Cropland-grassland use conversions in the agro-pastoral areas of the Tibetan Plateau: Spatiotemporal pattern and driving mechanisms

Abstract

Cropland-grassland use conversion analysis constitutes crucial research on regional land and global change science, having important implications for regional ecology, food security and the well-being of farmers and herders. However, relevant research is rare, and limited attention has been given to the Tibetan Plateau. Therefore, based on land use raster data, this study utilized the land use conversion matrix method to investigate the spatial and temporal patterns of cropland-grassland conversions during 1990–2020 in the agro-pastoral areas of the Tibetan Plateau.Then this research further identified the key natural geographical and socioeconomic driving forces of cropland-grassland conversions, and examined the mechanisms and spatial heterogeneity of their driving effects by using the geographically weighted regression model. The results showed that cropland-grassland conversions temporally presented the “slow-slow-rapid” changes in 1990–2020 and were spatially clustered in the eastern semipastoral areas. Through mechanisms of ecological equilibrium, resource carrying, population mobility, interest-driven and macroregulation, natural geographical and socioeconomic factors within the cropland-grassland conversion system interacted differently in direction and extent with obvious spatial heterogeneity. Regional increasing rainfall, temperature and topographic relief expanded the extent of cropland use, coupled with the effects of distance to transportation and water sources and increased rural employment, causing widespread and profound land reclamation of grassland-to-cropland, further encouraged by cropland balance policy, while climate change and distance from inhabited settlement and transportation promoted cropland-to-grassland conversion, exacerbated by policies on nature reserve designation and cropland balance, and the fact that rapidly increasing urbanisation in the east accelerated cropland abandonment by diversifying nonfarm employment livelihood strategies. Value added in agriculture and livestock and agricultural machinery inputs tended to restrict cropland-grassland conversions by promoting their internal tapping into intensive and potential use. “Key place-based” and differentiated management policies were proposed to promote sustainable cropland-grassland use conversions and regional development.