Abstract

The ecological evolution and relevant factors in semi-arid and arid regions is a research focus on climate changes. One such region, the mountain-oasis-desert coupling system in Xinjiang, China, is sensitive to global climate changes because it has a fragile ecological environment. This study attempted to investigate the temporal-spatial variations of surface soil moisture, vegetation cover and their influencing factors of mountain-oasis-desert coupling system in Xinjiang from 1986 to 2015. The results showed that: (1) The surface soil moisture increased in most of the ecoregions of Xinjiang from 1986 to 2015 whereas the vegetation cover decreased in the same period. (2) The comparison of the correlations between soil moisture content (SMC) and the variables of precipitation and temperature revealed that precipitation is an important supplement source of SMC. The variation characteristics of surface soil moisture are closely related to the dry and wet soil conditions. (3) The comparison of the correlations between the normalized difference vegetation index (NDVI) and the variables of precipitation and temperature revealed that the different responses of vegetation to precipitation were related to the gradually decreased precipitation pattern in the mountain-oasis-desert system. Meanwhile, vegetation was found to be more sensitive to precipitation in deserts and oases and more sensitive to temperature in mountainous regions. In each ecoregion, the variation cycles of SMC and vegetation cover were slightly different, but it was found that SMC is more likely to be affected by temperature and precipitation rather than vegetation cover. Overall, surface soil moisture and vegetation cover products have a great potential to be effectively used in investigating landscape pattern variations, which is very important theoretically and practically for the mountain-desert-oasis system in arid areas.