Global insights into the effects of forest thinning on soil, microbial, and enzyme C–N–P stoichiometry and microbial nutrient limitation

Thinning plays an important role in regulating stand density and improving interspecific relationships. In this study, we examined the effects of thinning on soil, microbial, and enzyme C–N–P stoichiometry by integrating 1186 pairwise observations in different forest types (coniferous, broadleaf, and mixed), recovery times (<5, 5–10, and >10 years), thinning intensities (light, moderate, and heavy), and relative humidity indices (integrate the combined effects of background climate: <30, 30–50, and >50). Thinning significantly increased the C:P ratio in the soil (4.3%), microbial (10.8%), and enzyme (5.3%), and the N:P ratio in the soil (3.6%) and enzyme (12.8%). However, thinning decreased the C:N ratio in microbial (5.3%) and enzyme (16.3%) and the vector angle (1.2%). Thinning mainly affected the microbial C:N ratio in coniferous and mixed forests. The soil C:N, microbial C:P, and N:P ratios decreased, whereas the vector angle increased with recovery time. The enzyme C:N ratio decreased, whereas the enzyme N:P ratio increased with thinning intensity. The soil N:P ratio, enzyme N:P ratio, and vector angle increased with increasing relative humidity index. The results highlighted that the soil nutrient cycling process, microbial activity, and C–N–P stoichiometry were significantly affected by thinning. Recovery time, thinning intensity, and background climate were important factors regulating these changes.