Evaluation of ecosystem service has been one of the hottest issues in the field of ecology and ecological economics since the publication of Costanza's famous article in Nature in 1997. Agricultural ecosystem (farmland and orchard) is a semi-natural and semi-manipulated ecosystem, which not only provides people with grains, vegetables, and fiber, but also plays an important role in ecological buffers, regulation for gas regulation, soil and water conservation, and environmental decontamination. However, agricultural ecosystem also has negative effects on our environment, such as excessive water resource consumption, greenhouse gas emission, and environmental pollution caused by fertilizer and pesticide application. Agricultural ecosystem service has profound effects on the sustainable development of human society, and its study is one of the research frontiers in ecology. However, there are only a few research reports on the agricultural ecosystem services in China, especially in the rapid urbanized areas.
This paper, based on the connotation of ecosystem service, developed an evaluation index system for assessing the agricultural ecosystem services value in Foshan City in Guangdong Province and quantified the positive benefits and negative benefits of agricultural ecosystem services in Foshan City during the period of 2000-2009, which locates in the Pearl River Delta (PRD), one of the most powerful economic areas in China and covers 5 districts with Chancheng, Nanhai, Shunde, Sanshui and Gaoming. The results showed that the total service value of agricultural ecosystem in Foshan increased from ￥5.88×10⁹ in 2000 to ￥7.31×10⁹ in 2009 and a net increase of ￥1.43×10⁹ was achieved during this decade. The products provision service, which was one of the most important services of agricultural ecosystem in Foshan, was significantly affected by technology and management and there is a potential for its further improvement in this region. The proportion of its products provision value to the positive benefits increased from 30.47% in 2000 to 61.15% in 2009 while its proporation to the total value increased from 36.86% in 2000 to 69.33% in 2009, indicating that the other services were being gradually weakened except for the products provision. For the period of study, the positive benefits of agricultural ecosystem were greater than the negative benefits while the gap between them was widening each year, and the ratio of positive benefits to negative benefits increased from 5.77∶1 in 2000 to 8.48∶1 in 2009. Water resource consumption and greenhouse gas emission were the most serious problems of agricultural ecosystem services in Foshan City and the combined proportion of these two components in the total environmental costs value was 82.79% in 2000 and 78.40% in 2009, indicating an urgency to take effective measures to decrease the irrigation water consumption and to change the farming system in the region in order to minimize those adverse impacts on the agricultural environment. The current study demonstrated that agricultural ecosystem services have both positive and negative benefits apart from providing agricultural products. To attain sustainable development of the nature, economy and society ecosystem in fast urbanized areas, evaluation of agricultural ecosystem service should be imperative.