Ecological response of ephemeral desert plants and soils to long-term precipitation and nitrogen deposition

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.