Geoscience Reference
In-Depth Information
necessitate local ecosystem adaptations and
they would also pose serious implications for
the regional and global climate system.
The Rocky Mountain region in southern
Colorado includes several distinct mountain
ranges and intervening valleys, in which eleva-
tions range from around 2300 m to over 4000 m.
Climatic conditions and vegetation cover vary
greatly over short distances. Mires and fens
are found in moraine potholes of glaciated
valleys above 3000 m in the Culebra Range.
These montane wetlands display diverse his-
tories depending on when peat began to accu-
mulate, drought episodes, and beaver activity.
The San Luis Valley is a desert environment
that surprisingly enjoys considerable surface
and ground water derived from surrounding
mountain ranges. Many wetland habitats are
protected in a national park, three national wild-
life refuges, and several state wildlife areas. The
modern abundance and diversity of waterfowl
and shorebirds in the San Luis Valley are similar
to pre-European accounts.
The impacts of climate change may have far-
reaching consequences for the polar regions of
the world. Wetlands and dependent populations
in these fragile high-latitude environments face
unique challenges. Ice and permafrost play sig-
nii cant roles in molding these landscapes, while
short summer months allow for surface melting
and support a tremendous diversity and density
of species. The Arctic Coastal Plain, the Yukon
Delta in Alaska and the Lena Delta in Russia
have landscapes with thousands of lakes, water-
i lled troughs and shallow depressions, which
host migratory nesting birds by the millions
during the summer. Large mammals like the
caribou and important i sh species, such as the
salmon, play vital roles in the cultural traditions
and economic livelihoods of resident native
communities. Changing climate patterns and
warming trends may inl uence ecosystem shifts
across the Arctic. As in the past, the adaptive
capacities of resident communities will be tested
in the decades to come.
17.5 Summary
High latitudes and altitudes include regions
with mild to severe climates characterized by
cold temperatures. Glaciers, permafrost and
periglacial phenomena are common features
in these realms. Included in these zones are
vast expanses of boreal forests across northern
Eurasia and North America as well as tundra
regions still farther north. At lower latitudes,
similar conditions may exist on high moun-
tain peaks and plateaus. Mountains display
distinct climatic differences from surround-
ing terrain, which include colder temperature,
enhanced cloud cover, and more precipitation.
High-altitude and -latitude environments have
received relatively less scientii c study than have
more hospitable regions of the Earth's surface.
Nonetheless, high-altitude and -latitude wet-
lands play important environmental roles for
habitats and global biogeochemical cycles.
The páramo habitat consists of alpine shrub
and grassland situated in the interval between
the upper forest limit and perennial snow cover
in Colombia, Ecuador and Venezuela. This zone
is almost constantly in clouds; rain falls most
days during the summer, and snow falls during
the winter. Wetland conditions are widespread in
formerly glaciated valleys and mesas including
mires and wet meadows with histosols. The most
characteristic plants are Espeletiinae, commonly
known as frailejóns, which are endemic to this
environment and include nearly 140 named
species. Pleistocene and Holocene climatic l uc-
tuations resulted in substantial vertical shifts of
vegetation zones. Much of the modern páramo is
heavily inl uenced by human activity.
