Wind erosion is an important part of environmental change research and represents a key destabilizing factor in arid and semi-arid ecosystems. The desert-oasis ecotone is an ecological barrier that protects oases from sandstorms. Nitraria tangutorum nebkhas help mitigate the impacts of wind erosion in desert-oasis ecotones. This study analyzed the relationship between vegetation coverage and soil grain size in a desert-oasis ecotone along the southeastern margin of the Tengger Desert. The results showed that the soil grain size distributions for nebkhas consisted primarily of fine, medium and very fine sand. The measured proportion of fine sand increased as vegetation coverage increased. The trailing edge of leeward slope and leading edge of windward slope positions contained higher proportions of coarse-grained material relative to other slope positions. Samples collected 0-5 cm depth contained higher proportions of fine-grained material than those collected at 5-10 cm depth. The average particle size ranges for nebkhas with low, medium, and high vegetation coverage were 1.644-2.430 φ, 1.601-2.911 φ, and 1.752-2.871 φ, respectively. Soil sorting degree was categorized as medium. Skewness values were extremely negative, negative, and positive respectively, and kurtosis levels were medium, narrow and medium, respectively. Samples collected from windward slope positions gave higher mean grain size values than those measured from samples collected along leeward slope and the top positions.

The response of surface radiation and water-heat flux to soil moisture is a critical mechanism in drought, desertification and other effects of climate change. This study analyzed soil moisture data and four-component radiation data during the summers (June, July and August) from 2010 to 2018 in a desert steppe environment of Inner Mongolia. The influence of soil moisture on the radiation flux and water-heat flux under dry, intermediate and wet conditions were quantified through correlation analysis. Radiation and water-heat fluxes showed obvious diurnal changes under different soil moisture conditions. Net longwave radiation and soil heat flux showed the largest differences in diurnal variation followed by net surface radiation, total flux and albedo. Net radiation, net longwave radiation, surface received longwave radiation, soil heat flux and total flux all increased with increasing soil moisture, while surface reflection ability decreased. Soil moisture during wet intervals (16.57-28%) showed a stronger correlation with fluxes than dry and intermediate intervals (9.78-16.46%). This indicates that soil moisture exerts a stronger influence on surface flux under moist conditions. Soil moisture showed a negative correlation with surface reflecting longwave radiation (P<0.01) and a positive correlation with net longwave radiation, net surface radiation and total flux (P<0.01). The research shows that soil moisture interacts with the atmospheric system through its influence on total flux (sensible heat and latent heat) and surface net radiation.