Wind and sand control features are important tools for limiting desertification. Sand barriers are one of the oldest engineering measures used to reduce wind-sand hazards. Their efficacy and exact mechanism by which they work has remained a topic of scientific debate however. Sediment grain-size distributions can help constrain their utility and function. This research analyzed sediment grain size distributions in samples collected from areas around six different types of sand barriers installed along the southeastern margin of the Tengger Desert. Results were compared with sediment from a bare dune area (no barriers) used as a control. The barrier area samples contained high proportions of coarse sand and relatively low proportions of silty sand and very fine sand. Fine and medium sand were present but clay was not. The lower proportions of fine sand and higher proportions of coarse sand relative to bare dunes documented an effective reduction in aeolian transport by the barriers. Samples from the barrier areas also showed poorer sorting relative to bare dune areas. This appeared as lower kurtosis values and wider frequency distribution curves relative to those measured from bare dunes samples. The wider cumulative frequency curves for samples from the barrier areas likely reflects the higher proportion of coarse-grained material. The Straw/1.5 and PLA/1 barrier types hosted greater sediment accumulation than that observed for the other barrier types (Straw/1, PLA/1.5, Mixed/1 and Mixed/1.5). Sediment grain size distributions showed that the base and middle slope areas of the dune experienced deposition, while the top of the dunes experienced erosion. The Straw/1 barrier (straw installed as a 1 × 1 m grid) performed best in terms of installation costs and protective effects for the study area. This study demonstrates how sediment grain size distributions can be used as quantitative proxies for sand barrier performance in reducing desertification.

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.