Effects of acid mine drainage and sediment contamination on soil bacterial communities, interaction patterns, and functions in alkaline desert grassland.

Acid mine drainage and sediments (AMD-Sed) contamination pose serious ecological and environmental problems. This study investigated the geochemical parameters and bacterial communities in the sediment layer (A) and buried soil layer (B) of desert grassland contaminated with AMD-Sed and compared them to an uncontaminated control soil layer (CK). The results showed that soil pH was significantly lower and iron, sulfur, and electroconductivity levels were significantly higher in the B layer compared to CK. A and B were dominated by Proteobacteria and Actinobacteriota, while CK was dominated by Firmicutes and Bacteroidota. The pH, Fe, S, and potentially toxic elements (PTEs) gradients were key influences on bacterial community variability, with AMD contamination characterization factors (pH, Fe, and S) explaining 48.6 % of bacterial community variation. A bacterial co-occurrence network analysis showed that AMD-Sed contamination significantly affected topological properties, reduced network complexity and stability, and increased the vulnerability of desert grassland soil ecosystems. In addition, AMD-Sed contamination reduced C/N-cycle functioning in B, but increased S-cycle functioning. The results highlight the effects of AMD-Sed contamination on soil bacterial communities and ecological functions in desert grassland and provide a reference basis for the management and restoration of desert grassland ecosystems in their later stages.

Identifying the natural reserve area of Cistanche salsa under the effects of multiple host plants and climate change conditions using a maximum entropy model in Xinjiang, China.

Cistanche salsa (C. A. Mey.) G. Beck, a holoparasitic desert medicine plant with multiple hosts, is regarded as a potential future desert economic plant. However, as a result of excessive exploitation and poaching, its wild resources have become scarce. Thus, before developing its desert economic value, this plant has to be protected, and the identification of its natural reserve is currently the top priority. However, in previous nature reserve prediction studies, the influence of host plants has been overlooked, particularly in holoparasitic plants with multiple hosts. In this study, we sought to identify the conservation areas of wild C. salsa by considering multiple host-plant interactions and climate change conditions using the MaxEnt model. Additionally, a Principal Component Analysis (PCA) was used to reduce the autocorrelation between environmental variables. The effects of the natural distribution of the host plants in terms of natural distribution from the perspective of niche similarities and extrapolation detection were considered by filtering the most influential hosts: Krascheninnikovia ceratoides (Linnaeus), Gueldenstaedt, and Nitraria sibirica Pall. Additionally, the change trends in these hosts based on climate change conditions combined with the change trends in C. salsa were used to identify a core protection area of 126483.5 km2. In this article, we corrected and tried to avoid some of the common mistakes found in species distribution models based on the findings of previous research and fully considered the effects of host plants for multiple-host holoparasitic plants to provide a new perspective on the prediction of holoparasitic plants and to provide scientific zoning for biodiversity conservation in desert ecosystems. This research will hopefully serve as a significant reference for decision-makers.

Characteristics of moisture and salinity of soil in Taklimakan Desert, China.

The Taklimakan desert is known as the largest dunefield in China and also as the world's second largest shifting sand desert. The Tarim Desert Highway, which is the first highway to cross the Taklimakan desert, was built for the purpose of oil and gas resources extraction in the Tarim area, as well as for the development of the southern area of the Xinjiang Uygur Autonomous Region. Shelterbelts have been planted along the highway to prevent shifting sand from burying the road. This paper analyzes the variations of moisture and salinity of the unirrigated desert soil under natural conditions in the center of Taklimakan Desert. A number of important findings indicating the moisture and salinity of the soil at capillary saturation zone were determined by the groundwater and related to the evaporation on the top. Salinity could be affected by vegetation, which was different from moisture in the soil. Meanwhile, clay layer played an important role in water preservation in the soil, which was also beneficial to the accumulation of salinity in soil. Compared with clay layer, vegetation was a decisive factor for the gathering of salinity. The findings were significant for reasonable adjustment of irrigation in the shelterbelts for the further development of the Tarim Desert Highway.

[Relationships of soil microbial biomass with soil environmental factors in Tarim Desert highway shelter-forest].

By using correlation analysis, this paper studied the relationships of soil microbial quantity and biomass with soil physical and chemical factors and enzyme activities in highway shelter-forests of Tarim Desert, aimed to approach the interactions between microbes and environmental factors in aeolian sandy soil of extremely arid area. The results showed that soil microbial quantity and biomass in the shelter-forests had an increasing trend with the decrease of soil bulk density and particle size (R < -0.84) and the increase of soil moisture content and porosity (R > 0.85), with the correlation between soil microbial biomass and soil bulk density as the key. Soil microbial quantity and biomass were positively correlated with soil nutrient contents, mainly caused by the correlations of soil actinomycetes and microbial biomass C and P with soil available nutrients. Greater differences (R = 0.51-0.91) were observed in the correlations of soil enzyme activities with soil microbial quantity and biomass, which was mainly determined by the correlations of soil invertase and phosphatase activities with soil actinomycetes and microbial biomass C. The increase of soil salt content was not favorable to the accumulation of soil microbial biomass (R < -0.71), and there was a higher positive correlation (R > 0.63) between soil microbial amount and biomass. In practice, good soil condition should be established in the forestlands of arid area for the development of soil microbes and the promotion of soil matter cycling.