Spatial and environmental factors contributing to phytoplankton biogeography and biodiversity in mountain ponds across a large geographic area

Exploring phytoplankton biodiversity and biogeographic patterns, and the factors that control them, can help to understand the structure and function of aquatic ecosystems. We selected mountain ponds with minimal anthropogenic disturbance to reveal the biogeographic patterns of phytoplankton and to assess the influence of spatial and environmental factors on phytoplankton biodiversity. On a large regional scale, the phytoplankton communities in the mountain ponds showed geographic patterns—the community composition differed between eastern and western areas. A total of seven phyla and 73 genera were identified. Alpha diversity indices did not significantly correlate with nutrient concentrations. Environmental factors and principal coordinates of neighbour matrices together explained 28.5% of the total variation in phytoplankton community composition in the 41 ponds, with each uniquely explaining 3.0% and 14.4% of the total variation, respectively. Therefore, compared with environmental factors, spatial factors predominantly contributed to the distribution of phytoplankton across the study area. With increasing trophic status, the relative influence of spatial factors decreased, while that of environmental factors increased.