National parks are designed, in part, to preserve the unique natural resources within their boundaries for the enjoyment of future generations. Climate change presents special management problems to the National Park Service for several reasons. Park boundaries cannot realistically be altered to accommodate species range shifts that are a response to changing climatic conditions. Surrounding regional landscapes generally have been altered in ways that limit connectivity between protected areas. Ecological responses to climate change often cascade through ecosystems in ways that are not immediately obvious. Finally, thresholds in ecosystem change present unwelcomed surprises to park managers. As a result, management goals and policies are undergoing review to meet the new reality of climate change and ecological research is playing an increasingly important role. The Climate Change in Mountain Ecosystems project started at Glacier National Park in 1991 to provide policy-relevant information to park managers that helps them anticipate mountain ecosystem responses to climate change. Several examples help illustrate research that is influencing changes in policy.
Results/Conclusions
The well-documented recession of glaciers in Glacier National Park is not only strikingly visible evidence of climate change, it also has specific ecological consequences for aquatic biota. Melting ice in late summer regulates stream temperature for coldwater-adapted species such as bull trout and westslope cutthroat trout. Warming water temperatures have contributed to isolation of genetically pure trout populations in upper reaches of watersheds and allowed hybridizing introduced fish species to compromise the genetic integrity of valley bottom trout populations. Policy shifts to allow more aggressive taking of introduced species, constructing of barriers to protect genetically pure populations, and attempts to reduce other stresses to bull trout and westslope cutthroat trout have resulted. In another example, seasonal snowpack is melting as much as a month earlier and average elevation of the snowline is rising due to climate change. This is expected to continue and reduce the frequency and magnitude of snow avalanches that maintain open paths or swaths through mid-elevation forests. Because these avalanche paths are critical habitat for a host of species, including the grizzly bear, the infilling by trees in the absence of regular snow avalanche disturbance is a cause for concern. The policy implications of these and other ecosystem responses to climate change are part of ongoing dialogue between ecologists and managers.
