188.8.131.52. Impacts of Land-Use Change
Extraction of oil and mineral resources is likely to be the greatest direct
human disturbance in the arctic. Although the spatial extent of these disturbances
is small, their impacts can be far-reaching because of road and pipeline systems
associated with them (Walker et al., 1987). Roads in particular open previously
inaccessible areas to new development, either directly related to tourism and
hunting or to support facilities for resource extraction.
Changes in goods and services in alpine ecosystems are likely to be dominated
by changes in land use associated with grazing, recreation, and other direct
impacts, as a result of their proximity to population centers (Körner,
1999; Walker et al., 2001). Many of the alpine zones with greatest biodiversity,
such as the Caucasus and Himalayas, are areas where human population pressures
may lead to most pronounced land-use change in alpine zones (Akakhanjanz and
Breckle, 1995). Direct impacts from human activities are likely to be most pronounced
in lower elevational zones that are most accessible to people (Körner,
1999). Improved road access to alpine areas often increases human use for recreation,
mining, and grazing and increased forestry pressure at lower elevations (Miller
et al., 1996). Overgrazing and trampling by people and animals may tend to destabilize
vegetation, leading to erosion and loss of soils that are the long-term basis
of the productive capacity of alpine ecosystems.
Alpine areas that are downwind of human population or industrial centers experience
substantial rates of nitrogen deposition and acid rain (Körner, 1999).
Continued nitrogen deposition at high altitudes, along with changes in land
use that lead to soil erosion, can threaten provision of clean water to surrounding
regions. Nitrogen deposition occurs primarily during the winter and is transmitted
directly to streams during snowmelt, so it readily enters water supplies (Körner,
1999). Many places that use water from alpine areas depend on slow release of
the water by melting of snowfields in spring and summer. Warming is likely to
create a shortened snowmelt season, with rapid water release creating floods
and, later, growing-season droughts. These changes in seasonality, combined
with increased harvest in montane forests, would amplify floods.