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Subalpine fir mortality and drought

Date: July 28, 2021

Mortality of subalpine fir is governed by different processes at various spatial scales.


A subalpine fir tree.
A subalpine fir tree.
Subalpine fir decline is a poorly understood phenomenon that has killed trees across millions of hectares in western North America with unknown consequences for future forest resilience. Causes of the tree mortality are poorly understood but include the western balsam bark beetle.

We used broad-scale geospatial data analysis combined with small scale forest stand and individual tree data to examine the relative importance of factors driving subalpine fir decline.

At the sub-continental scale, the extent of subalpine fir mortality was associated with prior drought. Moist topographic conditions were drivers at regional scales. At smaller stand and tree scale, the probability of mortality was influenced by tree diameter and proximity to previously dead trees.

Key Findings

  • Subalpine fir mortality is driven by different factors at different geographical scales.
  • Local biotic processes may play an important role in mediating drought-driven forest decline.
  • This work highlights the importance of examining factors driving ecological disturbances across multiple scales.

Featured Publications

Harvey, Brian J. ; Andrus, Robert A. ; Battaglia, Mike A. ; Negron, Jose ; Orrego, Alexandra ; Veblen, Thomas T. , 2021


Principal Investigators: 
Principal Investigators - External: 
Brian J. Harvey - University of Washington
External Partners: 
Robert A. Andrus, University of Colorado
Alexandra Orrego, Georgia State University
Thomas T. Veblen, University of Colorado
Research Location: 
Southern Rocky Mountains, Colorado Front Range