Preface for Integrated Ecosystem Assessment of Western China
为《中国西部生态系统综合评估》一书所作的序言

Human well-being is dependent on ecosystems. Earth's mosaic of ecosystems - forests, grasslands, wetlands, streams, estuaries, and oceans - when functioning naturally, provide materials, conditions, and processes that sustain all life on this planet, including human life. The benefits that all living things obtain from ecosystems are called "ecosystem services." Some are very familiar to us, such as materials like food and timber that are essential for our lives and important parts of the global economy. What are equally important, but certainly less well recognized, are the array of services delivered by ecosystems that do not have easily assigned monetary values, but that make our lives possible. These include the purification of air and water, the decomposition of wastes, the recycling of nutrients on land and in the oceans, the pollination of crops, and the regulation of climate.