Spatiotemporal and climate-related variations in soil moisture during the growing season in the hinterland of the Qinghai-Tibet Plateau: An analysis using the temperature-vegetation dryness index

Soil moisture is one of the key factors affecting the ecological capacity and regeneration of alpine grassland in the Qinghai-Tibet Plateau. Using the temperature–vegetation dryness index (TVDI), we analyzed spatiotemporal variation and dynamic trends in soil moisture during the growing season in this area. In order to study the response of soil moisture to climate factors, correlation analysis was used to combine these data with data from meteorological stations in the study area. The results showed that during growing season from 2001 to 2018, the soil was on average humid in the northern part of the hinterland of the Qinghai-Tibet Plateau, while it was arid in the northeast and southwest. The proportions of wet, moist, normal, arid, and dry soil were 1.14%, 29.24%, 37.68%, 30.09%, and 1.85%, respectively. In the past 18 years, the soil in the southern part of the study area showed a significant drying trend, while that in the north and northeast tended to become wetter. Soil moisture decreased in most areas. The northern and northeastern regions of the study area were significantly affected by precipitation, while the southwestern region was significantly affected by temperature.