Abstract Title: Fire and Ice: Understanding the Legacy of the Little Ice Age for Contemporary Landscape Patterns and Processes in Glacier National Park, Montana, USA
Author(s):
Gregory T. Pederson - Big Sky Institute - Montana State University
Daniel B. Fagre PhD - U.S. Geological Survey - Northern Rocky Mountain Science Center
Stephen T. Gray PhD - U.S. Geological Survey - Desert Laboratory
Lisa J. Graumlich PhD - Big Sky Institute - Montana State University
Abstract:
Over the past century landscapes throughout Glacier National Park (GNP), Montana, have undergone a series of dramatic changes. In terms of both cultural and ecological impact the most stunning of these changes has been the rapid retreat of glaciers and perennial snow/ice fields: ~73% reduction in area during the 20th century. Large fires in 2003 have similarly changed Park landscapes and renewed interest in the role of catastrophic disturbances. Here we explore the role of climate as a driver of landscape reorganization in GNP. To investigate the linkage between glacial dynamics and climate we compare recession chronologies of the Jackson, Agassiz, and Sperry Glaciers with tree-ring based reconstructions of climatic indices related to summer ablation and winter accumulation extending back to A.D. 1700. Using a summer drought reconstruction and spatially extensive fire histories developed from tree-ring dated stand ages, we also investigate the role of climate in controlling regional disturbances for the period A.D. 1540-2003. Results indicate that decadal to multidecadal persistentence in summer moisture regimes and winter snowpack anomalies have played a major role in driving regional patterns of glacial dynamics. For example, the largest glacial advance (late-18th - mid-19th centuries) of the Little Ice Age, coincided with a > 50 yr period of cool/wet summer conditions, and deep winter snowpack. Similarly, decadal-scale moisture regimes are linked to fire frequency and area burned. These findings from GNP suggest the importance of decadal and longer-scale climate variability in shaping the structure and function of ecosystems throughout the Rocky Mountain Region.
