Huang Zhenyu, Pan Baozhu, Soininen Janne, Liu Xinyuan, Hou Yiming, Liu Xing
State Key Laboratory of Eco-Hydraulic in Northwest Arid Region of China, Xi'an University of Technology, Xi'an, Shanxi, China.
Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland.
Front Microbiol. 2023 Feb 20;14:1122838. doi: 10.3389/fmicb.2023.1122838. eCollection 2023.
Uncovering the mechanisms underlying phytoplankton community assembly remains a major challenge in freshwater ecology. The roles of environmental filtering and spatial processes in shaping phytoplankton metacommunity in Tibetan floodplain ecosystems under various hydrological conditions are still unclear. Here, multivariate statistics and a null model approach were used to compare the spatiotemporal patterns and assembly processes of phytoplankton communities in the river-oxbow lake system of Tibetan Plateau floodplain between non-flood and flood periods. The results showed that phytoplankton communities had significant seasonal and habitat variations, with the seasonal variations being more remarkable. Phytoplankton density, biomass, and alpha diversity were distinctly lower in the flood than non-flood period. The habitat differences (rivers vs. oxbow lakes) in phytoplankton community were less pronounced during the flood than non-flood period, most likely due to the increased hydrological connectivity. There was a significant distance-decay relationship only in lotic phytoplankton communities, and such relationship was stronger in the non-flood than flood period. Variation partitioning and PER-SIMPER analysis showed that the relative role of environmental filtering and spatial processes affecting phytoplankton assemblages varied across hydrological periods, with environmental filtering dominating in the non-flood period and spatial processes in the flood period. These results suggest that the flow regime plays a key role in balancing environmental and spatial factors in shaping phytoplankton communities. This study contributes to a deeper understanding of ecological phenomena in highland floodplains and provides a theoretical basis for floodplain ecosystem maintenance and ecological health management.
揭示浮游植物群落组装的潜在机制仍然是淡水生态学中的一项重大挑战。在各种水文条件下，环境过滤和空间过程在塑造青藏高原洪泛平原生态系统中浮游植物集合群落方面的作用仍不清楚。在此，我们运用多元统计和空模型方法，比较了青藏高原洪泛平原河-牛轭湖系统中浮游植物群落在非洪水期和洪水期的时空格局及组装过程。结果表明，浮游植物群落具有显著的季节和生境差异，其中季节差异更为明显。洪水期的浮游植物密度、生物量和α多样性明显低于非洪水期。与非洪水期相比，洪水期浮游植物群落的生境差异（河流与牛轭湖）不那么显著，这很可能是由于水文连通性增加所致。仅在流水浮游植物群落中存在显著的距离衰减关系，且这种关系在非洪水期比洪水期更强。变异分解和PER-SIMPER分析表明，影响浮游植物组合的环境过滤和空间过程的相对作用在不同水文时期有所不同，在非洪水期环境过滤起主导作用，而在洪水期空间过程起主导作用。这些结果表明，水流状况在平衡塑造浮游植物群落的环境和空间因素方面起着关键作用。本研究有助于更深入地理解高原洪泛平原的生态现象，并为洪泛平原生态系统维护和生态健康管理提供理论依据。
