功能性状与干旱下树木自然更新能力关系的meta分析

A meta analysis of the association between functional trait and tree regeneration capacity under drought

全球气候变化下极端干旱事件频发,对全球生态系统稳定造成了巨大挑战。森林在维持全球生态系统稳定方面发挥着不可替代的作用。由于不同乔木物种对干旱有不同程度的敏感性,特别是在自然更新阶段,不同物种种子产生、种子萌发、幼苗生长都对水分变化存在不同的敏感性,探讨影响种间敏感性差异的机制对预测森林对未来气候变化的响应具有重要意义。目前关于树木成体对干旱的响应已有众多实验性和整合性的定量研究,然而还未见关于树木自然更新对干旱响应的整合性研究。本研究采用meta分析手段,在全球范围内搜集野外观测和控制实验获得的树木种子产量、种子萌发率、幼苗出苗率和幼苗存活率等自然更新过程相关指标,定量评估干旱胁迫对不同物种自然更新的效应强度。结合树木的功能性状(包括叶片面积、叶片厚度、植株最大高度、根系深度、种子大小、比叶面积、气孔导度、P50和叶片水势),发掘不同物种干旱响应差异的潜在解释因子。结果表明,影响干旱胁迫下树木自然更新的功能性状在光合作用、叶片表型和种子大小之间存在相互协调关系,那些能够在降低水分散失的同时保证高光合速率或能够维持较快生长速率的树种将在干旱中保持较强的自我更新能力。本研究为不同树种功能性状对其干旱下自然更新的影响提供了整合性的证据,强调了考虑物种性状信息对全球气候变化下森林保育的重要意义。

More frequent and more extreme drought events under global change have posed severe threats to global ecosystems.Forests play an irreplaceable role in maintaining global ecosystem stability.Because different tree species show varying degrees of drought sensitivity,which is especially true at the early natural regeneration stage,where seed production,germination,and seedling growth of tree species strongly depend on water conditions,it is of profound significance to explore the underlying mechanisms of the intraspecific differences of species in response to drought.While numerous experi‐mental and integrated studies have been conducted for adult tree responses to drought,integrated studies on the natural regeneration of trees are still lacking.In this study,a meta-analysis was conducted by collecting the data of regeneration-related indicators such as seed yield,seed germination,seedling emergence and seedling survival based on field observations and controlled experiments at the global scale.We quantified drought effects on the natural regeneration of different tree species and explored the explanatory potential of plant functional traits[i.e.,leaf area,leaf thickness,plant height,root rooting depth,seed dry mass,specific leaf area(SLA),stomatal conductance,P50,leaf water potential]on the differential drought responses across species.Functional traits affecting natural regeneration of trees under drought stress showed a coordinated relationship among photosynthesis and leaf morphologies.The species that could reduce water loss while maintaining high photosynthetic rate tend to have a stronger regeneration capacity.This study provides integrative evidence of the effects of tree functional traits on natural regeneration under drought stress and highlights the importance of incorporating plant trait information in forest conservation under global climate change.