Landscape changes of alpine grasslands in the Zhari Namco basin of the central-southern Qiangtang Plateau

Abstract

Abstract Context. The Qiangtang Plateau, with its high elevations and cold, dry climate, poses challenges for fieldwork, particularly for ecological research of alpine grassland landscapes at the plant community scale. Objectives. This study aimed to establishand map the distribution patterns of dominant communities in the alpine basin of Zhari Namco. It also investigated the evolution over the past two decades in terms of the number of grasslands, their structural changes, and the fragmentation of habitats. Methods. We quantified the habitat characteristics of dominant plant communities considering topography, hydrology, and fractional vegetation cover. Fifteen landscape indices were selected to examine the characteristics of the grassland changes. Results. The results indicated: (1) the patches of S. purpurea steppe and K. pygmaea meadow were more fragmented compared with the other types. These two types had a decisive impact on the entire grassland landscape; (2) the patch structure of both Carex swamp meadow and C. moorcroftii meadow remained stable, but displayed a different degree of habitat fragmentation as a result of grazing management; and (3) S. purpurea + C. moorcroftii steppe, located in areas with the best hydrothermal conditions, maintained a relatively stable grassland structure with a lighter degree of habitat fragmentation. It is the most suitable grassland resource for grazing in the study region. Conclusions. The present findings provide a reference for exploring the changes in the type and scale of alpine grassland plant communities. It also serves for the rational utilization of alpine grassland resources in the Qiangtang Plateau.