Cheng Zhang, Wenbo Chen, Qiaoqin Liu
The increasing global habitat fragmentation has led to a marked decline in landscape connectivity, posing a severe threat to biodiversity. However, our understanding of how landscape connectivity influences biodiversity, particularly for plant diversity, remains notably limited. Taking the meadow of Poyang Lake as a case and comprehensively considering the ecological processes of water level change and species dispersal, this study firstly applied the landscape pattern metrics and the graph-theoretic connectivity metrics to measure the dynamics of meadow structural connectivity and functional connectivity after identifying the spatial distribution of meadow at different water levels. Then, the effects of meadow connectivity on plant diversity and its scale effects were revealed through the linear regression model (LRM), and the redundancy analysis (RDA) was used to explore the contrasted explanatory of meadow structural connectivity and functional connectivity to plant diversity patterns. The results showed that: (1) Meadow was inundated and divided by water and its shrinkage coexisted with fragmentation when the water level rose. While meadow emerged and spliced and its expansion co-occurred with cohesion when the water level fell. (2) When the water level increased, the shape of patch simplified, the area of patch shrank, the density of patch reduced, the aggregation of patch decreased and the meadow structural connectivity decreased progressively. Meanwhile, the number of components rose, the possibility of connectivity decreased and the meadow functional connectivity reduced dramatically. (3) Higher meadow connectivity not only led to greater plant species richness (α diversity) at the landscape scale but also increased plant community similarity (i.e., low β diversity) at the patch scale. Functional connectivity explains plant diversity patterns better than structural connectivity. This thesis proposes a new perspective of landscape connectivity for biodiversity conservation and landscape pattern optimization in lake areas.