Interactive Effects of Precipitation and Nitrogen on Soil Microbial Communities in a Desert Ecosystem

Increased precipitation and nitrogen (N) deposition critically influence ecological processes and stability in desert ecosystems. Studying how the soil microbial community responds to these climatic changes will improve our understanding of the impacts of climate changes on arid environments. Therefore, we conducted a field experiment in the Gurbantunggut Desert, applying phospholipid fatty acid (PLFA) analysis to assess the responses of soil microbial community to climate change. We found that in years with normal precipitation, increased precipitation promoted soil bacterial growth, whereas in drought years, increased N deposition promoted soil bacterial growth more effectively. Although soil microbial diversity did not change significantly overall, it decreased with increasing N deposition. Random forest analysis and linear regression analysis indicated that soil pH and microbial biomass carbon (MBC) were the main drivers for the changes in soil microbial community. Structural equation modeling (SEM) further revealed that increased precipitation increased soil Gram-positive bacteria (G⁺) by raising soil MBC, while decreasing soil Actinomycetes (Act), fungi, and Dark Septate Endophyte (DSE). In contrast, increased N deposition affected soil microbial community by altering soil pH and MBC. Our results highlight the synergistic effects of increased precipitation and N deposition on soil microbial community structure. Further research should pay more attention to the effects of climate changes on soil microbial communities with long-term monitoring to confirm our findings across different ecosystems.