兴安落叶松叶水力与光合性状的变异性和相关性

Variations and interrelationships of foliar hydraulic and photosynthetic traits for Larix gmelinii

树木叶水力和光合性状的变异性及权衡策略对评估和预测气候变化对树木的存活、生长及分布至关重要。在帽儿山森林生态站27年生兴安落叶松(Larix gmelinii)人工林从山谷至山脊设立一条由5个样地组成的全坡位样带,测量兴安落叶松黎明前叶水势(Ψ_(pre))、基于叶面积和叶质量的水力导度(K_(area)和K_(mass))、抗栓塞能力(P50)、比叶质量(LMA)、净光合速率(A)、叶氮含量(N)等叶水力和光合相关参数,探索其叶性状随立地条件的变异性和相关性。结果表明:不同样地的Ψ_(pre)、K_(area)、K_(mass)、P_(50)、A、LMA和N均存在显著差异(p<0.05),表明叶性状随立地条件变化而表现出显著的种内变异性。Ψ_(pre)和K_(area)或K_(mass)均与P_(50)显著相关(p<0.05),表明兴安落叶松种内存在一定的水力效率与安全权衡关系。A、LMA和N均存在成对相关关系(p<0.05)。然而,水力性状与光合性状之间相关不显著。兴安落叶松响应于立地条件变化而表现出的叶水力和光合性状的可塑性和多重相关性,是该树种的一种生存生长策略。

Aims Variations and potential trade-offs of leaf hydraulic and photosynthetic traits are essential for assessing and predicting the effect of climate change on tree survival, growth and distribution. Our aims were to examine variations and interrelationships of leaf hydraulic and photosynthetic traits in response to changes in site condi- tions for Dahurian larch （Larix gmelinii）--a dominant tree species in Chinese boreal forests. Methods This study was conducted at the Maoershan Forest Ecosystem Research Station. A transect of 27 year-old Dahurian larch plantation was established that consisted of five plots extending from the valley to the ridge of a slope. The predawn leaf water potential （Tpre）, area- and mass-based leaf hydraulic conductance （K^re~ and Km,ss, respectively）, resistance to embolism capacity （Ps0）, leaf mass per area （LMA）, net photosynthetic rate （A）, and leaf nitrogen content （N） were measured in August 2016. Important findings The ~pre, Karca,/（mass, Ps0, A, LMA, and N all varied significantly among the plots （p 〈 0.05）, indicating significant intra-specific variations in these traits in response to the changes in site conditions. The Ps0 was significantly （p 〈 0.05） correlated with Tprc, garea or Kmass, suggesting that a trade-off between hydraulic efficiency and safety exist within the species to some degree. There were significant （p 〈 0.05） pairwise correlations between A, LMA, and N. Nevertheless, there was no significant （p 〈 0.05） correlation between the measured photosynthetic traits and hydraulic traits. We concluded that the intra-specific variations and multiple interrelation- ships of the leaf hydraulic and photosynthetic traits for the larch reflect the plasticity of its leaf traits and strategies of its survival and growth as a result of its acclimation to diverse site conditions.