Effect of ecological engineering projects on ecosystem services in a karst region: A case study of northwest Guangxi, China

Ecological efficiencies of rocky desertification control measures at the regional scale remain unclear. It is urgent and challenging to determine the influences of ecological engineering on the variations of ecosystem services, and to evaluate the ecological benefit of rocky desertification control measures. In this study, variations of three kinds of ecosystem services (water regulation, soil conservation, and carbon sequestration) were analysed in a typical karst region of Northwest Guangxi China during the period from 2000 to 2010. The relative importance of the main factors that influence these three ecosystem services were analysed using radial basis function network, Kaiser–Meyer–Olkin (KMO), and principal component analysis. The results showed that over half of the study area has experienced an increase in water regulation (50.39%) and soil conservation (58.53%), and approximately 28.24% of the study region has undergone increased carbon sequestration. Environmental factors had a substantial impact on the ecosystem services, and the order of relative importance was as follows: geology > soil > vegetation > temperature > precipitation. Anthropogenic activities have played an important role in the changes to the ecosystem services. In addition to the significant conversion of other land types to woodland (approximately 46.80% of the total transfer area), the vegetation species, shape, and fraction, which are greatly influenced by human activities, contributed 79.05% to the variance. This resulted in a high KMO value of 0.912 (>0.9, represents very suitable), and the Bartlett test was significant (Sig. 0.00). These results showed that although natural environmental factors remained basic influences on the pattern of ecosystem services, anthropogenic activities of ecological engineering projects also had important and positive influences on the ecosystem services. This study also indicated that satellite images and new methods should be applied to deal with the relative lack of existing datasets.