Spatial environmental heterogeneity may drive functional trait variation in Hydrocotyle vulgaris (Araliaceae), an invasive aquatic plant

Invasive aquatic plants have the potential to threaten ecosystem stability and bio diversity in non-native ranges; it is therefore necessary to prevent and control such invasions. While environmental heterogeneity might drive functional trait variation in plant species across different spatial scales, the drivers of trait variation over a large spatial scale are not well understood for aquatic invasive plants. Understanding functional trait variation across space and potential environmental drivers might improve our understanding of habitable conditions for predicting where an invasive plant species might be found. Here, we studied Hydrocotyle vulgaris (Araliaceae) in Zhejiang Province, China, and propose that environmental spatial heterogeneity might drive functional trait variation of this invasive aquatic plant over a large scale. The investigation was conducted across 99 plots at 7 sites with H. vulgaris. We found significant variation in functional traits over a large scale, and these functional traits were significantly different across a variety of environmental conditions. Specifically, there were significant relationships between environmental factors (i.e. temperature, precipitation, solar radiation, and water vapor pressure) and functional traits, including specific leaf area, interval length, and specific interval length, indicating that spatial environmental heterogeneity might drive the variation in functional traits (especially leaf and clonal traits) of H. vulgaris, over a large spatial scale. Our study thus provides new insights into understanding the invasiveness of H. vulgaris.