Responses of Soil C, N, and P Stoichiometrical Characteristics, Enzyme Activities and Microbes to Land Use Changes in Southwest China Karst

Abstract

The present study aim is to elucidate the effect and influencing mechanism of land use change on soil C, N, and P stoichiometric characteristics, soil enzyme activity and the microbial community in the karst ecosystem of southwest China. The three typical successive evolution land use types of original forest land, slope farmland and shrub-grassland were selected as the study objects in the present study. Additionally, the change in the laws and relationships of soil, the C, N, and P stoichiometric characteristics, the five soil enzyme activities of urease, sucrose, alkaline phosphatase, amylase and protease, and soil microbial community during the land use evolution process were studied. Results showed that (1) during the evolution process of the three land use types, soil C, N, and P stoichiometric characteristics, enzyme activities and microbial PLFAs (phospholipid fatty acids) varied significantly or extremely significantly; (2) in the three land use types studied, there were significant or extremely significant correlations between soil C, N, and P stoichiometric characteristics, enzyme activities and microbial PLFAs; (3) the ecological project of returning farmland to woodland had remarkable ecological effects on increasing soil C and N sink, repairing soil microbial community and improving soil quality; (4) artificial afforestation should be used as the most important and preferential measure for karst vegetation restoration and reconstruction. The present results not only provided scientific bases for land sustainable utilization, vegetation restoration and reconstruction, but also had important value in reducing the release and increasing the sequestration of soil C and N in karst ecosystems of Southwest China.