Variation and association of leaf traits for desert plants in the arid area, northwest China

Characterizing variation and association of plant traits is critical for
understanding plant adaptation strategies and community assembly
mechanisms. However, little is known about the leaf trait variations of
desert plants and their association with different life forms. We used
principal component analysis, Pearson's correlation, phylogenetic
independent contrasts, linear mixed model, and variance decomposition to
explore the variation and association of 10 leaf traits in 22 desert
plants in the arid area of northwest China. We found that: (1) the
contribution of interspecific variation to the overall variation was
greater than the intraspecific variation of all the studied leaf traits;
(2) intraspecific and interspecific variation in leaf traits differed
among life forms. Some leaf traits, such as tissue density of shrubs and
specific leaf area of herbs, exhibited greater intraspecific than
interspecific variation, while other traits exhibited the inverse; (3)
desert shrubs corroborate the leaf economic spectrum hypothesis and had a
fast acquisitive resource strategy, but herbs may not conform to this
hypothesis; (4) there were trade‐offs between leaf traits, which were
mediated by phylogeny. Overall, our results suggest that interspecific
variation of leaf traits significantly contributes to the total leaf
traits variation in desert plants. However, intraspecific variation should
not be overlooked. There are contrasts in the resource acquisition
strategies between plants life forms. Our results support understanding of
the mechanisms underlying community assembly in arid regions and suggest
that future works may focus on the variation and association of plant
traits at both intra‐ and interspecific scales.

解析植物性状的变异与关联，对于理解植物适应策略与群落构建机制具有关键意义。
然而，目前针对荒漠植物叶片性状变异及其与不同生活型（Life Forms）的关联研究仍较为匮乏。本研究采用主成分分析（Principal Component Analysis）、皮尔逊相关分析（Pearson's Correlation）、系统发育独立对比（Phylogenetic Independent Contrasts）、线性混合模型（Linear Mixed Model）以及方差分解（Variance Decomposition）等方法，对中国西北干旱区22种荒漠植物的10项叶片性状的变异与关联特征展开探究。
研究结果显示：（1）所有受试叶片性状的种间变异对总变异的贡献均大于种内变异；（2）叶片性状的种内与种间变异因生活型而异：部分性状（如灌木的组织密度（Tissue Density）与草本植物的比叶面积（Specific Leaf Area））的种内变异大于种间变异，其余性状则呈现相反趋势；（3）荒漠灌木符合叶片经济谱假说（Leaf Economic Spectrum Hypothesis），具备快速获取资源的策略，而草本植物可能并不遵循该假说；（4）叶片性状间存在权衡（Trade-offs）关系，且该关系受系统发育介导。
总体而言，本研究结果表明，荒漠植物叶片性状的种间变异对总性状变异具有显著贡献，但种内变异亦不容忽视；不同生活型植物的资源获取策略存在差异。本研究结果有助于理解干旱区群落构建的内在机制，并提示未来研究可同时从种内与种间尺度出发，聚焦植物性状的变异与关联特征。