Objective To clarify the effects of simulated nitrogen deposition and simulated grazing on the quantitative characteristics and diversity of plant communities in desert grasslands and to explore the changes in the quantitative characteristics and diversity of plant communities in the hope of providing theoretical basis for the scientific management of such desert grasslands.

Methods The warm desert grassland in Yushugou, Urumqi City was taken as the research object and the field survey sampling method was used to determine and analyze the quantitative characteristics and species diversity of plant communities in different nitrogen application gradients (N0: 0 g/m²; N1: 2.5 g/m²; N2: 5.0 g/m²; N3: 10.0 g/m²; N4: 15.0 g/m²; N5: 20.0 g/m²) in grazing and non grazing areas.

Results At the N0 and N1 addition levels, the plant community height in the simulated grazing area was reduced by 15.46% and 20.33% (P<0.05) compared to the control area. Under the N1, N2, and N5 treatments, the plant community coverage in the simulated grazing area was reduced by 25.18%, 23.21%, and 30.00% (P<0.05) compared to the control area; Under the N2 addition level, the Pielou evenness index of plant communities in the simulated grazing area was significantly reduced by 7.83% (P<0.05) compared to the control area; Under the addition levels of N4 and N5, the Simpson dominance index of plant communities in simulated grazing areas significantly decreased by 9.30% and 13.63% compared to the control area (P<0.05), respectively; The important values of Poaceae in simulated pastoral areas significantly increased by 60.89%, 52.34%, and 57.55% (P<0.05) compared to the control area at the N1, N2, and N5 addition levels; Compared with the control area, the important values of legumes in the simulated grazing area were significantly reduced (P<0.05); Under N1, N2, N4, and N5 treatments, the importance values of miscellaneous grasses in the simulated grazing area were significantly reduced by 21.29% to 70.21% (P<0.05) compared to the control area; The important values of Poaceae in simulated grazing areas and control areas were negatively correlated with community diversity (P<0.05); The important values of mixed grass in simulated grazing areas and control areas were positively correlated with community diversity (P<0.05).

Conclusion Simulated grazing significantly increases the important value of Poaceae, enhances its dominant position in temperate desert grasslands under nitrogen deposition background, and enables it to better adapt to changes in temperate desert grasslands under grazing conditions, which is beneficial to the restoration of degraded grasslands.