Assessment of private economic benefits and positive environmental externalities of tea plantation in China

摘要

Tea plantations are rapidly expanding in China and other countries in the tropical and subtropical zones, driven by relatively high private economic benefit. However, the impact of tea plantations on the regional environment, including ecosystem services and disservices are unclear. In this study, we developed an assessment framework for determining the private economic benefits and environmental externalities (the algebraic sum of the regulating services and disservices) of tea plantations in China. Our results showed that tea plantations provided private economic benefits of 5,652 yuan ha~(-1) year~(-1) (7.6 yuan=1 USD in 2007) for tea farmers, plus positive environmental externalities of 6,054 yuan ha~(-1) year~(-1) for the society. The environmental externalities were calculated as the sum of the value of four regulating services, including carbon sequestration (392 yuan ha~(-1) year~(-1)); soil retention (72 yuan ha~(-1) year~(-1)); soil fertility protection (3,189 yuan ha~(-1) year~(-1)) and water conservation (2,685 yuan ha~(-1) year~(-1)), and three disservices, including CO_2 emission (-39 yuan ha~(-1) year~(-1)), N_2O emission (-137 yuan ha~(-1) year~(-1)) and nonpoint source pollution (-108 yuan ha~(-1) year~(-1)). Before the private optimal level, the positive environmental externalities can be maintained by private economic benefits; if a social optimal level is required, subsidies from government are necessary.