Environmental Engineering Reference
In-Depth Information
Commercial values
Extraction of timber or production of livestock from an ecosystem will
directly produce revenue for the land-users. If they are marketed, their value
will be equal to the revenue from selling the timber or livestock minus the
costs of production and transport to market (Godoy, 1992). If they are not
marketed but kept for home consumption they will also have a value although
this will be considerably harder to impute, and may not be equal to the value
that they would realize if they were sold on the open market (Godoy, 1992).
Non-timber and non-meat values
A savanna or forest ecosystem can potentially provide a great number of
non-timber or non-meat goods and services. Studies have shown that in
the case of a forest ecosystem, local people living in and around it regularly
use a large number of forest products. Many of these products may be
marketed and thus have market values, for example, wild fruit and insects,
wood for construction purposes, herbs and medicinal plants (Fuentes,
1980; Oommachan and Masih, 1988). However, many goods and services
may be extracted and only used for home consumption, in which case they
will not have an immediately identii able market value (Peters et al., 1989).
In the case of savanna ecosystems, a large number of products including
palms, grasses, reeds, fruits and wild mushrooms have all been shown to be
used by the local inhabitants (Campbell et al., 2000a; IIED and HNWCP,
1997). In addition, livestock production may produce a number of benei ts
besides those of meat, for example, transport, which must be included in
an evaluation of the productivity of the system. As with forest products,
these products may or may not have a direct market value, depending on
the use to which they are put.
Regardless of whether either of these products are marketed or non-
marketed, they can be described as direct-use goods. As this name implies,
these are goods that are supplied directly from the ecosystem and that
may be either domesticated or wild. In this sense, forestry and livestock
production as well as products derived from i shing and hunting are
included.
External benei ts
The third category of goods and services that can be derived from ecosys-
tems are described as indirect-use resources. Many ecosystems will provide
invisible benei ts to other ecosystems or people, both within the geographi-
cal area of the ecosystem, as well as outside it. In the case of both forest and
savanna ecosystems, these external benei ts can be considered to exist at two
separate levels. A number of empirical studies have shown that forest ecosys-
tems provide protection for other ecosystems located downstream from the
