An appraisal-analyze method for SWC function of forest in Simian Mountain, China

Soil erosion is one of the biggest environmental problems. It is urgently needed to understand soil and water conservation capacity of different plantation types so that the best plantation type can be determined. In Qinjiagou watershed of Simian Mountain, Chongqing City, 18 indices were selected from canopy layer, litter layer, soil layer and topography to evaluate the soil and water conservation capacities of four common plantation types by ideal point method. Results indicated that the broadleaf plantation of robur (Lithocrpus glabra) and Chinese gugertree (Schima superba) (LS) has the biggest soil and water conservation capacity. The rank of three other plantation types from big to small is the mixed broadleaf plantation of sweetgum (Liguidambar formosana), Chinese gugertree and camphor tree (Cinnamomum camphora) (LSC), the mixed broadleaf-conifer plantation of Chinese fir (Cunninghamia lanceolata), Masson pine (Pinus massoniana) and Chinese gugertree (CPS), and the mixed Pine plantation of Chinese fir and Masson pine (CP). Under the same climate and topographical condition, the broadleaf plantation has better soil and water conservation capacity than the conifer plantation. Sensitivity analysis showed that the three most sensitive indices are soil non-capillary porosity, soil aggregation, and soil initial infiltration rate. The litter amount and soil properties are the most important indicators of soil and water conservation capacity of plantations. Therefore, suitable measurements such as deep tillage should be taken to improve the properties of soil under different plantations.   Key words: Ideal point method, soil erosion, soil and water conservation, soil properties, sensitivity analysis.