Skip to main content
U.S. flag

An official website of the United States government

Widespread increase of tree mortality rates in the western United States

Author(s):

Phillip J. van Mantgem
Nathan L. Stephenson
Lori D. Daniels
Jerry F. Franklin
Peter Z. Fule
Mark E. Harmon
Andrew J. Larson
Jeremy M. Smith
Alan H. Taylor
Thomas T. Veblen

Year:

2009

Publication type:

Newspaper Article

Primary Station(s):

Rocky Mountain Research Station

Source:

Science. 323(23): 521-524.

Description

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.

Citation

van Mantgem, Phillip J.; Stephenson, Nathan L.; Byrne, John C.; Daniels, Lori D.; Franklin, Jerry F.; Fule, 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(23): 521-524.

Publication Notes

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
https://www.fs.usda.gov/treesearch/pubs/34002