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<p>Tree mortality is a key process shaping species diversity and carbon dynamics during natural regeneration. Understanding how intrinsic functional traits interact with environmental drivers to modulate mortality risk is essential for predicting forest trajectories. Here, we evaluated how xylem anatomical traits related to water transport and tree size influence the survival dynamics of biomass-dominant tree species in an eastern Amazonian secondary forest, and whether climatic water‐deficit variables modulate these relationships over time. We applied Cox proportional hazards models with time‐dependent effects to long‐term census data, incorporating species‐level wood density (WD), vessel grouping (VG), specific hydraulic conductivity (Ks) and individual diameter at breast height (DBH). Functional differentiation between species in the functional space across species was assessed using a principal component analysis (PCA) associated with a trait probability density (TPD) framework. Also, we stratified models by census period and related baseline cumulative hazard estimates to maximum cumulative water deficit (MCWD) and vapour pressure deficit (VPD). Higher WD and higher VG were associated with a progressive reduction in mortality risk through time, whereas higher Ks showed a positive and time‐independent association with mortality risk, suggesting that species with greater hydraulic efficiency may experience higher vulnerability to mortality. Larger trees also showed lower mortality risk. Functional space analyses revealed substantial overlap among species, indicating a continuum of strategies rather than discrete functional groups. Species associated with lower mortality risk occupied different regions of the functional space, suggesting that alternative combinations of anatomical traits and tree size may contribute to survival through distinct functional pathways. We found no significant direct relationship between baseline cumulative hazard and climatic water‐deficit variables (MCWD and VPD), suggesting that climate effects may operate indirectly or through delayed demographic responses rather than as immediate drivers of mortality. Together, our results highlight the importance of coordinated variation in xylem traits and tree size for understanding mortality dynamics in secondary Amazonian forests.</p> Graphical Abstract <p></p>

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Xylem anatomical traits and size shape time-dependent survival patterns of tree species in an Amazonian secondary forest

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月7日

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  • Beatriz Vitória Barbosa,
  • Fernando Elias,
  • Luane Botelho,
  • Anthony Barbosa,
  • Rodrigo Oliveira do Nascimento,
  • Jos Barlow,
  • Joice Nunes Ferreira,
  • Grazielle Sales Teodoro

摘要

Tree mortality is a key process shaping species diversity and carbon dynamics during natural regeneration. Understanding how intrinsic functional traits interact with environmental drivers to modulate mortality risk is essential for predicting forest trajectories. Here, we evaluated how xylem anatomical traits related to water transport and tree size influence the survival dynamics of biomass-dominant tree species in an eastern Amazonian secondary forest, and whether climatic water‐deficit variables modulate these relationships over time. We applied Cox proportional hazards models with time‐dependent effects to long‐term census data, incorporating species‐level wood density (WD), vessel grouping (VG), specific hydraulic conductivity (Ks) and individual diameter at breast height (DBH). Functional differentiation between species in the functional space across species was assessed using a principal component analysis (PCA) associated with a trait probability density (TPD) framework. Also, we stratified models by census period and related baseline cumulative hazard estimates to maximum cumulative water deficit (MCWD) and vapour pressure deficit (VPD). Higher WD and higher VG were associated with a progressive reduction in mortality risk through time, whereas higher Ks showed a positive and time‐independent association with mortality risk, suggesting that species with greater hydraulic efficiency may experience higher vulnerability to mortality. Larger trees also showed lower mortality risk. Functional space analyses revealed substantial overlap among species, indicating a continuum of strategies rather than discrete functional groups. Species associated with lower mortality risk occupied different regions of the functional space, suggesting that alternative combinations of anatomical traits and tree size may contribute to survival through distinct functional pathways. We found no significant direct relationship between baseline cumulative hazard and climatic water‐deficit variables (MCWD and VPD), suggesting that climate effects may operate indirectly or through delayed demographic responses rather than as immediate drivers of mortality. Together, our results highlight the importance of coordinated variation in xylem traits and tree size for understanding mortality dynamics in secondary Amazonian forests.

Graphical Abstract