In order to investigate the effects of precipitation and nitrogen deposition on short-lived plants and soil in desert ecosystems, a double-factor experiment with increased nitrogen deposition and precipitation was carried out at the observation point on the southern margin of Gurbantunggut Desert to explore the effects of precipitation and nitrogen deposition on short-lived plant biomass and soil nutrients. The results showed as follows :(1) Compared with the control, the above ground biomass (AGB) and underground biomass (UGB) of short-lived plants were significantly increased by water addition, high nitrogen addition and water + nitrogen treatment. (2) The contents of soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) were significantly increased by water addition, nitrogen addition and water + nitrogen treatment. There was no significant difference in soil pH value among treatment groups. Compared with the control group, the contents of dissolved organic carbon (DOC), nitrate nitrogen (NO3–N), ammonium nitrogen (NH4+-N) and organic matter (SOM) in the other treatment groups were significantly increased, except that the content of ammonium nitrogen (NH4+-N) in the soil was not significantly increased by low nitrogen deposition. (3) AGB was positively correlated with UGB, MBC, MBN and NH4+-N, and was positively correlated with NO3–N (p < 0.05); There was a significant positive correlation between UGB and NO3–N and MBC (p < 0.05), and there was a correlation between soil physicochemical factors. (4) By calculating soil quality index (SQI), group CK had the lowest SQI and group W1N1 had the highest SQI. Therefore, proper water and nitrogen increase can improve the physical and chemical properties of soil, thus contributing to the growth of short-lived desert plants and improving soil quality in this region, which is of great significance for improving the ecological stability of arid desert regions.
The desert ecosystem is an important ecological barrier to prevent desertification and maintain the stability of arid zone ecosystem and regional security. The degree of change and species composition of pioneer species during the early spring recovery of the community can be used as important indicators of regional ecology and to predict subsequent ecological stability in the early spring. Rodents serve as ecological engineers in the ecosystem through their behavior, and they influence the composition of biological communities. In this study, we analyzed the correlations between soil physicochemical properties, community assembly, plant diversity and microbial diversity in the areas disturbed by gerbils (RD) and those not disturbed by gerbils (CK) with ephemeral plants in the arid zone and comprehensively evaluated the soil quality (SQI) and ecosystem sustainability (SI). The results showed the following: (1) soil nutrients within the two different areas were significantly different owing to disturbance, and the biodiversity in the RD was greater than that in the CK, but there was low homogeneity; (2) There were significant differences in plant diversity and microbial diversity within the two different; (3) The correlation analysis of community assembly showed that the niche width of the community in RD was higher and the community composition was more affected by deterministic factors, while that in CK was the opposite; and (4) The analytical results showed that the SI and SQI in the RD were smaller than those in the CK. In conclusion, disturbance by rodents enhances biodiversity in arid areas but detrimental to the long-term development of communities. Therefore, it is important to explore the rational use of disturbance relationships to "complement the strengths and weaknesses," provide a theoretical basis for future reasonable control of disturbance, maintain the ecological development of arid areas, and improve the ecological stability of desert arid regions.
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