Tree physiology最新文献

{"title":"Physiological responses and morphological adjustments in provenances of two woodland species in a chronic drought experiment.","authors":"Rhys Browning, Stefan K Arndt","doi":"10.1093/treephys/tpag117","DOIUrl":"10.1093/treephys/tpag117","url":null,"abstract":"<p><p>Drought-induced tree dieback is impacting forest and woodland ecosystems. One approach to mitigate this is to plant better adapted genotypes of species from warmer and drier climates. This requires understanding drought adaptation both interspecifically and intraspecifically, which we investigated in this common garden experiment. Six genotypes from two related Eucalyptus species, Eucalyptus microcarpa Maiden and Eucalyptus melliodora A.Cunn. ex Schauer, were selected from geographically disjunct locations, five of which encompass the drier ranges of each species. One-year-old saplings were planted in soil under a rainout shelter. After a 5-month adjustment period, irrigation was withheld for 17 weeks to emulate drought, while control trees were irrigated twice weekly. Predawn (Ψpd) and midday (Ψmd) water potentials and stomatal conductance (gs) was measured weekly. Trees were harvested at the end of the drought period, and biomass and leaf osmotic potential were measured. We observed significant differences between species, and only limited evidence for intraspecific variation. Neither species developed substantial water deficits during the drought, but both species exhibited osmotic adjustment. Ψpd and Ψmd were significantly lower and gs was higher in droughted E. microcarpa in comparison with droughted E. melliodora, however the differences were small. Decreases relative to control trees in biomass were greater in E. microcarpa (57%) than E. melliodora (41%). Root:shoot ratios in droughted trees were comparatively greater than well-watered trees in both species, however, dry root weight was greater in E. melliodora across both treatments. Only E. microcarpa had significantly lower specific leaf area (10%) and tree height (26%) in comparison with well-watered trees. Provenances of E. microcarpa from drier regions exhibited less negative Ψpd, less osmotic adjustment and comparatively lower height in droughted vs well-watered trees. Our results highlight the complexity of local drought adaptation and that morphological changes may be as important as physiological trait responses for drought resistance.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13618798/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148798385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"When the night is not long enough: soil drying constrains nighttime tree rehydration, setting a physical limit to stomatal regulation.","authors":"Julian Schoch, Lorenz Walthert, Peter Lehmann, Andrea Carminati","doi":"10.1093/treephys/tpag119","DOIUrl":"10.1093/treephys/tpag119","url":null,"abstract":"<p><p>Plants are often assumed to optimize carbon assimilation against water loss through stomatal regulation, responding instantaneously to varying atmospheric demand and soil water supply. However, a growing body of work highlights the importance of nighttime recovery processes for understanding plant water use, yet nighttime processes are not considered in existing supply-demand models. Here, we extend an existing supply-demand model by including flux imbalances between atmospheric demand and soil supply buffered by plant water storage. The flux imbalances accumulate during the day and are compensated overnight. Applying the conceptual model to field data from Quercus pubescens Willd., we show that progressive soil drying constrains the rate of nighttime rehydration. Precisely, below a critical soil water potential threshold (ψsoil,crit), nighttime rehydration begins to decline because rehydration rates become too low relative to the duration of the night ('the night is not long enough'). This threshold marks a transition beyond which maintaining high transpiration rates becomes increasingly risky. The observations show that stomatal regulation begins near this threshold, pointing to the concomitance between daytime stomatal regulation and limited nighttime rehydration. These results suggest that progressive soil drying constrains nighttime rehydration and reveal a critical hydraulic threshold that coincides with the onset of stomatal regulation and highlight that plant water use is constrained not only by daytime fluxes but also by nighttime recovery.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13623410/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148798149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Near-synchronous xylem width increase and biomass production in European beech revealed by X-ray micro-computed tomography.","authors":"Kobe Happaerts, Lorène Julia Marchand, Jan Van den Bulcke, Patrick Fonti, Louis Verschuren, Vladimir Matskovskiy, Jozica Gričar, Romain Lehnebach, Bert Gielen, Matteo Campioli","doi":"10.1093/treephys/tpag106","DOIUrl":"10.1093/treephys/tpag106","url":null,"abstract":"<p><p>Understanding the intra-annual timing of carbon allocation into wood is critical for linking environmental variability to forest carbon sequestration. We quantified the seasonal dynamics of xylem width increase and xylem biomass production in European beech (Fagus sylvatica) in Belgium during two contrasting growing seasons, a year characterized by a severe spring drought and peak summer hot drought (2020) and a mesic year (2021), using high-resolution X-ray micro-computed tomography (XμCT). Point dendrometer and microtomy measurements were used for validation and comparison. Both xylem width increase and cumulated xylem biomass production followed a sigmoidal seasonal trajectory in both years. Contrary to patterns commonly reported for conifers with a clear early- to latewood transition, the temporal lag between xylem width increase and xylem biomass production was minimal (<3 days) and statistically insignificant, indicating near-synchronous development. XμCT-derived measurements of ring width, wood density and biomass production broadly matched dendrometer data, as well as independent regional biomass estimates from the literature. Seasonal onset and cessation of xylogenesis shifted between years, with earlier onset and cessation in the dry year, which was aligned to microtomy data. Our results demonstrate that, in semi diffuse- to ring-porous angiosperms like beech, xylem expansion and secondary wall formation are tightly coupled, even under contrasting water availability, and suggest that dendrometer data can serve as a proxy for intra-seasonal wood biomass production at the stand level. XμCT provides a reliable tool for quantifying xylogenesis and carbon allocation, offering new insights into wood formation dynamics under variable environmental conditions.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148607930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Arbuscular mycorrhiza-upregulated PtPIP1;2 facilitates H2O2 transport to enhance drought tolerance in trifoliate orange.","authors":"Cheng-Zhuo Li, Chong Zhang, Feng-Ling Zheng, Mashael Daghash Alqahtani, Ying-Ning Zou, Qiang-Sheng Wu","doi":"10.1093/treephys/tpag122","DOIUrl":"10.1093/treephys/tpag122","url":null,"abstract":"<p><p>Arbuscular mycorrhizal fungi (AMF) can enhance drought tolerance of host plants; however, the underlying molecular mechanisms remain unclear. Here, PtPIP1;2, a plasma membrane intrinsic protein gene strongly induced by AMF (Funneliformis mosseae (T.H. Nicolson & Gerd.) C. Walker & A. Schüßler) colonization under drought stress, was identified. Subcellular localization confirmed that PtPIP1;2 targets the plasma membrane. To investigate its function, PtPIP1;2-overexpressing (OE) hairy root lines were generated in trifoliate orange (Poncirus trifoliata L. Raf.). Under drought stress, OE plants exhibited better growth performance, greater root biomass and surface area, showed alleviated inhibition of photosynthesis and photosystem II activity, and reduced oxidative damage. Notably, OE plants showed lower root hydrogen peroxide (H2O2) content but significantly enhanced H2O2 efflux. Heterologous expression assays revealed that when expressed alone in Xenopus oocytes, PtPIP1;2 did not confer detectable water permeability; however, it markedly enhanced yeast sensitivity to exogenous H2O2, indicating that PtPIP1;2 contributes to H2O2 transport-associated drought tolerance. Consistently, OE plants maintained a favorable hormonal balance (higher abscisic acid content together with partially restored trans-zeatin, indole-3-acetic acid, and zeatin levels) and showed upregulated expression of stress-responsive genes involved in calcium signaling (PtCDPK10), MAPK cascades (PtMAPK), dehydration protection (PtLEA7), polyamine synthesis (PtADC), and antioxidant enzymes (PtSOD and PtPOD). Collectively, these findings suggest that PtPIP1;2 enhances drought tolerance by facilitating transmembrane H2O2 transport, which is associated with improved reactive oxygen species turnover, a more favorable hormonal balance, and the activation of downstream defense networks. These findings reveal a potential mechanism by which an AMF-inducible aquaporin PtPIP1;2 may act as a redox-regulatory hub to protect plants against drought, along with its potential as a promising target for breeding drought-tolerant citrus rootstocks.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148814188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metabolome signatures during zygotic and somatic embryogenesis of Araucaria angustifolia.","authors":"Bruno Viana Navarro, Jean-Christophe Cocuron, Leandro Francisco de Oliveira, Marina Camara Mattos Martins, Vinícius Jardim, Ana Paula Alonso, Marcos S Buckeridge, Eny I S Floh","doi":"10.1093/treephys/tpag094","DOIUrl":"10.1093/treephys/tpag094","url":null,"abstract":"<p><p>Araucaria angustifolia (Bertol.) Kuntze (Brazilian pine) is a native conifer of high ecological and socioeconomic value and serves as a model for studying zygotic and somatic embryogenesis (SE). Here, we combined biomass composition and targeted metabolomics to compare embryo development in seeds and embryogenic cultures, to identify metabolic features associated with embryogenic competence. We analyzed zygotic embryos at globular, cotyledonal and mature stages, their corresponding megagametophytes and two somatic embryogenic cell lines (Responsive and Blocked) with different embryogenic potential at proliferation and maturation phases. A total of 116 metabolites and biomass components belonging to six major classes (amino acids and their derivatives, fatty acids, sugars and starch, sugar alcohols, phosphorylated compounds and organic acids) were identified. Biomass data showed a marked shift from a globular embryo dominated by insoluble residue to starch- and protein-rich late zygotic stages, whereas somatic lines retained high proportions of insoluble residue and showed limited reserve accumulation. Hierarchical clustering and multivariate discriminant analysis revealed distinct metabolic signatures for zygotic and somatic systems, with amino acids and organic acids emerging as key discriminants. Isocitrate showed the highest variable importance in projection score and was positively correlated with several amino acids and soluble sugars. Co-metabolic network analysis further indicated that amino acid and organic acid classes underwent the strongest topological reorganization, forming increasingly modular and connected networks in zygotic embryos compared with somatic cultures. Together, these results highlight central carbon and nitrogen metabolism as key axes distinguishing zygotic and SE in A. angustifolia, and identify specific metabolites and network features as candidate markers of embryogenic competence.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148397839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Growth patterns and climate sensitivity differ for understory and canopy trees.","authors":"Jakub Kašpar, Jan Krejza, Jan Holík, David Janík, Růžena Janoutová, Kamil Král","doi":"10.1093/treephys/tpag093","DOIUrl":"10.1093/treephys/tpag093","url":null,"abstract":"<p><p>While vertical forest structure is known to influence microclimatic conditions and tree growth, detailed knowledge of differences in seasonal growth dynamics between understory and canopy trees, especially at fine temporal scales, is still lacking. In this study, we compared growth dynamics of five temperate tree species (Picea abies, Fagus sylvatica, Carpinus betulus, Acer campestre, Ulmus laevis) based on sub-daily measurements from automatic band and pivotal dendrometers across four old-growth forests. Hourly growth probabilities were modelled using Generalized Linear Mixed-Effects Models (GLMMs) in relation to climatic conditions and day phases. Understory trees exhibited shorter growing seasons, accumulated fewer growing hours and displayed a less distinct diel growth rhythm than canopy trees. Nonetheless, when growth occurred, their growth rate per growing hour, normalized by stem diameter, was higher. However, overall growth remained constrained, likely because light availability limited the frequency or duration of such favorable periods, preventing consistent utilization of the buffered microclimatic conditions typical of the forest understory. The GLMMs successfully captured growth dynamics in canopy trees but performed poorly for understory trees, indicating lower dependency of their growth patterns on climatic conditions. Overall, our results show that understory tree growth is constrained primarily by limited light availability rather than by atmospheric conditions, leading to fewer growth periods that account for a larger proportion of the annual increment compared with canopy trees.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13477147/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148424436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A river runs through it: intraspecific variability in hotter-drought-related physiological traits across the Mississippi divide in Pinus taeda L.","authors":"Elisabeth Ilinca, Herve Cochard, William M Hammond, Marylou Mantova","doi":"10.1093/treephys/tpag092","DOIUrl":"10.1093/treephys/tpag092","url":null,"abstract":"<p><p>Human activities are intensifying heatwaves and droughts, threatening forest ecosystems worldwide. However, understanding intraspecific variation in physiological traits that confer resistance to hotter drought is critical for predicting tree responses to climate change. In Pinus taeda L., long-term geographic isolation across the Mississippi River Valley after the last glacial maximum has resulted in distinct population genetic structures, likely reflecting historical adaptation to contrasting climatic conditions in western and eastern refugia. However, it remains unclear whether contemporary populations retain meaningful variation in traits that confer tolerance to hotter and drier conditions, such as hydraulic vulnerability and water-use regulation, which are critical for predicting responses to future climate extremes. Here, in a common garden of adult P. taeda trees planted in 2010, we characterized intraspecific variability in 22 physiological traits related to resistance to hotter droughts across 10 provenances originating from either west or east of the Mississippi River Valley. Key traits included xylem vulnerability to embolism, leaf and bark residual conductance, and leaf turgor loss point. We used an integrated indicator, Time to Hydraulic Failure (THF), predicted by a mechanistic hydraulic model, SurEau, to assess how trait combinations contribute to tree resistance to hotter droughts. While we hypothesized that western provenances would be more adapted to hotter drought, we found that THF was lower in western than eastern provenances. The THF values were negatively correlated with residual transpiration and leaf mass per area. These patterns suggest physiological differentiation between populations, although not one strictly determined by drought resistance alone. Overall, our findings demonstrate that intraspecific variation in physiological traits can inform forest management and breeding strategies, underscoring the complex interplay of hydraulic and residual transpiration traits in shaping drought resilience and emphasizing the need to integrate multiple physiological processes when predicting forest responses to climate change.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148388211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Growth and trait covariations across 100 olive (Olea europaea L.) varieties: phenotypic structure depends more on the identity of varieties than on their genetic and geographic origins.","authors":"Siham Wakib, Ahmed El Bakkali, Hayat Zaher, Abdelilah Meddich, Cherkaoui El Modafar, Karim Barkaoui, Eric Garnier","doi":"10.1093/treephys/tpag095","DOIUrl":"10.1093/treephys/tpag095","url":null,"abstract":"<p><p>Understanding how traits covary and influence growth is key to understanding adaptation in perennial species. In the Mediterranean olive tree (Olea europaea L.), both genetic background and geographical origin (GO) may shape trait variability, covariation patterns, and growth strategies, however these relationships remain largely unexplored. We analysed 100 olive varieties, representing four genetic groups and two GOs (North vs South Mediterranean), by measuring 11 morpho-anatomical and physiological traits, and two growth indicators. We combined multivariate analyses, correlation networks and regression models to explore trait covariation and its impact on growth. Our findings show that trait variation was primarily structured at the varietal level, while both genetic groups and geographic origin significantly shaped covariation patterns and functional integration, with southern-origin varieties tending to exhibit thicker and denser leaves. Trait networks revealed a robust coordination between leaf and stem structural traits, with modularity and connectivity varying across groups. The South group exhibited a more modular network, suggesting more constrained trait integration under arid conditions. At both stem and whole-plant levels, growth was positively associated with leaf area. In contrast, leaf dry matter content showed a positive relationship with stem diameter growth but a negative relationship with whole-plant growth, suggesting that different mechanisms underlie short-term stem expansion and long-term cumulative growth. Overall, genetic factors, environmental context and trait coordination jointly structure olive phenotypic diversity. These findings provide a functional framework for guiding the selection and conservation of olive varieties with growth strategies suited to current and future Mediterranean climates.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148430437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Consistent δ13C offsets between whole wood and α-cellulose of Pinus sylvestris confirmed across contrasting forest stand types and a climatic gradient.","authors":"Shebeshe Assefa, Maurizio Ventura, Felipe Bravo, Francesco Giammarchi, Kamil Bielak, Enrico Tomelleri, Camilla Wellstein","doi":"10.1093/treephys/tpag073","DOIUrl":"10.1093/treephys/tpag073","url":null,"abstract":"<p><p>Whole wood can be used as a practical alternative to α-cellulose in tree-ring 13C isotopic (δ13C) analysis. However, the consistency of the relationships between δ13C of whole wood (δ13CW) and α-cellulose (δ13CC) and their climatic sensitivity can vary across contrasting forest stand structures in tree species composition and along an eco-climatic gradient. We assessed whether δ13CW captures inter-annual variation and climatic sensitivity that are comparable to those obtained from δ13CC of Pinus sylvestris L. The study was conducted across three monospecific and two mixed-species forest stands spanning Mediterranean, temperate and continental-temperate climates. Using 145 individual tree rings from 15 trees, we analyzed offset and correlation between δ13CW and δ13CC, centered around two site-specific pointer drought years (1983 and 2014), including the 2 years before and after drought. Bootstrapped correlation and linear mixed-effect models were used to evaluate and compare the climatic signal strength between δ13CW and δ13CC across the study sites and among monospecific and mixed-species forest stands. Across sites and stand species composition types, δ13CW and δ13CC exhibited significantly different δ13C values, with a constant offset of 1.3‰ (±0.13‰ standard deviation). δ13C values were strongly correlated (91-98%) for the two substrates, showing comparable inter-annual variation and similar sensitivity to climatic factors. We conclude that δ13CW appears to be a reliable alternative to δ13CC under our eco-climatic and forest structural conditions. Our results confirm previously reported strong correlations and stable offset between δ13CW and δ13CC in P. sylvestris. By demonstrating this consistency across contrasting stand composition and wide climatic gradients, our study adds empirical support for the use of δ13CW when cellulose extraction is not feasible. δ13CW is a faster, less labor-intensive and more cost-effective alternative method to quantify, based on pointer years, the effects of water stress on tree growth in large-scale spatial dendro-isotopic studies at the level of annual resolution.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148593260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Within-crown leaf variation: a driver of heterogeneous leaf death during drought.","authors":"Vanessa Tonet, Kate M Johnson, Chris M Smith-Martin, Timothy Brodribb","doi":"10.1093/treephys/tpag075","DOIUrl":"10.1093/treephys/tpag075","url":null,"abstract":"<p><p>Drought often causes patchy leaf mortality within tree canopies, yet the mechanisms driving this heterogeneity remain poorly understood. We quantified variation in key leaf hydraulic and structural traits within the crowns of three mature Eucalyptus viminalis Labill. trees and assessed how this variability influences the water potential at which runaway cavitation occurs, and the predicted timing of leaf desiccation. Substantial variation in traits was observed across hierarchical levels, with the largest proportion occurring amongst leaves within branches. While the water potential at 50% loss of xylem water transport capacity (P50) exhibited within-individual variation, variance partitioning showed that much of its total variability occurred between individuals. In contrast, traits such as leaf hydraulic conductance (Kleaf) and minimum stomatal conductance (gmin) varied more strongly at the leaf and branch levels. The sensitivity analysis indicated that P50 had the strongest influence on runaway cavitation when traits were varied independently. However, when incorporating observed within-crown variation (calculated within individual canopies only), multiple traits contributed to variation in runaway cavitation and predicted desiccation timing. Modelled time to leaf death varied widely within canopies, suggesting a staged mortality process during drought. These findings indicate that even moderate within-crown trait variation can strongly influence canopy responses to water deficit.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148151425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}