Mountain ecosystems consist of alpine zones characterized by rugged, partially
vegetated open terrain with snowfields and rocky ridges above montane forests. These
alpine grasslands and shrublands, sub-alpine parkland and montane forest habitats are high
energy environments characterized by prolonged snow cover, steep terrain, extremes of
heat and cold, and intense ultraviolet radiation. With increasing elevation, time for growth
and reproduction decreases, environmental conditions become harsher with increasing
stochasticity; at the highest elevations, hypoxic conditions add additional energetic living
costs. For plants, dispersal of pollen, seeds or ramets may be limited by topography,
weather conditions and patchy habitats where access to nutrients may be limited. These
factors result in short, intense growing and breeding seasons.
Only a few plants and animals live exclusively in the alpine, while many mountain
species breed in both alpine and lower elevation habitats. To cope with their difficult
environmental conditions, plants and wildlife living in mountain habitats have adopted a
slower lifestyle where they may produce fewer offspring each year compared to
populations at low elevations, but many live longer and thus have more years to breed
and replace themselves. The compression of several habitat types and variable
environmental conditions within small spatial areas often results in high species
endemism and biodiversity in mountain areas. High elevation ecosystems are used by
migrating wildlife after breeding, a time when mountain habitats offer rich food
resources and when productivity in many low elevation habitats has declined. Thus, we
need to include life history periods outside the breeding season to accurately evaluate
the biodiversity of mountain habitats. Connectivity is a key ecological process for high
elevation wildlife populations. Connectivity needs to be maintained (1) among patchy
habitat islands for breeding populations, (2) along mountain corridors for north-south
migrants, and also (3) between alpine and adjacent lower elevation habitats and valley
bottoms for both breeding populations and migrants.
Many European and Asian mountain ecosystems are heavily altered by agriculture,
forestry and intense recreational activities such as skiing developments. Although most
alpine habitats in North America appear relatively intact, ecological change is also
taking place over extensive areas, with some areas showing deterioration due to
recreational activities, livestock grazing, mining, and airborne contaminants. Ski area
development has dramatically increased in America and Europe. In addition to habitat loss
from resort areas and ski pistes, high elevation habitats impacted by ski developments are
vulnerable to erosion, with slow recovery of vegetation after such disturbances. On a
landscape scale, developed valley bottoms constitute dispersal barriers for wildlife species
with seasonal vertical movements. The cumulative impacts of ski developments and
climate change increase the challenge of maintaining the key ecological processes for the
persistence of flora and fauna in sensitive mountain ecosystems.
Keywords: Mountain environments, ecological processes, connectivity, endemism,
human alterations, life history traits, wildlife adaptations, alpine ecology, elevational
gradients and biodiversity, life history variation, alpine plants, mountain breeding
vertebrates, impacts of skiing on vertebrate ecology.
