Ecosystems as Natural Assets

It is now standard in economics to model natural resources as a special form of capital that can be depleted or accumulated. The following review shows how such an approach can be extended to ecosystems, implying that they are a form of natural asset that produces a flow of beneficial goods and services over time. The review includes a discussion of valuing ecosystem services, focusing on the problem of benefits that vary spatially across landscapes and illustrated with the example of coastal ecosystems. The starting point of the basic natural asset model is the assumption that the amount of an ecological landscape that is allowed to remain intact must compete with other assets in the portfolio of wealth owners in the economy. The model shows the importance of valuing ecosystem services to the optimal allocation of landscape among competing uses. It includes the possibility of an ecological transition, when it becomes technologically feasible to restore developed land as ecological landscape. The basic model is then extended to allow for the value of an ecosystem service and the costs of maintaining this service to vary with the spatial distance across the natural landscape; for the implications when the economy is opened to trade; and finally, for examining the effects of the risk of ecological collapse.