关键词: 生态学, 气体调节功能, 价值评价, 稻田生态系统

Abstract: The welfare served by croplands has been underestimated.Besides supplying food and providing straw,croplands support many other functions and services such as nutrients transforming,pollination,biological control,supplying beautiful scenery,recreation,and so on.In this study,we examined the gas regulation services supported by rice paddy ecosystems,based on the results of field experiments in Wusi Farm of Shanghai in 2002.And the values of gas regulation by paddy rice ecosystems with different N-fertilization treatments were also estimated with ecological economics methods.The results indicated that two kinds of gas regulation were provided by paddy fields:one was O2 emission,and the other was Greenhouse Gases(GHGs) regulation(including CO2 uptake,CH4 and N2O emission).First,in the cultivation period,O2 emission of rice paddy ecosystems ranged from 1.65×104kg·hm-2 to 3.85×104kg·hm-2 along with increment of N fertilizer application,and the values ranged from 6.22×103yuan·hm-2 to 11.87×103yuan·hm-2 in the same trend.Second,rice paddy ecosystems emitted GHGs,but also fixed CO2 from atmosphere.In CO2 equivalent,the quantities of GHGs regulation ranged from -997kgCO2-C·hm-2 to 2 787kgCO2-C·hm-2,and the values ranged from -751yuan·hm-2 to 2 098yuan·hm-2.Third,the integrated values of gas regulation by rice paddy ecosystems ranged from 5 467yuan·hm-2 to 1.28×104yuan·hm-2.In this study,we are trying to provide a fair method to evaluate the values of croplands,to support an effective way to recognize the welfare served by croplands,especially by paddy fields and to promote the sustainability of cropland ecosystems and yet the sustainability of human kinds.

Key words: ecology, gas regulation services, economic value assessment, rice paddy ecosystems