荒漠植物功能性状分异与土壤环境异质性之间的关系

Elucidating relationships between plant functional trait variations and soil environmental heterogeneity is a first step towards understanding plant adaptation mechanism and prediction of plant community structure. Heterogeneous distribution of soil environmental factors have strong effects on plant functional traits variations. Although there is ample evidence on the tight links between functional traits variations and soil resource availability, the role played by soil environmental heterogeneity as modulators of such relationship is poorly known, especially in typical desert region of Xinjiang. This project will focus on seventeen traits that incorporate information on desert plant morphological, chemical and physiological functions, quantify intraspecific and interspecific trait variability and their contribution to community functional diversity. Effects of soil environmental heterogeneity on intraspecific and interspecific variations and community trait variations will be analyzed. We will explore the relationships between community functional diversity and soil environmental heterogeneity, identify the role of environmental filtering and interspecific competition in community trait variations by stochastic simulating and testing of functional diversity, and interpret the niche process mechanism of desert plant trait variations under heterogeneous soil environment. This project aims to reveal the rule of desert plant functional trait variation and its driving mechanism of soil heterogeneity, which can help to understand desert plant community assembly, and provide theoretical basis for conservation and utilization of plant resources in arid desert regions.

阐明植物功能性状分异与土壤环境之间的关系是理解植物的环境适应机制与预测群落结构变化的必要基础，但当前在新疆典型荒漠区的相关研究甚少。本项目以植物功能性状分异与土壤环境之间的关系为对象，通过实地调查和实验分析，量化荒漠植物形态、生理和化学功能性状的种内和种间分异对群落功能多样性的贡献；分析不同土壤环境因子异质分布对植物功能性状的种内、种间和群落性状分异的影响；研究群落功能多样性与土壤环境异质性之间的关系，结合群落功能多样性的随机模拟和检验，辨析环境过滤和种间竞争在群落间的作用，探讨异质环境下荒漠植物性状分异形成的生态位机制。研究旨在揭示荒漠植物功能性状分异规律及土壤环境异质性对其影响，有助于理解荒漠植物群落的构建机理，并为干旱荒漠地区植物资源的保护和利用提供理论依据。

基于本项目在艾比湖保护区开展了高(HSW)、低水盐环境(LSW)下植物分布及其多样性特征、荒漠植物功能性状及其多样性与经济谱特征、荒漠植物功能性状的种间、种内变异规律，以及土壤异质性与荒漠植物功能多样性间关系等研究。主要结论如下：.(1) 荒漠植物的分布及多样性与土壤水分、盐分、氮、磷、硫含量密切相关，据此可将保护区植物划分为耐盐碱组、耐干旱组和高磷需求组。.(2) 高水盐环境下(HSW: 16.50±2.89%，12.2±4.93dS/m)群落加权株高、叶绿素含量及叶片碳、钙含量显著高于低水盐环境(LSW: 2.63±2.32%，1.91±1.25dS/m) ；HSW多维功能丰富度、功能离散度显著高于LSW，叶片N、S和Ca的功能分异指数显著高于LSW。.(3) LSW环境下，梭梭性状分布趋于扩散，而骆驼刺性状分布呈收敛趋势。随着土壤水盐下降，荒漠植物叶经济谱总体呈光捕捉元素（C,N,P）与渗透⁃代谢调节元素(S,K,Ca,Na,Mg)间权衡加剧的趋势。 .(4) 叶片C、N、P及其比值的总变异主要由种内变异引起。对于多度加权群落性状，种内和种间变异对HSW、LSW群落C、N变异的贡献相当。两种环境下，群落P及N:P的变异主要由种内变异主导，但在低水盐环境下种内变异的贡献较高水盐环境有所降低。总体来看，HSW群落性状的种内变异贡献低于LSW。种间与种内变异关系由HSW的负相关转变为LSW的正相关。对于非多度加权群落性状，种内变异对大部分群落性状变异的贡献均高于种间变异。种间与种内变异的协作关系在高低水盐环境下均以正相关为主。以上表明艾比湖荒漠植物功能性状的变异主要由种内变异驱动，反映了该地区植物对盐渍和干旱环境的适应。.(5)性状的随机模拟分布表明，株高、叶片N随着土壤水盐降低而趋同，而叶片C、P、SPAD和S均趋异；功能性状总体随着土壤水分、盐分的降低呈现从趋同向趋异的转变趋势，即研究区植物群落是以环境过滤为主导，同时叠加生态位互补的生态位过程构建。.土壤异质性的增加先促进、后抑制功能多样性，可解释艾比湖荒漠植物功能多样性变化的59-83%，说明荒漠地区土壤异质性与植物功能多样性间关系可能是非线性且呈负相关的趋势，反映了该地区群落构建过程可能是多种机制共同作用的结果。