Environmental Engineering Reference
In-Depth Information
by individuals or groups of individuals, who are interested in maximiz-
ing their private benei ts through the production of particular products
that have a specii c market value to them (for example, Kirby, 2000).
However, creating a commercially increased output through a change in
land-use may not in reality result in the most productive ecosystem if as
a consequence the non-marketed values of the ecosystem are reduced or
eliminated. Policy-makers and governments have frequently overlooked
the non-market values of ecosystems with the consequence that a change
in land-use has occurred in favour of the commercial system of produc-
tion, thus leading to an overall reduction in the net benei ts produced by
the ecosystem (Godoy, 1992). This has resulted in policies that have mis-
directed resource use away from the most economically valuable form of
production and towards maximizing i nancial outputs.
In order to make rational decisions on issues of natural resource man-
agement it is therefore important that consideration is given by policy
analysts to all aspects of an ecosystem's value. Only if this is undertaken
can the total economic worth of the ecosystem be estimated and an ef ec-
tive comparison of its value under dif erent uses made. Valuation of
ecosystem productivity can be undertaken by numerous methodologies
(see, for example, Dixon and Sherman, 1990; Heywood, 1995). However,
this chapter concentrates on one type of methodology that is particularly
useful for the valuation of non-marketed and marketed values associated
with biological resources that support economic activity. This is the pro-
duction function approach.
Tanzanian land-use issues
As more detailed descriptions of the land-use problems of Tanzania are
given elsewhere (Quinn and Ockwell, Chapter 9, this volume), this chapter
gives only a brief overview of the relevant issues. The Tanzanian semi-arid
to arid climate has a rainfall ranging from 400 to 1200 mm. The result-
ing vegetation varies from grasslands to savanna thornbush and wooded
savanna in higher rainfall areas. The population density is relatively low
and at least 11 per cent of the population are below the poverty line. Much
of the land area is still under open access or some form of common prop-
erty tenure.
The traditional form of land-use in semi-arid Tanzania has been pas-
toralism, dei ned as a production system where at least 50 per cent of
production (subsistence and marketed) comes from livestock or livestock-
related activities. This is predominantly an extensive production system,
ranging from nomadism, where no form of cultivation takes place, to
semi-transhumance, where part of the family is sedentary and practises
cultivation (Niamir-Fuller, 1998).
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