Variation and potential influence factors of foliar pH in land-water ecozones of three small plateau lakes

3个小型高原湖泊水陆交错带中植物叶片pH值变异及其潜在影响因素 陆生植物叶片pH值是与植物生理功能和养分利用状况息息相关的重要植物属性，并随植物功能型和环境的变化而变化。然而，水生植物叶片pH值的变异特征及其与陆生植物间的差异性仍不清楚。在3个自然形成的小型高原湖泊的湖滨植物群落中，我们采集植物、土壤和湖水样品，检测了植物叶片pH值与碳、氮含量以及环境条件(水或土壤pH值、土壤水位状况)。从植物功能型和群落两个水平分析了湖滨植物叶pH值沿水分梯度的变化及其潜在影响因素。研究结果表明，不同类型的水生植物，以及水生、沼生和陆生环境中生长的植物的叶pH存在较大差异；浮叶植物叶片pH值(4.21 ± 0.05)显著低于挺水植物(5.71 ± 0.07)和沉水植物(5.82 ± 0.06)；水生草本植物叶片pH值(5.43 ± 0.10)显著低于沼生草本植物(6.12 ± 0.07)和陆生草本植物(5.74 ± 0.05)；陆生草本植物叶片pH值显著高于木本植物。植物功能群间叶片pH值的变异可能与叶片的结构、光利用特性和养分特性有关。群落水平的结果与植物功能型水平相一致：水生群落叶片pH值显著低于陆生群落。群落水平叶片pH值可能主要受物种组成、水分条件和环境pH值的影响。本研究首次探索了水生植物的pH值，并且在景观尺度上对比了不同功能型植物的叶片pH值，为深入探索植物pH值变异机制以及其在水生和湿地生态系统中的生态意义提供参考。     

Geographic patterns and environmental correlates of taxonomic and phylogenetic diversity of aquatic plants in China

Studies on large-scale geographic patterns of aquatic plant diversity can promote research on the generality of macroecological patterns in different ecosystems. Here, we compiled a checklist of 889 aquatic angiosperms in China, including 738 helophytes (emergent and marshy plants) and 151 hydrophytes (submerged, free-floating, and floating-leaved plants). We explore the geographic patterns and environmental correlates of aquatic plant diversity based on six metrics including species richness (SR), weighted endemism (WE), phylogenetic diversity (PD), phylogenetic endemism (PE), the standardized effect size of phylogenetic diversity (PDses), and the standardized effect size of mean phylogenetic distance (MPDses). Our results show that the diversity of aquatic plants in China is extremely uneven, with high diversity in southeastern China and low diversity in northwestern China, and the geographic patterns of taxonomic and PD are generally consistent. The pattern of helophytes differs from that of hydrophytes. Notably, the wavy-shaped pattern of aquatic plant diversity (especially SR and PD for hydrophytes) across the latitude observed in this study is not consistent with those previously observed for aquatic plants in other continents. Climatic variables and water environmental variables are the main drivers of aquatic plant diversity in China; however, the effects of individual variables differ between helophytes and hydrophytes. Water environmental variables have a greater impact on PDses and MPDses of hydrophytes than those of helophytes. Overall, our work provides insight into understanding the large-scale patterns of aquatic plant diversity and is a critical addition to previous studies on the macroecological pattern of terrestrial organisms.