Dynamic simulation of the grassland connectivity and the effects of landscape pattern in China's Poyang Lake from the integrated perspective of habitat and biology

Analysing the dynamics of landscape connectivity is of great significance for biodiversity conservation, but the scientific expression of ecological processes and the depth of coupling landscape pattern and ecological process requires to be strengthened. Taking the grassland of Poyang Lake as a case, based on the integrated perspective of habitat and biology, and comprehensively considering the ecological process of water level change and species dispersal, this study firstly analysed the changes of functional connectivity of grassland with different water levels and dispersal distances by using the graph-based connectivity indices. Then, landscape pattern indices were applied to analyse the dynamics of landscape pattern of grassland and further study the effects of landscape pattern on landscape functional connectivity. The results showed as follows: (1) From the perspective of habitat, the functional connectivity of grassland has progressively decreased with the increase of water level. From the perspective of ecology, the species dispersal distance had an absolutely positive impact on landscape functional connectivity. With the increase of dispersal distance, the functional connectivity of grassland increased significantly. (2) The dynamics of landscape pattern of grassland showed that with the increase of water level, the patch area shrank, the patch shape tended to be simple, the patch density decreased and the patch fragmentation aggravated. (3) The correlation results between landscape pattern and functional connectivity indicated that flux index (F) had a significant positive relationship with patch density (PD), edge density (ED), probability of connectivity (PC) had a strong significant positive relationship with largest patch index (LPI), COHESION and number of components (NC) had a negative relationship with LPI, ED, COHESION. This study provides theoretical guidance for the protection and management of grassland in Poyang Lake.