ASSESSING SIMULATED ECOSYSTEM PROCESSES FOR CLIMATE VARIABILITY RESEARCH AT GLACIER NATIONAL-PARK, USA

Glacier National Park served as a test site for ecosystem analyses tha t involved a suite of integrated models embedded within a geographic i nformation system. The goal of the exercise was to provide managers wi th maps that could illustrate probable shifts in vegetation, net prima ry production (NPP), and hydrologic responses associated with two sele cted climatic scenarios. The climatic scenarios were (a) a recent 12-y r record of weather data, and (b) a reconstituted set that sequentiall y introduced in repeated 3-yr intervals wetter-cooler, drier-warmer, a nd typical conditions. To extrapolate the implications of changes in e cosystem processes and resulting growth and distribution of vegetation and snowpack, the model incorporated geographic data. With underlying digital elevation maps, soil depth and texture, extrapolated climate, and current information on vegetation types and satellite-derived est imates of leaf area indices, simulations were extended to envision how the park might look after 120 yr. The predictions of change included underlying processes affecting the availability of water and nitrogen. Considerable field data were acquired to compare with model predictio ns under current climatic conditions. In general, the integrated lands cape models of ecosystem processes had good agreement with measured NP P, snowpack, and streamflow, but the exercise revealed the difficulty and necessity of averaging point measurements across landscapes to ach ieve comparable results with modeled values. Under the extremely varia ble climate scenario significant changes in vegetation composition and growth as well as hydrologic responses were predicted across the park . In particular, a general rise in both the upper and lower limits of treeline was predicted. These shifts would probably occur along with a variety of disturbances (fire, insect, and disease outbreaks) as pred ictions of physiological stress (water, nutrients, light) altered comp etitive relations and hydrologic responses. The use of integrated land scape models applied in this exercise should provide managers with ins ights into the underlying processes important in maintaining community structure, and at the same time, locate where changes on the landscap e are most likely to occur.