Hilly red soil region of Southern China is a main producing area for agriculture, pasture and forestry in China. Due to improper land utilization this region is suffering serious soil erosion. This problem has resulted in emergence of large naked lands called “red desert” and hindrances to local agriculture sustainable development. For this reason, restoring vegetation and improving soil quality become urgently needed in this region. During recent decades, man-made forest restoration was taken as the dominating method to reconstruct the destroyed ecosystem. However, the most effective solution to these naked lands should be nature restoring, on condition that human disturbance stopped. Therefore, exploring the effects of nature restoration on soil quality is very important for reconstruction and management of degraded ecosystems in the hilly red soil region of Southern China.
This study was carried out at the Ecological Experiment Station of Red Soil, Institute of Soil Science, Chinese Academic of Science, which was located in Yujiang County, Jiangxi Province. Four types of erosive degraded red soil (bare land, lichen land, mosses land, grass land), which represent different stages of natural restoring, and an artificially restored woodland (Pinus massonina land) were selected. Soil′s biological properties of these five types of land were determined. Results showed that soil′s biological properties varied during the process of nature restoration on erosive degraded red soil. At the initial stages of restoration, improvement on the soil biological properties by lichen and moss were represented mainly on surface layer soil. Contents of soil microbial biomass C, N, activities of Sucrase and Urease in lichen land were higher than that in bare land in surface soil layer (0-2 cm), without significant difference between them. Moss land presented significantly higher soil microbial biomass C, N and activities of Sucrase, Urease and Acid Phosphatase compared to bare land and lichen land in surface soil layer. There was no significant difference of soil microbial biomass N and activities of Urease and Acid Phosphatase between moss lan and Pinus massonina land. This indicated that moss land was a very important stage for the improvement of degraded red soil quality during nature vegetation restoration process. Resumption of nematode abundances in the bare land, lichen land and mosses land lagged largely to that of soil microbial biomass and enzymes′ activities. Grass land illustrated the highest soil microbial biomass, enzymes′ activities and nematode abundance among the four stages of nature restoration. Biological properties in surface and sub-surface soil layers of grass land were better than pinus massonina land, while in deeper layer the latter presented more effective improvement on soil biological quality. Correlation analysis suggested that resumption of soil microbial biomass was consistent with enzymes′ activities in the process of nature restoration, whereas nematode abundance was discrepant.