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Widespread increase of tree mortality rates in the Western United States

Science

By:
, , , , , , , , , , and
DOI: 10.1126/science.1165000

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Abstract

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.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Widespread increase of tree mortality rates in the Western United States
Series title:
Science
DOI:
10.1126/science.1165000
Volume
323
Issue:
5913
Year Published:
2009
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Science
First page:
521
Last page:
524
Number of Pages:
4