Soil Enzyme Activities of the Typical Degraded Mountainous Ecosystem in the upper Reach of the Lancang River

The soil enzyme activities and the change patterns of each soil enzyme from different soil utilization types in the typical degraded mountainous area of the upper reaches of the Lancang River were studied. The results showed that soil enzyme activities significantly differed from varied land utilization types. The activities of sucrase, urease and protease in the different ecosystems ordered as plantation of Alnus nepalensis > orchard> pure forest of Pinus yunnanensis > plantation of Eucalyptus spp.. The activity of catalase had the order as pure forest of Pinus yunnanensis > plantation of Alnus nepalensis > orchard> plantation of Eucalyptus spp.. It was showed by the correlation analyses that there were significant positive correlations among soil enzyme activity, organic material content and the content of total N in the soil, there were also certain correlations among the varied soil enzyme activities, and all these factors would contribute to the soil fertility development. The comprehensive evaluation on the 6 indexes, i.e., organic material content, total N content, the activities of sucrase, urease, protease and catalase in the soils by the method of factor analysis showed that the integrated soil quality under the plantation of Alnus nepalensis was the best, and then followed by that of orchard, pure forest of Pinus yunnanensis and plantation of Eucalyptus spp..