Title: Variation in carbohydrate source-sink relations of forest and treeline white spruce in southern, interior and northern Alaska
Author: Sveinbjornsson, Bjartmar; Smith, Matthew; Traustason, Tumi; Ruess, Roger W.; Sullivan, Patrick F.
Source: Oecologia. 163: 833-843
Description: Two opposing hypotheses have been presented to explain reduced tree growth at the treeline, compared with growth in lower elevation or lower latitude forests: the carbon source and sink limitation hypotheses. The former states that treeline trees have an unfavorable carbon balance and cannot support growth of the magnitude observed at lower elevations or latitudes, while the latter argues that treeline trees have an adequate carbon supply, but that cold temperatures directly limit growth. In this study, we examined the
relative importance of source and sink limitation in forest and treeline white spruce (Picea glauca) in three mountain ranges from southern to northern Alaska. We related seasonal changes in needle nonstructural carbohydrate (NSC) content with branch extension growth, an approach we argue is more powerful than using needle NSC concentration. Branch extension growth in the southernmost Chugach Mountains was much greater than in the White Mountains and the Brooks Range. Trees in the Chugach Mountains showed a greater seasonal decline in needle NSC content than trees in the other mountain ranges, and the seasonal change in NSC was correlated with site-level branch growth across mountain ranges. There was no evidence of a consistent difference in branch growth between the forest and treeline sites, which differ in elevation by approximately 100 m. Our results point to a continuum between source and sink limitation of growth, with high-elevation trees in northern and interior Alaska showing greater evidence of sink limitation, and those in southern Alaska showing greater potential for source limitation.
Keywords: growth, nonstructural carbohydrates, Picea glauca, temperature, treeline
View and Print this Publication (1.28 MB)
- 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.
- You may send email to firstname.lastname@example.org to request a hard copy of this publication. (Please specify exactly
which publication you are requesting and your mailing address.)
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility
Sveinbjornsson, Bjartmar; Smith, Matthew; Traustason, Tumi; Ruess, Roger W.; Sullivan, Patrick F. 2010. Variation in carbohydrate source-sink relations of forest and treeline white spruce in southern, interior and northern Alaska. Oecologia. 163: 833-843.