Ecosystem service value responses to ecological control in Karst region— A case study of Huajiang Gorge Demonstration Area of Rocky Desertification Control in Guizhou

To reveal responses of ecosystem service value to Karst rocky desertification control is important for understanding characteristics and driving factors of ecosystem service value changes in Karst area under environment management. The results are also important for policy making of the subsequent eco-management. In this paper, Huajiang Gorge Demonstration Area of the Rocky Desertification Control Project in Guizhou Province was investigated for the ecosystem service values at the early (from 2000 to 2005) and later (from 2005 to 2010) periods of ecological control project. Values of five ecosystem services, product supply, soil conservation, carbon fixation and oxygen release, water conservation, soil fertility, were calculated with physical amount and value amount calculation methods based on field measurement and survey data. During Rocky Desertification Control Project period from 2000 to 2010, the ecosystem types changed at 14.29 hm² area, accounting for 27.7% of the total area. Areas of stand, shrub increased, while area of cultivated land and bare rock and waste slope decreased. From 2000 to 2005, ecosystem types converted in 11.83 hm² area, accounting for 22.9% of the total area, mainly happening in returning farmland to forest area along river valley. From 2005 to 2010, there was 4.8% total areas changed in ecosystem types, and changing area was scattered. Ecosystem service value increased significantly after ecological control of rocky desertification. From 2000 to 2010, ecosystem service value increased 9.61×10⁷ Yuan in total. The increment in the early (from 2000 to 2005) and later (from 2005 to 2010) periods accounted for 18.2% and 81.8% of the total, respectively. The increase in the later period was more obvious than that in the early period. The increase rates for the two periods were respectively 3.49×10⁶ Yuan per year and 1.57×10⁷ Yuan per year. The results also showed carbon fixation and oxygen release, product supply and soil fertility were the main ecosystem services in the study area. Ecosystem service value increase resulted from ecosystem conversions from low service value types to high service value types. For example, from 2000 to 2010 868.60 hm² cultivated land, bare rock and waste slope transferred into economic ecosystem. On the other hand, it resulted from increase of internal ecosystem service value which was the dominant element of ecosystem service value with more than 80% contribution rate after ecological control. The spatial conversion among ecosystem types in the study area after ecological control was obvious. The converting proportion, place were closely correlated with quantity of ecological projects and implementation areas. Conversion of ecosystem types responded quickly to the ecological projects (early conversion area of ecosystem types accounted for 83.0% of the total conversion area), while service values substantially increased at the later period (when increased service values accounted for 81.8% of total increased values), indicating certain hysteresis of ecosystem service value response to the ecological management practice.