Soil enzyme activities in different re-vegetation stages on sloping-land with purple soils in Hengyang of Hunan Province,  China

By using the spatial series to replace time series, four typical sampling plots, grassplot(GT), frutex and grassplot(FG), frutex(FX), and arbor and frutex(AF), were selected to explore the relationships among the soil enzyme activities, nutrients and microbes. The four communities on slopingland with purple soils were similar and typical, and denoted four different successive stages in Hengyang of Hunan Province, Southcentral China. The results showed that the activities of soil URE(Urease), PPO(Polyphenol oxidase), INV(Invertase) and CAT(Catalase) are significantly increased from GT to AF, and these activities are decreased with the increase of soil layer depth in every re-vegetation stages. The URE activity is significantly and positively correlated with the PPO, INV and CAT activities, and the INV activity is very, significantly and positively correlated with the URE and PPO activities. The soil nutrients contents such as SOC(Soil organic C), TN(Total N) and AN(Available N) are increased with the succession of re-vegetation, while soil pH values are decreased. The URE activity is very, significantly and positively correlated with the SOC, TN and AN contents and is significantly and negatively correlated with soil pH. The PPO activity is very, significantly and positively correlated with the SOC and AN contents, is significantly and positively correlated with the TN, AP(Available P) and AK(Available K) contents, and is significantly and negatively correlated with soil pH value. The INV activity is significantly and positively correlated with the SOC, TN, AN, AP and AK contents. The numbers of bacteria are the highest in the four revegetation stages, with revegetation succession process, the average number of bacteria is in the following order: AF＞FX＞FG＞GT(P0.05), the order for average fungi count is: FG＞GT＞FX＞AF(P0.05), and for the actinomycetes is: GT＞FX＞FG＞AF(P0.05). Principal component analysis shows that the URE and PPO can be regarded as indexes to assess soil quality in slopingland with purple soils in Hengyang. This study, to some degree, enriches and broadens the vegetation ecology and restoration ecology of this area and provides important theoretical basis for ecosystem restoration and reconstruction in slopingland with purple soils in Hengyang of Hunan Province, Southcentral China.