Agriculture, water, and ecosystems: avoiding the costs of going too far
Types of ecosystem services
Goods produced or provided by ecosystems
Benefits from regulation of ecosystem processes
Factors necessary for producing ecosystem services
Nonmaterial benefits from ecosystems
Source: Adapted from MEA 2003.
Whether an ecosystem is managed primarily for food production, water regulation, or for other services (figure 6.2), it is possible to secure these for the long term only if basic eco- system functioning is maintained. In many agroecosystems considerable effort goes into ensuring crop production, but often at the expense of other important services, such as fisheries (Kura and others 2004), freshwater supply (Vörösmarty, Lévêque, and Revenga 2005), and regulation of floods (Daily and others 1997; Bravo de Guenni 2005).
Biodiversity—variability and diversity within and among species, habitats, and eco- system services—is important for supporting ecosystem services and has value in its own right. Further, biodiversity can act as an insurance mechanism by increasing ecosystem resilience (box 6.3). Some species that do not seem to have an important role in ecosystems under stable conditions may be crucial in the recovery of an ecosystem after a disturbance. Similarly, if one species is lost, another with similar characteristics may be able to replace it. While the concept of biodiversity comprises ecosystems, species, and genetic components, most of the discussion in this chapter focuses on the functional role of ecosystems and spe- cies (or taxa) in terms of the ecosystem services that they provide.
ere is increasing evidence that ecosystems play an important role in poverty reduction
(Silvius, Onela, and Verhagen 2000; WRI and others 2005). Many rural poor people rely on a variety of sources of income and subsistence activities that are based on ecosystems and are thus most directly vulnerable to the loss of ecosystem services [established]. ese sources of
income, often generated by women and children, include small-scale farming and livestock rearing, fishing, hunting, and collecting firewood and other ecosystem products that may be sold for cash or used directly by households. Floodplain wetlands, for example, support many human activities, including fisheries, cropping, and gardening (photos 6.1–6.3).