北京郊区农田生态系统服务功能价值的评估研究

由于耕地面积显著减少,京郊农田生态系统总服务价值由1996年的4513384.07×10⁴元下降到2002年的3426990.22×10⁴元,减少10⁸6393.85×10⁴元。其中粮食作物的各项服务功能价值在逐年降低,其它作物有不同程度的提高。6年间农业总服务价值平均值大约是其农业增加值的8倍,相当于8元服务价值产出1元经济生产力。6年间接价值平均为3461605.08×10⁴元,大约为直接价值的6倍。农民承担了保护耕地资源的责任,却没有获得相应收益。从构成来看,在京郊现有耕作制度下,提供农产品份额为12.41%;调节大气成分和净化环境价值占据绝对主体,两者之和占农田生态系统总服务价值的77%(净化环境占37.51%,调节大气成分占39.48%);土壤积累有机质价值为4.4%;农业观光游憩价值为3.8%;维持养分循环为1.27%;蓄水功能为2.21%;而保持土壤服务功能最低,仅占0.01%。

Studies on Service Value Evaluation of Agricultural Ecosystem in Beijing Region

The agricultural ecosystem in Beijing rural areas plays a special role in maintaining the environmental function of the city.At present,because area of farmland in the area is decrea-sing,a series of ecological problems are becoming more and more serious.The accurate valuation of farmland ecosystem services is very important to reserve rational development of agricultural resources.In this paper,the agricultural ecosystem (farmland and orchard) service values are evaluated by various methods such as market value,substitution engineering,shadow price,pportunity cost for various crop types.Some index systems are selected for assessment of agricultural ecosystem services,which consist of 11 service indexes such as agricultural products,CO2 fixation and O2 release,environment purifying such as air quality purifying,sewage treatment,dung decomposition,OM accumulation in soil,nutrients cycle,soil conservation,water storage,and agriculture tourism.The results showed that the total service value of agricultural ecosystem decreased from 45133.84 million yuan in 1996 to 34 269.90 million yuan in 2002 a decrease of 10 863.93 million yuan,of which various values of food crops decreased and others increased to some extent.The total average value of agriculture services during six years was eight times of the production value.The total average value of agricultural ecosystem services during this period of time added up to 91 567.61 million yuan with indirect values being 34 616.05 million yuan,i.e.,six times of the direct values.In terms of composition,under present cultivation system,the value of farm products is 12.41%;the total value,including carbon fixation,oxygen production and environment purification,are very great,making up 77%(carbon fixation and oxygen production 39.48% and environment purification 37.51%);the value of soil OM accumulation 4.4%;nutrients cycle maintenance 1.27%;water-holding and agricultural tourism 2.21% and 3.8% respectively; and soil conservation 0.01%.Therefore,agricultural ecosystem has provided huge indirect values to human beings besides direct values.