Influence of landscape pattern changes on water conservation capacity: A case study in an arid/semiarid region of China

Abstract

With the accelerating changes of land use/cover caused by natural and human factors, landscape pattern has undergone significant changes. Given the scarcity of water resources and the degradation of ecological functions in arid and semi-arid regions of China, it is necessary to analyze the impact of landscape pattern changes on water conservation. Taking the Wei River Basin (WRB) as the research area, based on water balance equations, FRAGSTATS 4.2 software, and correlation analysis method, this study explored the spatiotemporal distribution characteristics of water conservation and landscape pattern in the WRB from 1990 to 2020, as well as the correlations between the two. The results showed that from 1990 to 2020: (1) the water conservation capacity (WCC) showed no insignificant change trend (P > 0.05) in sub water basins as well as the entire WRB, and it presented a spatial distribution pattern of more in the south and west, and less in the north and east; (2) the landscape diversity and fragmentation of the WRB have increased, and the patch shapes tended to be complex, while connectivity and agglomeration between patches decreased; (3) The WCC had significant negative correlations with the Contagion Index (CONTAG), connectivity index (COHESION), and largest patch index (LPI), while had significant positive correlations with landscape shape index (LSI), Shannon diversity index (SHDI), and separation index (SPLIT), indicating that the increase of landscape fragmentation and diversity was conducive to the improvement of WCC. In the process of ecological landscape planning and optimization, the fragmentation degree of landscape can be appropriately increased. (4) Vegetated grassland, forestland, and farmland were the main sources of WCC, with average WCC values of 81.90, 68.04, and 8.72 mm, respectively. NDVI of the watershed increased significantly (P < 0.01) during the research period and showed a significant positive correlation with WCC, indicating the promoting effect of increasing vegetation coverage on WCC. Relevant results may provide referential information for ecological restoration and optimization of landscape pattern in arid/semiarid regions.