Geography Reference
In-Depth Information
Figure 20.1
Latitudinal
distribution of natural
freshwater wetlands.
Source:
Groombridge1992.
they also meet those for both forest and coastal
systems (Groombridge 1992), indicating the
integral role that wetlands play in the broader
ecology of countries and regions. Another
problem encountered in assessing wetlands is
delineation of their boundaries, typically an
ecotone between the wetland and either aquatic
or terrestrial habitats (Committee on
Characterisation of Wetlands 1995).
The human perception of wetlands has always
been ambivalent. Misunderstandings over their
ecology and functioning lead to their perception
as a hazardous wasteland, or an area to be drained
for agriculture and other arguably more
productive land uses (Box 20.2). Historically,
wetlands were considered hazardous, marginal
waterlogged lands, harbouring disease. Malaria,
dengue fever, filiariasis and yellow fever are all
tropical diseases associated with wetlands (Dugan
1993). However, local people often respect and
understand wetlands as a resource and are
dependent on them (Box 20.2), while more
recently, others are happy to enjoy them as tourists
or in the comfort of their own home via the
medium of television. This ambivalence has
resulted in conflict and a substantial loss of
wetlands due to, e.g. drainage, and degradation of
many of the remaining wetlands due to, e.g.
pollution or over-abstraction. More recently,
research has begun to show the fundamental role
that wetlands play locally, regionally and globally,
highlighting the need for geographers to apply
knowledge and skills in order to resolve not only
environmental problems but also social and
economic issues. This requires inputs from
historical, physical, environmental and human
geographers on an interdisciplinary basis.
WHY ARE WETLANDS IMPORTANT?
Wetlands are one of the most productive ecosystems
in the world. Recently, more emphasis has been
placed on understanding and valuing wetlands and
their functions, and on the need to achieve
sustainable management. The conflict over wetlands
is in large measure a failing of the current socio-
economic systems to recognise their value. Different
ways of categorising wetland functions and values
have been put forward (Williams 1990). As a system,
the total economic value (TEV) of wetlands has
often been underestimated. This TEV includes
direct
use values
of products such as fish and fuelwood and
services, such as recreation and transport;
indirect use
values
(or functional values) such as flood control
and storm protection provided by e.g. mangroves;
option values,
which could be discovered in the
future; and
intrinsic values,
the value of the wetland
