Review of agro-ecosystem services and their values

Agro-ecosystem has become an integrated crop production system with significant human disturbances.Compared with natural ecosystems,the crop production function of agro-ecosystem has intensified while impairing other ecosystem services such as gas/water regulation,soil conservation and biodiversity maintenance.In recent years,agro-ecosystem services have become more and more scarce because of large demand by the rapid global development.This has resulted in an increasing concern about the values and services of agro-ecosystems across the globe.This study argued that biodiversity of agro-ecosystem was the physical basis for ecosystem services.The study reviewed classical studies on agro-ecosystem services,including production supply,carbon sequestration,soil conservation,nutrient cycle and water regulation,and on the comprehensive assessment of agro-ecosystem services.The study further discussed the passive effects(e.g.,non-point pollution,CH4/N2O emissions and heavy metal pollution) of agricultural production on human society and the environment.It was necessary that farmers and government organs realized the importance of the tradeoff between the advantages and disadvantages of agricultural production.The various effects of agricultural production systems(e.g.,integrated,conventional and organic agro-ecosystems,and combined food/forest systems) on the services of different agro-ecosystems were further compared.It was noted that only multi-functional agricultural production systems maximized welfare supported by agro-ecosystem services.Four key measures for developing multi-functional agro-ecosystems in China were eventually listed.The measures included:(1) ensuring the existence of farmlands of 120 million hm2;(2) reasonable arrangements of the distribution of forests,grasslands,wetlands and water resources;(3) encouraging tourism in farming regions in order to strengthen the cultural functions of agro-ecosystems;and(4) stepwise implementation of ecological compensation strategies for adoption of agro-ecosystems.