Spatial characteristics of soil potassium in the early stage of vegetation restoration and influencing factors in southwest China's karst region

The study established experimental transects in undisturbed areas of the Caohai Nature Reserve in Weining, Guizhou Province. The study aims to examine complete successional transects in different landscapes: non-karst, karst, and vegetation restoration, using the spatiotemporal substitution method. It analyzes the distribution patterns of Total potassium (TK) and Avail potassium (AK) in the soil and employs a Generalized Linear Mixed Model (GLMM) to investigate the effects of geomorphology, soil aggregates, and their interactions on the changes in soil potassium(K) elements. Furthermore, it explores the synergistic effects of K cycling during the vegetation restoration process in karst soils. The findings indicated that: (1) In karst areas, the overall TK content was higher than in non-karst areas, while the AK content in the topsoil was higher in non-karst areas. The TK content in the karst areas tended to approach that of the vegetation restoration zone. (2) After restoration, the dominant plants changed from Gramineae to Gramineae + Asteraceae, and the vegetation richness increased, thereby improving the soil fertility and potassium fixation capacity. (3) The GLMM showed that the karst landscape had a significant effect on the TK and AK contents of surface soil. In the early stage of vegetation restoration, the joint effect of soil and vegetation affected the TK and AK contents in soil.