Natural environment as a composition of ecosystems provides a variety of ecosystem services to human beings. however, Its capacity to accommodate human need is limited. When the pressure exceed the capacity, ecosystems may change irreversibly and enter to a unstable and unsustainable state. This sounds self-evident to every one but on paper only, no real experience. This course interpret high resolution images and calculate the land price, agricultural products, and CO2 absorptions through simple exercise. Through the processes we will learn the procedure of ecosystem assessment, the knowledge to understand the status and functions, and services of environment. By putting the results on the frame of stock and flow we will rethink the role of land capital, industrial capital and natural capital in modern society, and clarify the precondition of sustainability.