(NWF) List the 4 major categories of
ecosystem services:

Explanation:

Ecosystem services, outputs, conditions, are processes of natural systems that directly or indirectly benefit humans or enhance social welfare. Ecosystem services can benefit people in many ways, either directly or as inputs into the production of other goods and services. For example, the pollination of crops provided by bees and other organisms contributes to food production and is thus considered an ecosystem service. Another example is the attenuation of flooding in residential areas provided by riparian buffers and wetlands.

Two criteria distinguish ecosystem services from other ecosystem conditions or processes. First, an ecosystem service must be linked to an identifiable set of human beneficiaries. The service can be an aspect or consequence of an ecological condition and can directly or indirectly benefit or profit the beneficiaries. Second, physical and institutional access constraints must not prevent people from realizing those benefits. For example, increases in fish abundance can enhance the welfare of those engaged in commercial or recreational fishing, but only if those increases occur in areas where fishing occurs. Conditions or processes of ecosystems that cannot be linked to the welfare of identifiable beneficiary groups are not ecosystem services. For example, changes in fish abundance in areas not used by humans and that have no direct or indirect effect on human benefits are not ecosystem services.