2025-03-01 null null 207(卷), null(期), (null页)
Shrub encroachment and nitrogen (N) deposition have become two critical factors that cause global grassland ecosystems degradation. However, the combined effects of shrub branch shelter and N deposition on soil microbial activity and litter decomposition in grasslands remain obscure. This study adopted four branch shelter levels of 0 % (no shelter), 30 %, 50 % and 70 % as the main plots, and four N additions including 0 g m- 2 a1, 10 g m2 a1, 20 g m2 a1 and 40 g m2 a1 as subplots in a Northwest China desert steppe. Subsequently, soil temperature, soil moisture, pH, N content, activities of C and N cycling-related enzymes, and microbial community structure between 0 and 5 cm were determined post 2 years, and litter decomposition from dominant plants was also determined. The results demonstrated that N additions increased the soil inorganic N content, but decreased soil pH value. However, branch shelters enhanced soil moisture, yet had no effect on soil pH value and N content. As results, N additions inhibited soil N cycling-related enzyme activities, but branch shelters accelerated the activities of the most tested extracellular enzymes. Branch shelters also presented opposite potentials to N additions in affecting soil microbial community structure. Overall, shrub shelters counteracted the negative effects of nitrogen deposition on soil enzyme activity and microbial community structure. Consequently, both branch shelter and N addition promoted litter decomposition. Therefore, branch shelter could be used as feasible measures to restore degraded grasslands caused by shrub encroachment and N deposition in arid and semiarid areas.