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�����B��ؚ�����о�(Ӣ��)�����ݺ��飺Ecosystems provide a huge variety of goods and services that are important to us all,but 60% of the world's ecosystem services are being degraded or used unsustainably��Millennium Ecosystem Assessment, 2005 ��. This deterioration is affecting growthand development and will continue to do so into the future.Some of the poorest and most vulnerable groups in society, especially those living inrural areas, are the most directly dependent on ecosystem services and therefore arethe most vulnerable to sudden changes in ecosystem service provision and to poorecosystem management. This dependence is particularly exposed when there arenatural and human disasters such as drought, famine and floods. Poor people are alsoless able to access or purchase substitutes to ecosystem services that they directly relyon.