Abstract
Understanding biodiversity is essential for preserving the stability of river ecosystems. However, the impact of landscape configurations and seasonal variations on biodiversity within undammed river ecosystems remains unexplored. Therefore, we selected the Chishui River-a naturally flowing tributary of the upper Yangtze River-for a survey of periphytic algae. The present study focuses on the seasonal fluctuations in the β-diversity of periphytic algae within the Chishui River and its correlation with the surrounding landscape patterns. Our findings indicate that there is a substantial influence of seasonal variations on the community structure and β-diversity of these algae within the Chishui River ecosystem. Concurrently, we observed that the turnover component predominantly contributes to β-diversity. In light of these findings, we recommend that conservation measures be implemented across the entire Chishui River basin to safeguard the regional biodiversity. Redundancy analysis elucidated that water temperature, conductivity, and pH were the primary environmental drivers shaping the structure of periphytic algal communities. Furthermore, additional analyses using a random forest model indicated that landscape fragmentation and complexity were key determinants of β-diversity in algal communities. Notably, the number of landscape patches was strongly correlated with the β-diversity of periphytic algae. It is important to highlight that maintaining an optimal balance between the number of patches and their size is crucial for enhancing the ecosystem's capacity to preserve biodiversity. In summary, our findings provide insights into the interplay between biodiversity and land-use practices within complex riverine environments, thereby offering a scientific foundation for the conservation and management of these ecosystems.