africa-specific ranges differ from current global default PFT values. These constraints provide a practical route to more defensible parameter choices and more targeted sensitivity analyses. Together, the dataset and parameter summaries support improved integration of existing and future plant trait data into PFT parameterisations in land surface models and similar large scale modelling exercises, to enhance the representation of African ecosystems and better constrain the uncertainty when modelling global systems.
How to cite: Akhabue, E. F., Cunliffe, A. M., Bett-Williams, K., Harper, A. B., Holden, P., and Powell, T.: Addressing the underrepresentation of African ecosystems in plant traits, adaptation, and biogeochemical cycles: Mapping traits for model parameterisation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5302, https://doi.org/10.5194/egusphere-egu26-5302, 2026.
The search for predictors of plant diversity has challenged scientists for decades. The purpose of this study was to understand the relationship between plant species richness and solar radiation in global grasslands.
We collected standardized plant species richness and plant aboveground biomass data at 150 natural and semi-natural grasslands on six continents and analyzed them together with different measures of photosynthetically active radiation (PAR) and UV-B radiation derived from satellite data (with a temporal resolution of three hours covering several decades) as well as other environmental variables.
We identified PAR as a major factor constraining plant species richness in global grasslands. We show that the strength of the negative relationship between species richness and PAR increases with increasing elevation and that species richness is more strongly correlated with intense PAR than with UV-B radiation, climate variables, and atmospheric nitrogen deposition. In addition to species richness, plant biomass was also negatively correlated with PAR at higher elevations, indicating that intense PAR also constrains plant biomass in montane grasslands.
Furthermore, we show that the decrease in plant species richness with increasing PAR is mainly caused by a decrease in species richness of forbs, sedges, and rushes. In contrast, species richness of grasses was only negatively correlated with PAR at high elevations, and species richness of legumes was not significantly correlated with PAR. The reason why species richness of grasses was not correlated with PAR across all sites is likely that grasses are better adapted to high PAR than plants of other plant functional groups. The leaf area of grasses is negatively correlated with PAR globally, and grasses accumulate larger amounts of silicon than forbs, legumes, and rushes. Silicon forms silicate minerals, so-called phytoliths, in grass leaves, which play an important role in diffusing solar radiation inside the leaves before it hits the photosystems.
Our results suggest that PAR constrains plant species richness in global grasslands and limits the extent to which plant species of specific functional groups can migrate uphill in response to climate warming.
Reference
Spohn et al.: Intense solar radiation constrains plant species richness in global grasslands. PNAS (in press).
How to cite: Spohn, M.: Intense solar radiation constrains plant species richness in global grasslands, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5789, https://doi.org/10.5194/egusphere-egu26-5789, 2026.
Understanding forest carbon fluxes is crucial for monitoring and predicting the global carbon cycle and climate-carbon interactions. Plant physiological and structural traits (PSTs) strongly influence canopy-light interactions and, in turn, forest productivity. Hyperspectral and LiDAR observations from the US National Ecological Observatory Network’s Airborne Observation Platform (NEON AOP) enable the mapping of three-dimensional (3D) spatial variability of PSTs across observed sites. PSTs (e.g. leaf nitrogen, leaf mass area, leaf area density, woody area density) determine the optical and geometric characteristics of the canopy and have a nontrivial relationship with the distribution of photosynthetically active radiation (PAR) within the canopy, the magnitude and distribution of absorbed PAR (APAR), and the influence of the diffuse PAR fraction. Therefore, linking mapped traits to total APAR and gross primary productivity (GPP) requires the modelling of within-canopy radiative transfer as well as ecosystem function. With 3D PST estimates derived from NEON AOP data alongside measurements of PAR from the AmeriFlux network, we used the Forest Light Environmental Simulator (FLiES) to model APAR in two North American deciduous broadleaf forest sites at the University of Michigan Biological Station in the northern Lower Peninsula of Michigan (US-UMB, US-UMd) with a 30-minute temporal resolution over two months centered on the NEON AOP flight period. We then trained a random forest (RF) model using AmeriFlux daytime-partitioned (DT) eddy covariance estimates of GPP, modelled APAR, and meteorological and solar data. Our results show that our RF model reliably reproduces DT GPP (R2 > 0.8) and that FLiES-derived APAR is a key predictor of GPP. Lastly, we explore how the vertical and diurnal distributions of APAR vary with canopy structural differences, and how these structural differences relate to disturbance history.
How to cite: Butterfield, Z., Dahlin, K., Shen, M., Kamoske, A., Stark, S., Serbin, S., Gough, C., and Kobayashi, H.: Integrating Hyperspectral, LiDAR, and Radiative Transfer Modeling to Predict Forest GPP, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14885, https://doi.org/10.5194/egusphere-egu26-14885, 2026.
Leaf Area Index (LAI) is a fundamental biophysical parameter for land surface process models and remote sensing applications. Accurate quantification of leaf area and biomass is essential for understanding vegetation's role in the regional carbon balance and for models simulating biogeochemical processes. Remote sensing data have been widely used in long term and large-scale LAI estimations but the critical ground truth for developing and validating LAI estimations remains challenging especially in remote areas such as Arctic regions.
This study evaluates the efficacy of low-cost proximity sensing with consumer-grade smart phone LiDAR and structure-from –motion (SfM) sampling method to derive high resolution 3D plant modelsin Kobbefjord, Greenland. These innovative ground-based datasets were compared against manual in situ LAI measurements to assess their accuracy in tundra ecosystems. We further integrated these high-resolution point clouds into a multi-tiered, data-driven framework, upscaling the measurements through UAV (drone) imagery to satellite observations. This multi-scale approach enhances our ability to e.g. monitor rapid Arctic greening and improves the precision of biophysical inputs for climate and emission models.
How to cite: Feng, S., Laursen, S. N., Grillini, F., and Westergaard-Nielsen, A.: Linking leaf area index measurements across scales from smartphone LiDAR to multi-source remote sensing observations. , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14796, https://doi.org/10.5194/egusphere-egu26-14796, 2026.
Plants using crassulacean acid metabolism (CAM) for photosynthesis are adapted to dry conditions by taking up carbon at night. Gas exchange measurements of CAM plants at the ecosystem level are rare, with only a few studies to date reporting CO2 exchange using the eddy covariance (EC) method. We monitored the ecosystem CO2 exchange of Agave sisalana using the EC method in an agricultural field in semi-arid Kenya over 65 days, starting in a wet period that gradually transitioned to a dry period. High productivity occurred during the wet period, with a mean net CO2 uptake of −1.1 µmol m⁻² s⁻¹ (dry period: +0.3 µmol m⁻² s⁻¹). This was linked to significant day- and nighttime CO2 uptake, indicating direct CO2 fixation via the C3 photosynthetic pathway during daytime. As soil moisture decreased, mean daytime net CO2 exchange increased considerably, from +1.0 to +4.0 µmol m⁻² s⁻¹, suggesting a shift towards strict CAM photosynthesis in response to soil drying. Our results demonstrate the high photosynthetic plasticity of A. sisalana with changing soil moisture and its significance for ecosystem-scale CO2 fluxes.
How to cite: Kübert, A., Kohonen, K.-M., Lohila, A., Merbold, L., Räsänen, M., Skogberg, M., Vuorinne, I., Pellikka, P., and Vesala, T.: Ecosystem-scale crassulacean acid metabolism (CAM) gas exchange of a sisal (Agave sisalana) plantation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13934, https://doi.org/10.5194/egusphere-egu26-13934, 2026.
In light of the observed changing conditions of forest growth, it is important to develop up-to-date forest growth models at the level of entire ecosystems, individual stands, and single trees. The aim of the study was to determine how multi-source variables explain the radial growth of Pinus Sylvestris and Norway spruce trees. Models for Scots Pine were developed based on over 100 000 annual observations of tree ring width from 6749 trees across 301 plots located in Poland, and for Norway Spruce, based on over 15 000 observations, 1090 trees across 57 plots. The analyzed period spanned from 2005 to 2022. Data from airborne laser scanning was used to calculate tree height, various competition indices, crown volume, and relative sunlight exposure. Other variables included: diameter at breast height, stand stock and age, climatic variables describing vegetation season and soil characteristics. Random forest models were developed. Cross-validation was applied, selecting one year of observations and random 20% of plots as test data per iteration. Models trained on all data reached around 70% explained variability, however after cross-validation explained variability dropped to around 18% and 7% for tree ring width of Scots Pine and Norway Spruce respectively. Despite the use of an extensive set of explanatory variables, big part of the variability in growth was determined by other factors and remained unexplained. The obtained results indicate the need for further research in the field of modeling diameter growth of individual trees.
How to cite: Zdunek, N., Hawryło, P., and Socha, J.: Modelling single-tree diameter increment of Scots pine and Norway spruce using multi-source tree, stand, soil, and climatic data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19870, https://doi.org/10.5194/egusphere-egu26-19870, 2026.
Posters on site: Mon, 4 May, 10:45–12:30 | Hall X1
Climate change is intensifying environmental pressures on coastal agroecosystems, particularly through increased salinization, drought, and soil degradation. These processes strongly affect soil–plant interactions and may alter the biogeochemical signatures of crops, with direct implications for food quality, traceability, and territorial resilience. Stable isotope analysis provides a sensitive integrative tool to link climatic drivers, soil properties, and plant metabolic responses.
This study investigates soil–plant continuity in Asparago Verde di Altedo PGI (Asparagus officinalis) cultivated in the eastern Po River Delta (Ferrara province, NE Italy), a low-lying coastal area highly vulnerable to climate-driven salinization, saltwater intrusion, and historical land reclamation. The PGI production area is characterized by sandy to sandy–clayey soils forming a marked inland–coastal gradient, which offers an ideal natural laboratory to assess environmental controls on isotopic signatures. Specifically, it was hypothesized that the inland-coastal gradient in soil properties had a counterpart in asparagus.
Soils were characterized from different fields cultivated with asparagus with respect to pH and elemental composition using X-ray fluorescence and ICP-MS, with particular attention to salinity-related markers (e.g. Na enrichment) and trace elements. Stable carbon and nitrogen isotope ratios (δ¹³C, δ15N) and C/N ratio were determined in soils and asparagus turions by EA-IRMS to evaluate isotopic transfer and the influence of soil geochemistry and water availability on plant metabolism. To complement isotopic evidence, the turions were phenotyped through JIP-test parameters calculated from fast chlorophyll a fluorescence induction, a non-destructive technique providing insights into photosynthetic efficiency.
Multivariate analysis shows that isotopic signatures effectively capture environmental gradients associated with salinization and soil heterogeneity, enabling discrimination of asparagus samples according to their geographical origin even at local spatial scales. Variations in δ¹³C reflect differences in water-use efficiency and carbon assimilation linked to salinity and drought stress, while δ¹⁵N records soil-related and anthropogenic influences within the PGI area. C and N parameters had interesting relationships with JIP-test parameters, strengthening their anticipated link with photosynthetic modulations as determined by soil features.
The results demonstrate the potential of stable isotope approaches to connect climate change impacts with crop biogeochemistry and metabolism, supporting food traceability, PGI valorization, and adaptive management strategies in vulnerable coastal agricultural systems.
This research was allowed by PhD fellowship granted by the EUROPEAN SOCIAL FUND P L U S - The ESF+ 2021-2027 Programme of the Regione Emilia Romagna.
How to cite: Marrocchino, E., Martina, A., Bigoni, M., Viola, I., and Ferroni, L.: Stable isotope signatures of Asparago Verde di Altedo PGI (Asparagus officinalis) along an inland-coastal soil gradient at the Po River Delta (NE Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17823, https://doi.org/10.5194/egusphere-egu26-17823, 2026.
In the current scenario of global warming, Mediterranean viticulture is increasingly facing severe stressors that threaten the sustainability and quality of production. The interaction between root system and soil profile plays a key role in regulating plant physiological resilience. While the use of rootstocks has been the standard solution against phylloxera for over a century, recent investigations are refocusing on the agronomic potential of ungrafted grapevines and their tolerance to environmental stress. In the Calabria region (Southern Italy), the local variety “Magliocco Dolce” is cultivated both self-rooted and grafted. Evaluating whether grafting provides distinct physiological advantages related to water balance and stress tolerance compared to self-rooting is crucial for future adaptive strategies.
This study aims to verify the performance of these vines. Fieldwork was initiated in July 2025 in a vineyard comprising both young ungrafted and adult grafted plants (approx. 10-15 years old). Ampelographic observations and molecular analyses (SSR) were performed to confirm the varietal identity. Physiological performance was assessed by fast chlorophyll a fluorescence using a Handy-PEA fluorometer. Furthermore, to characterize the pedological environment, soil profiles were excavated and described in both grafted and ungrafted plots, considering slope positions (upslope and downslope) to evaluate soil spatial variability.
The identity of “Magliocco Dolce N.” was confirmed and the rootstock was identified as Paulsen clones 1103 or 775. Physiological monitoring revealed a higher photosynthetic efficiency in the grafted plants . Analysis of the chlorophyll fluorescence transient (JIP test parameters) indicated that, while both plant types showed a typical morning-to-afternoon decline in performance , ungrafted vines were more susceptible to diurnal photoinhibition. The Performance Index (PITot), a sensitive indicator of plant vitality, was significantly higher in grafted vines. Similarly, energy flux parameters per photosystem II reaction center (ABS/RC, TR/RC, ET/RC) confirmed the more light energy conservation in the grafted samples. The pedological survey involved the analysis of four soil profiles in grafted and self-rooted vineyards. Results indicated that the self-rooted vineyard soils were poorly developed and weakly structured in both downslope and upslope positions. Conversely, the grafted vineyard showed significant spatial variability: the downslope profile revealed a more developed soil characterized with a well-defined structure, whereas the upslope profile presented a less evolved structure. Grafted vines generally outperformed self-rooted ones, particularly in the downslope section where developed soil profiles offer superior nutrient and water availability. The “soil-effect” cannot be overlooked when comparing grafted and ungrafted plants. However, despite exhibiting lower electron transport chain efficiency compared to the older, more established grafted plants, the self-rooted vines did not exceed critical failure thresholds, demonstrating an ability to survive in the sandy substrates.
This research was funded by the Ministry of Research of Italy through the project PRIN2022 « Soil, water, sun: Exploring Ungrafted indigenous Italian Vitis vinifera L. varieties as a resilient resource against the effects of global climate change (EU-vitis) » (CUP F53C2400120).
How to cite: Ferroni, L., Bloise, A., Fuoco, I., Vespasiano, G., Sansone, L., Carraro, R., Ballestriero, M., and Apollaro, C.: Physiological adaptability and soil-plant interaction of ungrafted vs. grafted Vitis vinifera L. in the Mediterranean context: a case study on “Magliocco Dolce” in Calabria (Southern Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17983, https://doi.org/10.5194/egusphere-egu26-17983, 2026.
Italy leads the production of pears (Pyrus communis L.) in Europe, with Emilia-Romagna as the national hub; however, for some years the sector has been facing a severe decline due to rising cultivation costs, phytopathologies, and climate instability. Since 2018, the area occupied by pear orchards has shrunk from 18,300 to 10,500 hectares. The strong prevalence of few traditional varieties (most notably the stress-susceptible Abbé Fétel) severely limits genetic diversity and adaptive capacity, underscoring the urgent need for diversified germplasm and optimized rootstock-scion combinations suited to specific pedoclimatic conditions.
To diversify the pear tree germplasm cultivated in Emilia-Romagna, comparative research focused on rootstock–genotype combinations was undertaken. This in-field study specifically aims to identify the most heatwave-resistant genotype-rootstock combinations in an experimental orchard located in the Po River Plain near Ferrara. Twenty pear genotypes (including reference cultivars Abbé Fétel and Williams), grafted on seedling rootstock, or BA29, or BA29/BH rootstocks, were planted in 2023. Soil characterization included textural, calcimetric, pH, and loss-on-ignition (LOI) analyses, together with multi-element profiling by X-ray fluorescence (XRF) and stable isotope determination (δ¹³C and δ¹⁵N ratios) by elemental analysis–isotope ratio mass spectrometry (EA-IRMS). During winter dormancy (December 2024), the youngest branches were likewise sampled to assess δ¹³C isotopic composition and C/N content. Plant physiological performance was subsequently evaluated through fast chlorophyll a fluorescence of leaves in May, June, and July 2025 to capture seasonal heatwave effects. LOI and calcimetric analyses confirmed organic carbon and carbonate contents compatible with adequate soil functionality. δ¹³C in branches ranged within a physiological range, from -28.3‰ to -25.7‰, across genotype/rootstock combinations. Chlorophyll fluorescence parameters, particularly the total performance index PItot showed marked variability among combinations and differentiated plant responses to the intense heatwave affecting Northern Italy in 2025.
These preliminary results, which are undergoing further elaboration, suggest that multi-temporal PItot determinations combined with branch δ¹³C analyses can provide a tool for the identification of optimal heatwave-resistant genotype-rootstock combinations. However, the result must be considered specific to the Ferrara orchard context, characterized by well-defined soil properties within the alluvial Po River Plain, which is intrinsically heterogenous because of sediments of different origin and strong anthropic action. Further research will look for validation of the result in other soil contexts that are relevant to periculture in Emilia-Romagna.
Research funded by the European Union – NextGenerationEU, Ministero dell’Università e della Ricerca - Piano Nazionale di Ripresa e Resilienza, D.M. 630/2024.
How to cite: Ferroni, L., Bigoni, M., Viola, I., Zaccarini, M., Farinelli, A., and Marrocchino, E.: Identifying heatwave resilient genotype-rootstock combinations in pear orchards through integrated soil and physiological analyses, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17553, https://doi.org/10.5194/egusphere-egu26-17553, 2026.
The Early World was an RNA world and started with non-coding RNA, which we know today from viroids and ribozymes. Viroids/ribozymes are the most ancient entities which can replicate, undergo mutations and evolve. They may have been autonomous in the Early World, helping build up larger structures, protocells and cells. A model how life may have evolved has been designed by Manfred Eigen by demonstrating chemical evolution with prebiotic molecules. This occurs before the biological evolution of living matter. Furthermore, M. Eigen designed a Hypercycle, an abstract model where autocatalytic self-organization occurs, self-replicating members cooperate and are linked in a positive feedback loop. It can be applied to primordial RNA molecules such as ribozymes which are essential throughout evolution of life until today. What can one learn from such a principle for extraterrestrial origin of life?
How to cite: Dr.Moelling, K.: Life started by self-organization, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3039, https://doi.org/10.5194/egusphere-egu26-3039, 2026.
Plant traits - morphological, anatomical, biochemical, physiological, or phenological features measurable at the individual level (Violle et al., 2007) - connect species richness with ecosystem functional diversity. Focusing on traits and trait syndromes is seen as a promising foundation for a more quantitative and predictive approach to biodiversity, ecology, and global change science. Although plant traits have been compiled for many years, a comprehensive database has been lacking. In 2007, the IGBP and DIVERSITAS initiative ‘Refining Plant Functional Classifications’ asked the Max Planck Institute for Biogeochemistry to develop a global plant trait database to support biodiversity research, functional biogeography, and vegetation modelling. The initiative was named TRY. With contributions of several original datasets and the most extensive integrated datasets at the time, the TRY Database immediately achieved unprecedented data coverage (Kattge et al., 2011). Since 2015, dataset owners have been able to make datasets in TRY public, and since 2019, data in TRY are freely available by default under a CC-BY license (Kattge et al., 2020). Since then, the database has received around 40,000 requests - about 20 per day. In summary, TRY has become a central hub for plant trait data.
In the context of TRY, trait data are curated to some extent: taxonomy and trait names are consolidated; for continuous traits with over 1000 records, units are standardized, major errors are corrected, and flags for outliers and duplicates are added. Data are provided in a versioned format. The current version, TRY vs. 6.0, was released in 2022. It is based on 707 datasets and contains 15.4 million trait records for 2675 traits and 306,000 taxa - mostly species.
The upcoming version, TRY vs. 7.0, is expected to be released in spring or summer 2026. It will be based on 907 datasets and include about 23.4 million trait records across 3317 traits. The presentation will focus on the upcoming version, providing details on the new coverage and outlining plans to further develop the TRY Database.
References:
Violle, C., Navas, M. L., Vile, D., Kazakou, E., Fortunel, C., Hummel, I., & Garnier, E. (2007). Let the concept of trait be functional! Oikos, 116(5), 882–892. https://doi.org/10.1111/j.2007.0030-1299.15559.x
Kattge, J., Díaz, S., Lavorel, S., Prentice, I.C., Leadley, P., Bönisch, G. et al. (2011) TRY – a global database of plant traits. Global Change Biology 17:2905–2935. https://doi.org/10.1111/j.1365-2486.2011.02451.x
Kattge, J., Bönisch, G., Díaz, S., Lavorel, S., Prentice, I.C., Leadley, P. et al. (2020) TRY plant trait database – enhanced coverage and open access. Global Change Biology 26: 119– 188. https://doi.org/10.1111/gcb.14904
How to cite: Kattge, J., Schellenberger Costa, D., Díaz, S., Lavorel, S., Prentice, I. C., Leadley, P., and Wirth, C.: TRY Plant Trait Database – the upcoming version and further development, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8942, https://doi.org/10.5194/egusphere-egu26-8942, 2026.
Upscaling traits from plant-level measurements to grid-scale predictions is crucial for accounting for biodiversity when simulating and predicting the impacts of climate change and human activities on ecosystems at large scales. However, current trait upscaling frameworks face limitations, particularly the scarcity of trait observations. Based on a dense sampling strategy on the Tibetan Plateau, this study aims to develop a robust upscaling framework that (1) provides reliable trait predictions for this region and (2) enables analysis of how sampling density affects trait prediction.
The Tibetan Plateau, known as the Roof of the World with an average elevation above 4,000 m, supports diverse zonal vegetation, both horizontally and vertically. This significant environmental and vegetation heterogeneity, combined with sparse in situ trait measurements, currently leads to high prediction uncertainty in existing global and Chinese trait maps for this region, limiting their ecological accuracy for spatial scaling on the Tibetan Plateau.
Our approach toward a more robust trait upscaling includes: 1) performing standardized trait measurements on 3,961 species-level leaf samples and 504 site-level fine root samples collected from 650 sites between 2018 and 2024, covering 12 morphological and chemical traits; 2) constructing predictor sets that include bioclimate, soil, topography, and vegetation indices; 3) training machine learning models (such as random forest, boosted regression trees, and generalized additive models), using cross-validation to evaluate performance and select optimal parameters for each trait; 4) refining plant functional type (PFT) based on regional vegetation characteristics and aligning them with a detailed 10 m resolution land cover map of the Tibetan Plateau; 5) predicting traits for each PFT and aggregating them into grid-level values using PFT abundance weighting; and 6) generating a suite of 1 km resolution trait maps. We expect this work to establish a reproducible methodological framework for trait upscaling in heterogeneous landscapes, yielding more reliable trait maps for the Tibetan Plateau and providing further insight into how sampling density influences trait upscaling.
How to cite: Jin, Y., Kattge, J., Carvalhais, N., Li, K., and Ni, J.: Mapping plant traits on the Tibetan Plateau: towards a robust upscaling framework for diverse vegetation landscapes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10247, https://doi.org/10.5194/egusphere-egu26-10247, 2026.
Grassland ecosystems dominated by herbaceous plants provide essential ecosystem services, most prominently food provision, and play a key role in the global carbon cycle and in sustaining biodiversity. They are therefore central to both human well-being, and Earth system functioning. Despite their ecological importance, grassland ecosystems and herbaceous species are insufficiently represented in dynamic global vegetation models, limiting our ability to project their responses to climate and land-use change. For example, a realistic representation of phenology of grassland ecosystems is needed for analysing management practices including grazing, cutting and ploughing. However, many vegetation models lack key grass-specific processes that determine vegetation persistence and regrowth both in unmanaged and managed grasslands. As a consequence, it remains difficult to analyse feedbacks between grassland vegetation, soils and the atmosphere and the effect management has on them.
In this study, we address these limitations by advancing the representation of herbaceous species in the dynamic global vegetation model LPJ-GUESS. We implemented a daily carbon allocation scheme, grass-specific traits for i.e. allometry and life-cycle dynamics to better capture growth and seasonal development of grassland vegetation. Model performance was assessed using European grassland FLUXNET sites. We evaluated the effects of the new model representation on biomass accumulation, carbon stocks and fluxes, both in absence of management and under different management scenarios. These developments allow for a more mechanistic simulation of grassland responses to different management regimes.
How to cite: Voss, A.-K., Olin, S., Wårlind, D., Tagesson, T., Knauer, J., and Ardö, J.: Advancing grassland process representation in the dynamic vegetation model LPJ-GUESS to evaluate management impacts, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16246, https://doi.org/10.5194/egusphere-egu26-16246, 2026.
Satellite observations show widespread vegetation greening over the last few decades, which is partially due to intensified agricultural activity, longer growing seasons, and the CO₂ fertilization effect (Zhu et al., 2016). At the same time, changes in drought and heat stress show a strong spatial heterogeneity, which complicates the attribution of observed trends in the carbon and water cycles (Greve et al., 2014). To better understand these apparently contrasting signals, we calculate trends in variables affected by water-stress dynamics and assess how trends in greenness, climate, and CO₂ influence these patterns.
To analyze these coupled processes and disentangle the effects of individual forcing variables on simulated ecosystem responses, we perform global simulations using a version of the P-model that is coupled with a Penman-Monteith evapotranspiration scheme, thereby explicitly representing coupled carbon-water processes at the land surface (Stocker et al., 2020). The model is driven by a satellite-derived, natural-vegetation-only fAPAR dataset. Within these simulations (1982 - 2024 at 0.5° spatial resolution), transpiration is separated from soil evaporation; a fixed leaf area index is used, and carbon pool dynamics are omitted. A factorial design is utilized, in which one factor (greenness, climate, or CO₂) is held constant at a time to identify the primary drivers of change. These simulations address our research question of which drivers, including CO₂, Vapor Pressure Deficit (VPD), precipitation, and Fraction of Absorbed Photosynthetically Active Radiation (fAPAR), contribute to changes in variables that are likely to respond differently to drought trends, such as gross primary productivity (GPP), evapotranspiration (ET), soil moisture, runoff, and water-use efficiency of photosynthesis.
This study provides a consistent quantification of trends across multiple interrelated variables associated with global water and carbon cycling and clarifies the mechanistic basis for apparently contrasting trends reported for individual variables.
Sources
Zhu, Z. et al. (2016) “Greening of the Earth and its drivers,” Nature Climate Change, 6(8), pp. 791–795. doi: 10.1038/nclimate3004.
Greve, P. et al. (2014) “Global assessment of trends in wetting and drying over land,” Nature Geoscience, 7(10), pp. 716–721. doi: 10.1038/ngeo2247.
Stocker, B. D. et al. (2020) “P-model v1.0: an optimality-based light use efficiency model for simulating ecosystem gross primary production,” Geoscientific Model Development, 13(3), pp. 1545–1581. doi: 10.5194/gmd-13-1545-2020.
How to cite: Kurth, A., Grossi, F., Bernhard, F., and Stocker, B. D.: Attributing Global Carbon and Water Cycle Trends Using Factorial Ecosystem Simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16975, https://doi.org/10.5194/egusphere-egu26-16975, 2026.
Understanding how the relative availability of nitrogen (N) and phosphorus (P), together with water supply, influences plant photosynthesis and carbon allocation is crucial for accurate land surface models. Eco-evolutionary optimality theory provides a theoretical framework to model ecosystem responses and posits that carbon assimilation is optimized through coordinated investments in photosynthetic capacity and transpiration by minimizing their combined costs. Yet, it remains unclear how the availability of water and nutrients influences the leaf-level investments in photosynthetic capacity and transpiration.
We measured photosynthetic and leaf structural traits across N to P availability gradients in the ecosystems of Jurien Bay and Warren River in Western Australia. Both systems occur on soils developed on coastal sands and are arranged along chronosequences, but differ markedly in climate. Mean annual rainfall increases from 533 mm y⁻¹ at Jurien Bay in the north to 1185 mm y⁻¹ at Warren River in the south, while mean annual temperature decreases from 19.0 °C at Jurien Bay to 15.2 °C at Warren River.
Across gradients of N and P availability, photosynthetic capacity traits (Asat, Amax, Vcmax, Jmax) showed relatively modest variation compared with leaf structural traits (leaf N, leaf P, LMA) in both ecosystems. The ratio of leaf interior to atmospheric CO2 concentrations (Ci / Ca) showed a positive relationship with the balance of N versus P availability in Warren River, but not in Jurien Bay. Differences in Ci / Ca between ecosystems suggest shifts in the coordination between carbon gain and water loss that were not fully explained by differences in photosynthetic capacity alone, and suggest interaction between water and nutrient availability.
Our work presents new observations on leaf trait responses across natural nutrient gradients that contribute to our understanding of how nutrient and water availability jointly shape the coordination between photosynthetic capacity and stomatal regulation.
How to cite: Scheifes, D., Lankhorst, J., Kim, J., Liu, S. T., Morfopoulos, C., Lambers, H., Drake, P., Rebel, K., and de Boer, H.: Leaf trait responses to soil nutrient gradients across contrasting rainfall regimes in Western Australia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17742, https://doi.org/10.5194/egusphere-egu26-17742, 2026.
Leaf Chlorophyll Content (LCC) is an important proxy for photosynthetic capacity. Despite a large body of literature on the LCC estimation, how and why changes in foliar structure influence LCC estimation remain uncertain. This uncertainty is particularly relevant for crops, in which foliar structure undergoes distinct transitions across growth stages. As a result, the dynamics of the vegetative stage and the stability of the reproductive stage might cause different performances of LCC estimation approaches. To address this issue, here we aim to understand the impact of the crop growth phase on the LCC estimation performance and underlying mechanisms. We measured hyperspectral reflectance data and collected chlorophyll content destructively from the Seoul National University’s experiment farm in Suwon, South Korea. Using the dataset, we tested empirical, statistical, physical, and machine learning-based approaches for estimating rice LCC throughout the season from emergence to maturity. Our preliminary findings revealed that the estimation in the post-heading (i.e., reproductive) phase outperforms the pre-heading (i.e., vegetative) phase in all approaches. We further examine the mechanisms responsible for this phase-dependent performance difference and discuss strategies to achieve more robust LCC estimation. This study highlights the importance of understanding crop phenological dynamics in LCC estimation and will contribute to the improved monitoring of crop productivity as well as crop growth modeling.
This work was supported by NRF, SNU Creative Pioneering Research, KEITI, LS Mtron.
How to cite: Ryu, S., Park, H., and Kimm, H.: Impacts of Phenological Dynamics on the Estimation of Leaf-scale Chlorophyll Content in Rice Using Hyperspectral Spectroscopy, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16583, https://doi.org/10.5194/egusphere-egu26-16583, 2026.
How to cite: Aleixo, I., Ziccardi, L., Garcia, S., Damasceno, A., Lima, B., Soares, J. C., Takeshi, B., Ferreira Domingues, T., Lapola, D., Nobre Quesada, C. A., and Nelson, B. and the AmazonFACE team: Leaf age controls photosynthetic efficiency and energy partitioning in Amazonian trees, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22811, https://doi.org/10.5194/egusphere-egu26-22811, 2026.
Increases in aridity due to climate change in global drylands have led to changes in ecosystem structural and functional attributes, including shrub biomass. However, little is known about climate triggers of change in shrub biomass and the potential mechanism driving this process. Herein, we measured variations in shrub biomass and leaf functional traits in a dominant leguminous shrub species, Caragana versicolor Benth., along an aridity gradient in high-elevation regions of the southwestern Tibetan Plateau. We found an abrupt increase in C. versicolor cover and biomass beyond an aridity point of 0.35, at which C. versicolor leaf functional traits shifted from allocating N to the leaf (increasing Nmass) to modifying leaf anatomical structure (decreasing SLA) in response to increasing aridity. Leaf Pmass paralleled the changes of Nmass, while leaf N:P ratio maintained a constant value along the aridity gradient. Increased Nmass and decreased SLA consequently led to an increase in leaf δ13C (i.e., an indicator of water-use efficiency). Furthermore, aridity showed direct and indirect effects through interactions with leaf functional traits on C. versicolor biomass across the aridity gradient. Overall, our data show that shrub species in drylands cope with increasing aridity through changes in leaf functional traits, thereby formulating a leaf traits-biomass linkage. This process is crucial to understand plant dynamics under increases in aridity expected with climate change in many drylands.
How to cite: Cui, G., Zhang, L., Pugnaire, F. I., and Liang, E.: Aridity threshold triggers abrupt increase in shrub biomass through changes in leaf functional traits, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3812, https://doi.org/10.5194/egusphere-egu26-3812, 2026.
Fungi are one of the key components in the terrestrial carbon cycle, performing a significant part of the decomposition process. Without them, the degradation of organic matter would be much slower and more limited. While fungi consume large amounts of C in forested ecosystems, quantifying how much this contributes to the overall decomposition-derived CO2 is difficult. Here, we show that radiocarbon can be a useful tool both for understanding more about the activity of these fungal species and how they contribute to the transit time of C in forested ecosystems. Since the cessation of atmospheric nuclear testing, the declining level of atmospheric 14C has made it possible to date when carbon was fixed from the atmosphere with even annual precision (Hua et al., 2022). Atmospheric 14C is naturally incorporated into recent biological materials through photosynthesis, naturally labelling them and indicating how long-ago C in different tree organs and tissues was fixed. Radiocarbon measurements have shown that some mycorrhizal fungal species use carbon that is quite recently fixed, while saprophytic fungi that mainly consume dead organic matter incorporate C fixed years to decades previously in their tissues (Hobbie et al., 2002).
For our studies, we selected saprobiotic, wood-decomposing fungi from forests in Thuringia, Germany. Our results using 14C analysis by accelerator mass spectrometry show that even when growing on living trees, these fungi use carbon fixed up to ~30 years ago to produce their fruiting bodies. Fungi sampled on dead trees can use carbon fixed on average <60 but > 40 years ago to create their fruiting bodies. For four selected trees, we compared the age of the trees estimated from tree rings with the mean radiocarbon age of xylophagous fungi. It was determined that the 14C age of the fungi was closely aligned with the mean age of the tree, thereby indicating a widespread infection within the tree prior to the formation of a fruiting body. These results provide information on the age and the physical location of C substrates used by wood-decomposing fungi and provide a tracer to indicate the importance of decades-old wood decomposition to the overall transit time of C in forested ecosystems.
References
Hobbie, E. A., Weber, N. S., Trappe, J. M., & Van Klinken, G. J. (2002). Using radiocarbon to determine the mycorrhizal status of fungi. New Phytologist, 156(1)
Hua, Q., Turnbull, J. C., Santos, G. M., Rakowski, A. Z., Ancapichún, S., De Pol-Holz, R., Hammer, S., Lehman, S. J., Levin, I., Miller, J. B., Palmer, J. G., & Turney, C. S. M. (2022). Atmospheric radiocarbon for the period 1950–2019. Radiocarbon
How to cite: Varga, T., Sierra, C. A., Günther, A., Herrera-Ramirez, D., and Trumbore, S.: Radiocarbon measurements of saprobiotic (wood-decomposing) fungi provide insights into the age distribution of decomposing wood, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6753, https://doi.org/10.5194/egusphere-egu26-6753, 2026.
Phenotypic plasticity describes the ability of a species to adjust its phenotype in response to environmental variation. While functional trait plasticity is well documented for several native European tree species (e.g., Fagus sylvatica, Quercus petraea), much less is known about the capacity of non-native species to adjust to contrasting pedo-climatic conditions. This knowledge gap is increasingly relevant because species originating from drought-prone regions are receiving growing attention as potential candidates for assisted migration strategies aimed at mitigating climate-change impacts on forests.
To evaluate trait plasticity and drought tolerance in non-native tree species, we take advantage of a multi-site plantation established in 2012 along a hydroclimatic gradient spanning Switzerland and Germany. For each species, individuals from the same source population were planted after 2–3 years of nursery growth at each site in a randomized block design. The study sites differ strongly in long-term precipitation (1984–2024), with the Swiss site Mutrux being the wettest (MUT, 1324 mm), followed by the German sites Schmellenhof (SCH, 750 mm), Grossostheim (GRO, 635 mm) and Oldisleben (OLD, 481 mm). In addition, sites vary in subsurface properties and soil texture, which ultimately modulate plant-available water.
Across 2024 and 2025, we monitored key meteorological variables (air temperature, precipitation, relative humidity and photosynthetically active radiation), soil water potential and soil temperature, and we used phenocams to assess the timing of phenological events over the growing season. In summer 2024, we sampled branches from five non-native species (Tilia tomentosa, Fagus orientalis, Abies bornmuelleriana, Cedrus libani and Tsuga heterophylla) and a native reference species (Quercus robur in GRO and SCH, and Quercus petraea in MUT and OLD). We assessed predawn leaf/needle water potential and collected vegetative material to examine the hydraulic, morphological and anatomical properties of photosynthetic organs. In summer 2025, we revisited the same individuals to determine the turgor loss point (TLP) of leaves and needles as a functional proxy for drought tolerance. We also use tree growth (diameter and height) and vitality inventories as traditional indicators of species performance.
We hypothesize that species showing greater trait plasticity across sites represent better candidates for assisted migration, as they may display higher adaptive potential to local pedo-climatic conditions.
How to cite: Fabiani, G., Vitasse, Y., Perrin, E., Vollenweider, P., Glatthorn, J., Frischbier, N., Wimmer, N., and D'Odorico, P.: Can trait plasticity across a pedo-climatic gradient predict future-climate suitability in non-native tree species?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11831, https://doi.org/10.5194/egusphere-egu26-11831, 2026.
The maximum carboxylation rate (Vcmax) and maximum electron transport rate (Jmax) are key parameters characterizing the photosynthetic performance of plants. To inform modelling efforts and improve our understanding of spatiotemporal variations of these key plant traits, it is important to increase measurement efforts. However, measuring these parameters is challenging due to the expensive gas exchange equipment involved as well as the time needed for the response curve measurements. While there have been recent advances in faster measurement/estimation protocols such as the one-point method and other estimation approaches based on spectral reflectance measurements, direct comparisons of these approaches have not been reported. Furthermore, there appears to be untapped potential using chlorophyll fluorescence-based approaches. Key aspects for comparing methods beyond the accuracy of estimation include the speed and cost of measurement instruments.
Here, we evaluate and compare approaches based on gas exchange, chlorophyll fluorescence and spectral reflectance measurements for estimating Vcmax and Jmax parameters using data from 37 broadleaf tree species grown in an arboretum. We found that active chlorophyll fluorescence had the best performance for Jmax, while for Vcmax, single point gas exchange measurements could be used in ways that considerably improve over the one-point method. The spectral reflectance-based approach had comparable performance as the conventional one-point method.
How to cite: Dechant, B.: Comparing approaches for fast estimation of photosynthesis parameters, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13058, https://doi.org/10.5194/egusphere-egu26-13058, 2026.
Drought stress constrains the productivity of terrestrial ecosystems and distribution of plant species. To withstand drought stress, plants have evolved a wide range of water-use strategies. Despite the critical function of roots in whole-plant water regulations, drought strategies have been primarily studied from an aboveground perspective. Our knowledge of how fine-root traits are related to aboveground hydraulic traits remains limited. Here, we compiled a global dataset comprising five aboveground plant hydraulic traits (the xylem water potential at 50% loss of hydraulic conductivity [P50], the water potential at turgor loss point [πtlp], maximum xylem conductivity per unit sapwood area [Ks], the leaf-to-sapwood area ratio [Al:As], and wood density [WD]) associated with water-use strategies and the four fine-root traits from the root economics space (mean root diameter [MRD], specific root length [SRL], root tissue density [SRL], and root nitrogen concentration [RN]). We then investigated how and to what extent the global diversity in ecological strategies of four root economics space traits relate to aboveground hydraulic traits contributing to drought resistance. We found a slight trend towards acquisitive woody species with higher RNC and lower RTD having lower drought resistance in aboveground tissues (less negative P50 and πtlp and higher Ks and Al:As). Outsourcing woody species with thicker roots displayed a tendency towards slightly higher drought resistance (more negative P50 and πtlp and higher Ks and Al:As) than thin-rooted woody species. The weakness of these relationships highlights that aboveground plant adaptations to drought might be largely independent from classical axes of fine root ecological strategies. This could indicate a decoupling between above- and belowground strategies of drought adaptations, or that other root traits could provide more efficient adaptations to drought stress and be more strongly coordinated with aboveground hydraulics.
How to cite: Sanaei, A., Saxena, S., Mueller, K. E., McCormack, M. L., Schuldt, B., Laughlin, D. C., Rosado, B. H., Freschet, G. T., Addo-Danso, S. D., Barry, K. E., Bergmann, J., Eisenhauer, N., Florentin Clemens, J., Poorter, H., Olde Venterink, H., De Vries, J., Weemstra, M., Mommer, L., and Weigelt, A. and the Anvar Sanaei, anvar.sanaei@uni-leipzig.de: On the relationship between root economics and plant hydraulic traits, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14248, https://doi.org/10.5194/egusphere-egu26-14248, 2026.
Water-use efficiency (WUE) is a key physiological trait for understanding forest adaptation to rising atmospheric CO₂. However, under conditions of elevated CO₂ and increasing atmospheric deposition of nitrogen (N) and phosphorus (P), the responses of vegetation in tropical montane forests in terms of WUE remain understudied. This study investigates WUE, estimated from stable carbon (δ¹³C), and also analyzes oxygen (δ¹⁸O) isotope compositions across six tree species in a long-term Nutrient Manipulation Experiment (NUMEX) located along an elevational gradient (1000, 2000, and 3000 m a.s.l.) in Ecuador. We assessed whether nutrient addition influences tree physiological responses in terms of iWUE and how these responses vary across elevations.
Preliminary results indicate species-specific and elevation-dependent differences in isotopic composition and intrinsic water-use efficiency (iWUE). Nutrient addition treatments (N and P) did not result in statistically significant changes in iWUE compared to control plots, suggesting that nutrient availability is not the primary driver of iWUE variability in the studied species. However, δ¹⁸O appeared more sensitive to nutrient inputs than iWUE. Pouteria torta, Alchornea lojanensis, and Myrcia sp., exhibited significant δ¹⁸O responses under nutrient addition, reflecting contrasting physiological strategies among taxa. These responses may indicate compensatory mechanisms that help maintain relatively stable iWUE across treatments. However, this interpretation remains preliminary and requires further analysis.
Isotopic composition and iWUE varied consistently along the elevational gradient. Both iWUE and δ¹³C followed an inverted U-shaped pattern, with slightly higher values at 2000 m. On the other hand, δ¹⁸O values were more enriched and similar at 1000 m and 2000 m, consistent with higher temperatures and evaporative demand at lower elevations. Overall, climatic factors associated with elevation exert stronger control over iWUE and isotopic signatures than nutrient availability.
Although preliminary, these findings provide new insights into water-use strategies of tropical montane tree species and highlight the importance of long-term nutrient manipulation experiments for addressing knowledge gaps in tropical forest eco-physiology under environmental change.
How to cite: Chávez-Pacheco, A., Bauters, M., Báez, S., León-Yánez, S., Homeier, J., Palomeque, X., and Verbeeck, H.: Water Use Efficiency content under fertilization schemes in an elevational gradient– Preliminary results from Nutrient Manipulation Experiment in Ecuador, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19064, https://doi.org/10.5194/egusphere-egu26-19064, 2026.
Low temperature is one of the main factors affecting plant growth and propagation, and determining species-specific high elevation and high latitudinal limits of temperate trees. Chilling generally refers to low but nonfreezing temperatures, ranging from 0°C to 15°C, that negatively impact biological processes. While our understanding of the direct cold temperature induced restrictions of cambial and meristematic activity has increased substantially over the last decades, other physiological effects that might also contribute to the cold temperature limit of tree growth have gained much less attention so far. Especially, the potential effects of restricted water uptake and deteriorated hydraulic relations at low root zone temperatures might be additional drivers for the cold limit of tree growth. To explore how low temperatures limit growth by restricting root hydraulic conductance in temperate trees, we applied 2H‐H2O pulse‐labelling to quantify the water uptake and transport velocity from roots to leaves in seedlings exposed to constant 15°C, 7°C or 2°C root temperature, but identical aboveground temperatures between 20°C and 25°C in greenhouse. This study aimed to specifically explore (1) if hydraulic constrains induced by low root temperatures can be a cause for the species-specific elevational distribution limits of European temperate tree species; (2) if physiological adjustments of root water uptake in response to a short-term low root temperature stress of up to 20 days can be identified in different functional plant types; and (3) if there is a potential for cold acclimation of root water uptake in tree seedlings that acclimated at cold and warm conditions. This study firstly highlighted low temperature‐induced hydraulic constraints contribute to the cold distribution limits of temperate tree species and are a potential physiological cause behind the low temperature limits of plant growth in general. We additionally confirmed the accumulation of cold effects on water permeability of cell membrane in roots, or a controlled reduction of root water conductivity would be a potentially physiological reason causing winter dormancy in temperate trees. We finally revealed that lower montane temperate tree species possess a greater capacity to acclimate to long-term cold acclimation, potentially enabling them to migrate to higher elevations through improved cold sensitivity of root hydraulic conductance while lacking in upper montane species. This study largely concur with the existing concepts of the biological mechanisms responsible for the cold‐temperature limits of temperate trees.
How to cite: Li, Y., Liang, E., and Hoch, G.: Inter- and Intraspecific Acclimation of Hydraulic Functions to Low Temperature in Temperate Tree Species, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17102, https://doi.org/10.5194/egusphere-egu26-17102, 2026.
Posters virtual: Tue, 5 May, 14:00–18:00 | vPoster spot 2
EGU26-18092 | Posters virtual | VPS5
Linking soil texture and organic carbon to leaf chlorophyll fluorescence in Pyrus communis orchards: a multi-site study in Emilia-Romagna, ItalyTue, 05 May, 14:21–14:24 (CEST) vPoster spot 2
Since 2011 in Italy the surface area cultivated with pear tree (Pyrus communis L.) decreased from 35,400 ha to approximately 23,700 ha in 2023, driven by escalating production costs, stagnant market prices, and recurrent phytopathological challenges. Additionally, this decline has been hypothesized to be causally linked to progressively unfavorable climatic conditions, characterized by rising temperatures, frequent summer heatwaves exceeding 35°C, and reduced precipitation. The objective of this study is to identify the most effective soil–plant relationships across Emilia-Romagna, which is the leading Italian region for pear production. We aim at providing a scientific basis for adaptive management strategies linked to regional pedoclimatic variability, so as to support the future of the Italian periculture.
Three experimental orchards were located in the provinces of Ferrara, Modena and Ravenna, which are key districts in Italy for periculture were set up in 2023. Agro-meteorological conditions were continuously monitored through an online automated system. Soil samples were thoroughly characterized with respect to their texture, calcium carbonate content, pH, loss on ignition LOI, multi-element profiling by X-ray fluorescence (XRF). To link soil properties with the plant performance, fast chlorophyll a fluorescence was measured in leaves in June 2025 on BA-29 grafted trees and the PItot (total performance index) was calculated, which represents a synthetic indicator of photosystem II efficiency.
Soils at the Modena site were predominantly sandy, deriving from Apennine sediments, whereas soils from Ferrara and Ravenna sites exhibited a higher clay content resulting in greater, water-holding capacity. XRF analyses indicate that elemental concentrations at all sites were within expected background levels. LOI and calcimetric analyses were higher in Ravenna soils compared to those from Ferrara and Modena, indicating a greater organic matter and carbonate content. At the Modena site, trees exhibited significantly lower PItot values than those observed in Ferrara and Ravenna sites, This pattern is attributable to the higher sand fraction, which promotes rapid water drainage and reduced nutrient retention in contrast to clay-rich soils where enhanced water and nutrient availability can support improved photosynthetic performance performance. A relationship could also be envisaged found between soil organic carbon content and PItot. Because meteorological conditions were comparable and the germoplasm was uniform across the three sites, the observed differences in photosynthetic performance can be primarily ascribed to soil properties. These location-specific soil–plant correlations can inform precision agriculture practices, rootstock-scion selection, and adaptation strategies to enhance the resilience of pear orchards under changing climate conditions.
Research funded by the European Union – NextGenerationEU, Ministero dell’Università e della Ricerca - Piano Nazionale di Ripresa e Resilienza, D.M. 630/2024.
How to cite: Bigoni, M., Marrocchino, E., Viola, I., Zaccarini, M., Farinelli, A., and Ferroni, L.: Linking soil texture and organic carbon to leaf chlorophyll fluorescence in Pyrus communis orchards: a multi-site study in Emilia-Romagna, Italy , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18092, https://doi.org/10.5194/egusphere-egu26-18092, 2026.
EGU26-8969 | ECS | Posters virtual | VPS5
From isotopic fingerprints to functional diagnosis in Italian red chicory: linking δ¹³C and δ¹⁵N to photosynthetic performance across geography and genotypeTue, 05 May, 14:24–14:27 (CEST) vPoster spot 2
Stable carbon and nitrogen isotopes are widely applied to infer plant water-use efficiency and nutrient dynamics; however, their physiological interpretation remains uncertain when isotopic signals are not supported by functional measurements. Here, we combine elemental and isotopic analysis (EA-IRMS; δ¹³C, δ¹⁵N, %C, %N and C/N ratio) with fast chlorophyll a fluorescence assessed in vivo through the JIP-test (Handy-PEA) to resolve the physiological meaning of isotopic variability across two genotypes and three geographical contexts of typical Italian red chicory.
In December 2024, leaves and roots of two Cichorium intybus cultivars (“Rosso precoce di Chioggia” and “Rosso precoce di Treviso”) were sampled across three sites, resulting in four genotype–site combinations. Plants were collected at their areas of origin, as defined by Protected Geographical Indication (PGI, Chioggia and Treviso), and outside the PGI area in Massenzatica (Ferrara, Italy), where both cultivars are cultivated in a sandy coastal soil. Isotopic and elemental analyses revealed a pronounced site-dependent differentiation. Leaf and root δ¹³C values varied among sites, indicating substantial long-term differences in C discrimination, related to the balance between transpiration and CO₂ assimilation, which seemed more favourable in Chioggia. δ¹⁵N further discriminated sites and cultivars, highlighting marked differences in N dynamics and internal allocation, although without clear attribution to specific sources.
To assess whether isotopic shifts reflected adaptive regulation or functional impairment, chlorophyll fluorescence transients (OJIP) were analysed using JIP-test parameters. All samples exhibited the typical polyphasic OJIP pattern, yet clear differences emerged between cultivars and sites. Across the entire induction curve, the Treviso PGI transient were consistently higher at the J and I steps than the other samples. This pattern was associated with increased light absorption and energy dissipation per photosystem II reaction centre (ABS/RC, DI₀/RC), reduced electron transport efficiency (ET₀/RC), and lower probabilities of electron transfer to photosystem I end acceptors (ψ(RE₀), δ(RE₀)), indicating a tendency to over-reduce the electron transport chain, probably driven by downstream limitations in electron utilisation.
Overall, our results demonstrate that a more negative δ¹³C, while implicating a better water use efficiency, does not necessarily reflect an overall better plant adaptation, which could be affected by some biochemical photosynthetic constraints. Integrating EA-IRMS with JIP-test fluorescence analysis provides a robust framework to discriminate between stomatal regulation and biochemical limitation, improving the mechanistic interpretation of isotopic markers for geographical fingerprinting and genotypic differentiation in climate-sensitive agroecosystems.
This research was allowed by phD fellowship granted by EUROPEAN SOCIAL FUND P L U S - The ESF+ 2021-2027
Programme of the Regione Emilia Romagna
How to cite: Martina, A., Ferroni, L., and Marrocchino, E.: From isotopic fingerprints to functional diagnosis in Italian red chicory: linking δ¹³C and δ¹⁵N to photosynthetic performance across geography and genotype, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8969, https://doi.org/10.5194/egusphere-egu26-8969, 2026.
Posters virtual: Thu, 7 May, 14:00–18:00 | vPoster spot 2
EGU26-21475 | ECS | Posters virtual | VPS6
Drought resilience and fruit performance in strawberry tree (Arbutus unedo L.) populations: ecophysiological screening and postharvest behaviourThu, 07 May, 14:39–14:42 (CEST) vPoster spot 2
Climate change is increasing the frequency and intensity of drought and heat events in Mediterranean regions, urging the need for resilient fruit crops that link stress tolerance to relevant fruit quality traits. My PhD project focuses on the strawberry tree (Arbutus unedo L.), an underutilised Mediterranean evergreen fruit species of considerable ecological relevance in Southern Europe, with a recognised capacity to cope with diverse abiotic and biotic constraints. The project objective is to characterise six Italian A. unedo populations in terms of physiological performance under water-limited conditions and fruit quality characteristics. The primary step is to select provenances with contrasting pedoclimatic characteristics and to use calculated climatic indices (e.g., Emberger’s Q2) across an aridity–temperature gradient. These provenances are then screened for constitutive traits under well-watered conditions combining measurements of xylem vulnerability to embolism formation (P50), water-use strategy (e.g., minimum epidermal conductance, gmin; specific leaf area, SLA), and cellular drought tolerance derived from pressure–volume analysis (turgor loss point, TLP; osmotic potential at full turgor, π₀; and modulus of elasticity, ε). After that, inducible trait modifications are tested under water stress and recovery conditions, monitoring gas exchange, plant water relations, chlorophyll fluorescence parameters, hydraulic resistance, and growth. In parallel, a core component of the work investigates fruit physiological performance across different ripening stages (identified by skin colour) and during post-harvest storage. Fruits, harvested at the yellow–orange stage, are analysed for respiratory activity using a custom fruit chamber coupled to a LI-COR 6800 system. Post-harvest dynamics are monitored under two storage treatments (ambient temperature vs. 4 °C) and related to quality attributes, including colour development, soluble solids (°Brix), firmness, weight loss, pectin content, sugar profile, and polyphenol-related traits. Within this post-harvest study, the project also considers the use of edible coatings as a practical tool to modulate storage techniques and help preserve the quality attributes of this perishable fruit. Therefore, integrating provenance screening with fruit respiration and post-harvest physiology provides a practical basis for selecting A. unedo genotypes with improved drought resilience and high fruit yield and quality, thereby fostering A. unedo cultivation in Mediterranean areas under a changing climate.
How to cite: Pascucci, G., Alderotti, F., Lo Piccolo, E., Beltrami, S., Detti, C., Baptista, A., Palchetti, V., Bini, L., Ferrini, F., Antunes, M. D., Giordani, E., Brunetti, C., and Gori, A.: Drought resilience and fruit performance in strawberry tree (Arbutus unedo L.) populations: ecophysiological screening and postharvest behaviour , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21475, https://doi.org/10.5194/egusphere-egu26-21475, 2026.
