Skip to Main Content
Recent climate warming forces contrasting growth responses of white spruce at treeline in Alaska through temperature thresholdsAuthor(s): Martin Wilmking; Glenn P. Juday; Valerie A. Barber; Harold S.J. Zald
Source: Global Change Biology. 10: 1724-1736
Publication Series: Scientific Journal (JRNL)
PDF: View PDF (3.1 MB)
DescriptionNorthern and high-latitude alpine treelines are generally thought to be limited by available warmth. Most studies of tree-growth-climate interaction at treeline as well as climate reconstructions using dendrochronology report positive growth response of treeline trees to warmer temperatures. However, population-wide responses of treeline trees to climate remain largely unexamined. We systematically sampled 1,558 white spruce at 13 treeline sites in the Brooks Range and Alaska Range. Our findings of both positive and negative growth responses to climate warming at treeline challenge the widespread assumption that arctic treeline trees grow better with warming climate. High mean temperatures in July decreased the growth of 40 percent of white spruce at treeline areas in Alaska, whereas warm springs enhance growth of additional 36 percent of trees and 24 percent show no significant correlation with climate. Even though these opposing growth responses are present in all sampled sites, their relative proportion differs among sites, and there is no overall clear relationship between growth response and landscape position within a site. Growth increases and decreases appear in our sample above specific temperature index values (temperature thresholds), which occurred more frequently in the late 20th century. Contrary to previous findings, temperature explained more variability in radial growth after 1950. Without accounting for these opposite responses and temperature thresholds, climate reconstructions based on ring width will miscalibrate past climate, and biogeochemical and dynamic vegetation models will overestimate carbon uptake and treeline advance under future warming scenarios.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- 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.
CitationWilmking, Martin; Juday, Glenn P.; Barber, Valerie A.; Zald, Harold S.J. 2004. Recent climate warming forces contrasting growth responses of white spruce at treeline in Alaska through temperature thresholds. Global Change Biology. 10: 1724-1736
KeywordsAlaska, carbon uptake, climate change, cluster analysis, dendrochronology, threshold effects, treeline, white spruce
- Nonlinear responses of white spruce growth to climate variability in interior Alaska
- White spruce meets black spruce: dispersal, postfire establishment, and growth in a warming climate
- Consistent negative temperature sensitivity and positive influence of precipitation on growth of floodplain Picea glauca in Interior Alaska
XML: View XML