Farmland ecosystem function service values in Zhangjiajie City

As the main location of National Wuling Mountain Ecological Function Zone for Biodiversity and Conservation of Water and Soil, farmland ecosystem should have multiple service functions in Zhangjiajie City. Profit and loss values of farmland ecosystem function service in Zhangjiajie City were estimated from three aspects; service function benefit, governance cost of damaged environment and net benefit of function service. Please provide more information of the evaluation method. The results indicate that from 2006 to 2012, the annual average of service function benefits, the annual average of governance cost for damaged environment and the annual average of net benefit from service function was 28.40, 0.59 and 27.81 billion Yuan respectively. Among them, 95.67% of the service function benefits were contributed by planting production, photosynthetic oxygen release, nutrient cycling and integrated fixed CO₂. 91.52% of governance costs for damaged environment were caused by greenhouse gas emissions, chemical fertilizer pollution and pesticide pollution. Temporal and spatial variations of the profit and loss values of farmland ecosystem function service showed that the annual averages of service function benefits and governance cost for damaged environment were significantly different among all the counties and districts of Zhangjiajie City. There were significant negative correlations between annual average of service function benefits and time however the negative correlation between governance cost for damaged environment and time was not significant from2006 to 2012.