Natural capital is the world's stock of natural resources, which includes geology, soils, air, water and all living organisms. Some natural capital assets provide people with free goods and services, often called ecosystem services. All of these underpin our economy and society, and thus make human life possible. It is an extension of the economic notion of capital (resources which enable the production of more resources) to goods and services provided by the natural environment. For example, a well-maintained forest or river may provide an indefinitely sustainable flow of new trees or fish, whereas over-use of those resources may lead to a permanent decline in timber availability or fish stocks. Natural capital also provides people with essential services, like water catchment, erosion control and crop pollination by insects, which in turn ensure the long-term viability of other natural resources. Since the continuous supply of services from the available natural capital assets is dependent upon a healthy, functioning environment, the structure and diversity of habitats and ecosystems are important components of natural capital. Methods, called 'natural capital asset checks', help decision-makers understand how changes in the current and future performance of natural capital assets will impact human well-being and the economy. History of the concept The term 'natural capital' was first used in 1973 by E.F. Schumacher in his book Small Is Beautiful and was developed further by Herman Daly, Robert Costanza, and other founders of the science of Ecological Economics, as part of a comprehensive critique of the shortcomings of conventional economics. Natural capital is a concept central to economic assessment ecosystem services valuation which revolves around the idea, that non-human life produces goods and services that are essential to life. Thus, natural capital is essential to the sustainability of the economy. In a traditional economic analysis of the factors of production, natural capital would usually be classified as "land" distinct from traditional "capital." The historical distinction between "land" and "capital" defined “land” as naturally occurring with a fixed supply, whereas “capital,” as originally defined referred only to man-made goods. (e.g., Georgism) It is, however, misleading to view "land" as if its productive capacity is fixed, because natural capital can be improved or degraded by the actions of man over time (see Environmental degradation). Moreover, natural capital yields benefits and goods, such as timber or food, which can be harvested by humans. These benefits are similar to those realized by