Widespread increase of tree mortality rates in the western United States
Document Type: Journal Article
Author(s): Phillip J. van Mantgem; Nathan L. Stephenson; John C. Byrne; Lori D. Daniels; Jerry F. Franklin; Peter Z. Fulé; Mark E. Harmon; Andrew J. Larson; Jeremy M. Smith; Alan H. Taylor; Thomas T. Veblen
Publication Year: 2009

Cataloging Information

  • climate warming
  • mortality rates
  • tree mortality
  • western United States
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Record Last Modified: February 29, 2020
FRAMES Record Number: 12235

Annotated Bibliography

This document is part of the Southwest FireCLIME Annotated Bibliography, which includes published research related to the interactions between climate change, wildfire, and subsequent ecosystem effects in the southwestern U.S. The publications contained in the Bibliography have each been summarized to distill the outcomes as they pertain to fire and climate. Go to this document's record in the Southwest FireCLIME Annotated Bibliography.


Persistent changes in tree mortality rates can alter forest structure, composition, and ecosystem services such as carbon sequestration. Our analyses of longitudinal data from unmanaged old forests in the western United States showed that background (noncatastrophic) mortality rates have increased rapidly in recent decades, with doubling periods ranging from 17 to 29 years among regions. Increases were also pervasive across elevations, tree sizes, dominant genera, and past fire histories. Forest density and basal area declined slightly, which suggests that increasing mortality was not caused by endogenous increases in competition. Because mortality increased in small trees, the overall increase in mortality rates cannot be attributed solely to aging of large trees. Regional warming and consequent increases in water deficits are likely contributors to the increases in tree mortality rates.

Online Link(s):
van Mantgem, Phillip J.; Stephenson, Nathan L.; Byrne, John C.; Daniels, Lori D.; Franklin, Jerry F.; Fulé, Peter Z.; Harmon, Mark E.; Larson, Andrew J.; Smith, Jeremy M.; Taylor, Alan H.; Veblen, Thomas T. 2009. Widespread increase of tree mortality rates in the western United States. Science 323(5913):521-524.