Uncertainties of Two Methods in Selecting Priority Areas for Protecting Soil Conservation Service at Regional Scale

Soil conservation (SC) is an important ecosystem regulating service. At present, methods for SC mapping to identify priority areas are primarily based on empirical soil erosion models, such as the RUSLE (Revised Universal Soil Loss Equation) based model. However, the parameters of the empirical soil conservation model are based on long-term observations of field experiments at small spatial scales, which are very difficult to obtain and must be simplified when implementing these models at large spatial scales. Such simplification of model parameters may lead to uncertainty in quantifying SC at regional scale. In this study, we have analyzed a new method to map SC in Jiangxi Province of China based on the multiplication of multiple biophysical data. After comparing the spatial-temporal changes of SC from the RUSLE based model and those from the surrogate indicator based method in the study area, the similarities and differences of these methods for identifying SC priority areas were revealed. The result showed that the two methods similarly represented the effects of vegetation coverage and land use types on SC, however, they were significantly different in representing the spatial pattern of SC priority areas and its temporal change. Based on the comparisons, the advantages and drawbacks for both methods were made clear and suggestions were made for the suitable use of the two methods, which may benefit for the research and application of concerning the planning and assessment with SC as key criteria.