Influence of Land Use Change on Litter and Soil C, N, P Stoichiometric Characteristics and Soil Enzyme Activity in Karst Ecosystem, Southwest China

Abstract

In this study, the litter and soil under four typical land use patterns of primary forest, shrub, grassland, and sloping land in Huajiang Karst Gorge in Guanling, Guizhou Province, were used to study the effects of land use change on the carbon(C), nitrogen(N), and phosphorus(P) stoichiometry characteristics of karst plant litter and soil as well as the effects on soil enzyme activities and their driving mechanism in Southwest China. The results showed significant differences in the litter-soil C, N, and P contents and soil enzyme activities among the four land use types. Compared with other regions, the litter and soil showed a pattern of high C, low N, high P and low C, low N, high P, respectively. Urease, sucrose, and amylase showed an order of primary forest > shrub forest > grassland > slope farmland, whereas alkaline phosphatase showed primary forest > shrub forest > slope farmland > grassland. The protection of primary forests should be considered in future ecological construction. The soil nutrients were significantly affected by litter C, N, P, and their ratios, although the soil enzyme activities were not significantly associated with the litter. Redundancy analysis showed that soil enzyme activity had extremely significant correlation with the soil total N (TN), water content (SWC), and C:N ratio (P<0.01) and relatively significant correlation with pH and the N:P ratio (P<0.05). The order of importance was shown to be TN > SWC > C:N > pH > N:P. The research results have significant value for the study of karst rocky desertification and karst ecosystem nutrient cycling.