Document Type

Article

Publication Date

9-20-2005

Abstract

We analyzed trends in a time series of photosynthetic activity across boreal North America over 22 years (1981 through 2003). Nearly 15% of the region displayed significant trends, of which just over half involved temperature-related increases in growing season length and photosynthetic intensity, mostly in tundra. In contrast, forest areas unaffected by fire during the study period declined in photosynthetic activity and showed no systematic change in growing season length. Stochastic changes across the time series were predominantly associated with a frequent and increasing fire disturbance regime. These trends have implications for the direction of feedbacks to the climate system and emphasize the importance of longer term synoptic observations of arctic and boreal biomes.

Publication Title

Proceedings of the National Academy of Sciences

Volume

102

Issue

38

First Page

13521

Last Page

13525

Required Publisher's Statement

© 2005 by The National Academy of Sciences of the USA

doi:10.1073/pnas.0506179102

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