DFID in its conceptual frameworks of Sustainable Livelihoods Approaches (SLAs) defines five types of asset: human capital, social capital (the ability to draw on support through membership of social groups), natural capital, physical capital, and financial capital for achieving poverty elimination. But most services provided by the natural environment (natural capital) to human society are not captured by GDP or other conventional macro-economic indicators, because, they are not directly traded in markets. Provisioning services (food, fibre and water) and a few cultural services (such as recreation and tourism) are somehow calculated but value of regulating services (water and climate regulation) is not calculated yet, although research on regulating services is developing rapidly.
