We investigated whether environmental filtering or dispersal-related factors mostly drive helophyte and hydrophyte species richness and community composition in 93 lakes situated in Baikal Siberia. Using partial linear regression and partial redundancy analysis, we studied (1) what are the relative roles of environmental variables, dispersal variables, spatial processes and region identity (i.e., river basins) in explaining variation in the species richness and species composition of helophytes and hydrophytes across 93 Siberian lakes, and (2) what are the differences in the most important explanatory variables driving community variation in helophytes versus hydrophytes? We found that, for both species richness and species composition, environmental variables clearly explained most variation for both plant groups, followed by region identity and dispersal-related variables. Spatial variables were significant only for the species composition of hydrophytes. Nutrient-salinity index, a proxy for habitat trophic-salinity status, was by far the most significant environmental determinant of helophytes and hydrophytes. Our results indicate that environmental factors explained the most variation in both species richness and species composition of helophytes and hydrophytes. Nevertheless, dispersal-related variables (i.e. spatial and dispersal) were also influential but less important than environmental factors. Furthermore, the dispersal-related variables were more important for hydrophytes than for helophytes. Most brackish permanent lakes were mostly located in the steppe biomes of southern Transbaikalia. This characteristic along with the oldest age, the largest distances to both river and settlements and the lowest temperatures in the study region distinguished them from freshwater, drained and more nutrient-rich floodplain lakes.

中文翻译：

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贝加尔湖西伯利亚湖泊大型植物群落的环境决定因素

我们调查了环境过滤或扩散相关因素是否主要驱动位于贝加尔湖西伯利亚的 93 个湖泊中的植物和水生植物物种丰富度和群落组成。使用偏线性回归和偏冗余分析，我们研究了（1）环境变量、扩散变量、空间过程和区域特征（即河流流域）在解释植物物种丰富度和物种组成变化方面的相对作用是什么？ 93 个西伯利亚湖泊中的水生植物，以及 (2) 驱动喜生植物与水生植物群落变异的最重要的解释变量有何不同？我们发现，对于物种丰富度和物种组成，环境变量清楚地解释了两个植物群的大部分变异，其次是区域身份和分散相关的变量。空间变量仅对水生植物的物种组成显着。营养盐度指数是栖息地营养盐度状态的代表，是迄今为止最重要的植物和水生植物的环境决定因素。我们的结果表明，环境因素解释了植物和水生植物物种丰富度和物种组成的最大变化。然而，与扩散相关的变量（即空间和扩散）也有影响，但不如环境因素重要。此外，与散布相关的变量对水生植物比对喜生植物更重要。大多数永久性半咸水湖泊大多位于外贝加尔地区南部的草原生物群落中。这种特征连同最古老的年龄，