Measuring Dynamic Changes in the Spatial Pattern and Connectivity of Surface Waters Based on Landscape and Graph Metrics: A Case Study of Henan Province in Central China

Connectivity Index-Based Identification of Priority Area of River Protected Areas in Sichuan Province, Southwest China

Identification of the priority area is of great significance for the rational layout of river protected areas (RPAs), and it also poses new challenges for protected areas’ (PAs) construction. This study started with the characteristics of RPAs and chose China’s Sichuan Province as the case for the present study, based on its characteristics of biodiversity conservation value and other characteristic elements. The study selected the river dendritic connectivity index and the other four indicators adding them according to different weights to calculate the comprehensive protected value (CPV) area. Finally, the existing PA distributions within the CPV were compared, and the priority conservation area was identified. The main conclusions are as follows: the total area of high-value areas is about 175,068 km2, accounting for 36.02% of the province and concentrated in the high mountain plateaus of the northwest and the southwest mountain region; the existing PAs are 131,687 km2 in sized, covering only 25.08% of the high-value areas of CPV. In other words, 74.92% of the high-value areas still have not been effectively protected, and the construction of RPAs is relatively lagging in these areas; the total area of priority conservation areas (PCAs) is 131,162 km2, accounting for about 26.99% of the province. The total length of the reach in the PCAs is about 9190.72 km, which is approximately 26.84% of the length of the province’s alternative reaches. The research can provide a scientific basis for the optimization and integration of nature protected areas and land space planning.

Implication of Buffer Zones Delineation Considering the Landscape Connectivity and Influencing Patch Structural Factors in Nature Reserves

Since habitat fragmentation results in species losses worldwide, considering the influence of buffer zones on the maintenance of connectivity provides a new perspective for buffer delimitation. In our study, the implications of buffer zones around nature reserves were studied at four sites in Fuzhou from the perspective of landscape connectivity based on a distance threshold of 1 km. We applied Graph-based connectivity indices at the landscape level and patch level to reveal the overall connectivity and patterns of change in patch importance for maintaining connectivity with various buffer zones. Based on the results of these analyses, we showed the relationship between structural factors and changes in patch importance by Spearman correlation analysis and redundancy analysis. The results indicate that in the sites with smaller habitat proportion (HP), the connectivity is relatively lower, and the changes in patch importance will be greater when the buffer zone increases. Different buffer zone sizes are suggested in four sites to maximize its benefits. Relatively small patches with high shape complexity and close proximity to patches outside the boundary contribute greatly to connectivity by acting as stepping stones.