The problem of farmland degradation and air pollution caused by wind erosion and particulate matter emissions is serious. Relying on biological soil crust coverage can effectively inhibit the production of wind erosion materials. However, recent studies have discussed the wind erosion and particulate matter emission processes separately and few studies analyzed both, clarifying the changes in the proportion of particulate matter emissions in the total wind erosion. Aiming at the typical farming-pastoral transition zone in the monsoon climate zone, this study used wind tunnels to analyze the wind erosion and particulate matter emissions of algae crusts and moss crusts for different wind speeds and coverage conditions. Results show that the effects of wind speed and coverage on the total wind erosion of biological soil crusts are similar. However, the emission of particulate matter is particularly sensitive to coverage of biological soil crusts. The proportion of particulate matter emissions in wind erosion decreases with increasing wind speed. According to the trend of the proportion with wind speed, the particle emission capacity of moss crust is directly proportional to the particle size and inversely proportional to the coverage. In contrast, the particle emission capacity of algae crust particles is proportional to the particle size, but the relationship with coverage is not regular. The results of this study can improve the knowledge of the relationship between wind erosion and particulate matter emissions and give relevant information for the management of wind erosion and particulate matter emissions.

Seasonal freeze-thawing affects soil water migration and distribution, especially in semi-arid degraded agricultural areas, with important impacts on crop production, and wind erosion. We assessed the distribution and migration of soil water in degraded agricultural areas during freeze-thawing and the effect on plant growth and wind erosion. Soil water content (SWC) and soil temperature (ST) dynamic characteristics at a depth of 0-2 m in the semi-arid agro-pastoral northern China are discussed, using data from November 2018 to May 2019. Changes in water potential energy and pore pressure gradient caused soil water migration to the upper layer, which led to a slight decrease in SWC at each layer before ST dropped to the freezing point. The vertical migration distance of soil water exceeded 70 cm, and the SWC above a depth of 100 cm increased significantly during thawing; the water was mainly obtained from the soil layer below a depth of 120 cm. The initial SWC is the main factor affecting the freeze-thawing process. Our results can partly explain the occurrence of wind erosion in spring and provide a scientific basis for predicting soil water status and developing irrigation and erosion control strategies.

Seasonal freeze-thawing affects soil water migration and distribution, especially in semi-arid degraded agricultural areas, with important impacts on crop production, and wind erosion. We assessed the distribution and migration of soil water in degraded agricultural areas during freeze-thawing and the effect on plant growth and wind erosion. Soil water content (SWC) and soil temperature (ST) dynamic characteristics at a depth of 0-2 m in the semi-arid agro-pastoral northern China are discussed, using data from November 2018 to May 2019. Changes in water potential energy and pore pressure gradient caused soil water migration to the upper layer, which led to a slight decrease in SWC at each layer before ST dropped to the freezing point. The vertical migration distance of soil water exceeded 70 cm, and the SWC above a depth of 100 cm increased significantly during thawing; the water was mainly obtained from the soil layer below a depth of 120 cm. The initial SWC is the main factor affecting the freeze-thawing process. Our results can partly explain the occurrence of wind erosion in spring and provide a scientific basis for predicting soil water status and developing irrigation and erosion control strategies.

Foliar water uptake (FWU) may be a significant way for trees to obtain water; however, studies are lacking on FWU. To determine whether FWU occurs in Platycladus orientalis growing in seasonally arid areas, the process of FWU under soil water content (SWC) of 3.9–6.5%, 6.5–9.1%, 9.1–15.6%, 15.6–20.8%, and 20.8–26.0% and different precipitation gradients (1/mm, 5 mm/h, 10 mm/h, and 15 mm/h) was studied using precipitation with labeled isotopes in simulated rainfall experiments with indoor potted plants. The results showed that FWU occurred in each treatment if the SWC ≤ 21.9% no matter the amount of precipitation. The absorption rate of rainfall by leaves increased with the increase of rainfall intensity, but decreased with the increase of SWC. The greatest rates of FWU were 2.77% and 9.52% of rainfall intensity of 1 mm/h and 15 mm/h, respectively, in the 3.9–6.5% treatment. The precipitation absorbed by the leaves of P. orientalis can be transported to xylem or root system along the water potential gradient of leaves–branches–roots. The precipitation with reverse migration in branches and roots increased with the increase of the water potential gradient of leaves–branches–roots. This study provided insight into water use patterns and water migration within trees.