Hydrological and microtopographic effects on community ecological characteristics of Carex schmidtii tussock wetland

Hydrology and microtopography are important factors affecting the structure and function of wetland ecosystems and controlling plant community distribution and succession. This study aims to identify the effects of hydrology and microtopography on the structure and function of a wetland plant community. A field survey was conducted in Carex schmidtii tussock wetland. Vegetation was sampled in different microtopographic regions (hummock and interspaces) in three types of tussock wetlands with different hydrological conditions (i.e., droughty, seasonally flooded and long-term flooded). Relative importance value (RIV), species richness, diversity, dominance, as well as community similarity and productivity were calculated. We recorded a total of 52 species of plants, belonging to 21 families and 39 genera, in sample plots. Community ecological characteristics significantly differed under varying hydrological conditions and microtopographic regions. Drought decreased the dominance of the C. schmidtii community but increased the frequency of mesophytes. Species richness and diversity in seasonally and long-term flooded sites were significantly lower than droughty sites, while community dominance and productivity in these areas were significantly higher than in droughty sites. Biodiversity in hummocks was significantly lower than in interspaces, but with higher community dominance and productivity. In droughty sites, C. schmidtii on hummocks lost its dominance, resulting in higher community similarity between hummocks and interspaces. Conversely, in seasonally and long-term flooded sites, C. schmidtii on hummocks was absolutely dominant with RIV of 77.0 ± 2.78% and low community similarity between hummocks and interspaces. Moreover, hummock community structure was more similar to that of the overall community, and C. schmidtii biomass in hummocks was the main source of community productivity, indicating the supporting effects of hummocks on community structure. In conclusion, hydrology and microtopography jointly affect the plant community. Attention should be paid to the protection and maintenance of hummock structure and the dominance of C. schmidtii communities in tussock wetland conservation and management.