Geoscience Reference
In-Depth Information
Figure 18-4.
During the Little Ice Age in Norway, Jostedalsbreen (ice cap on far horizon) expanded and outlet
glaciers descended into its surrounding valleys. Many farms, such as the one to the right, had to be abandoned
because the climate turned so cold, and the local population suffered great poverty (Grove 1988). Glacier advances
reached a maximum
c
. AD 1750; rapid glacier retreat took place after about 1850 (Aarseth et al. 1980).
Vanndalstølen in foreground; Jostedal (valley) in middle distance. Photo by J.S. Aber.
and enforceable property and tenure rights,
whether based on private, state or common
property systems, have demonstrated their
ability to balance ecosystem and human uses
and remain viable systems. Integrating
principles of sustainability into resource
management practices could prove effective
in supporting the long-term health of an
ecosystem.
In the face of extreme pressures and com-
peting demands for a wetland site, the lack
of clearly dei ned institutional rules of
resource use, access, and extraction, as seen
in open-access systems, may result in overuse
and degradation. Likewise, the lack of ade-
quate environmental governance at the local,
state or federal levels may also lead to “wild
west” exploitation and resource degradation.
Corrupt governance systems lacking transpar-
ency and accountability provide few incen-
tives for sustainable resource management.
Shared wetland challenges - Many of the
world's great wetlands, including the Pan-
tanal, Okavango, Sundarban and prairie
pothole region straddle country borders (see
chapters 14 and 15). In addition, upstream
uses of a river and water diversions within
one country can inl uence the health of
downstream l oodplain and deltaic habitats
in another. Such instances of shared wetlands
are numerous around the globe. As the
demand for fresh water becomes more acute,
conl icts over access and use are likely to
become more common. Conservation and
management in such instances is confounded
by regional politics. Equitably formulated
joint agreements may help in the shared gov-
ernance of such resources. In other cases, the
involvement of international or non-
governmental organizations might become
necessary to ensure equity of access and use.
Wetland degradation - Pollution and habitat
fragmentation heighten the vulnerability of
wetlands to further degradation (see also
chapter 10). Such stressors reduce the adap-
tive capacity of ecosystems and make them
particularly susceptible to even small threats.
Stricter pollution control mechanisms could
