Ecology Letters, (2011) doi:10.1111/j.1461-0248.2011.01598.x LETTER Changes in forest productivity across Alaska consistent with

• Main Authors: Pieter S. A. Beck, Glenn P. Juday, Claire Alix, Valerie A. Barber, Stephen E. Winslow, Emily E, Patricia Heiser, James D, Scott J. Goetz
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: drought; evergreen forests; global warming; high latitudes; NDVI; productivity; remote sensing; tree rings. Ecology Letters (2011; Tundra; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.419.3725; http://www.lter.uaf.edu/pdf/1518_Beck_Juday_2011.pdf

Global vegetation models predict that boreal forests are particularly sensitive to a biome shift during the 21st century. This shift would manifest itself first at the biomeÕs margins, with evergreen forest expanding into current tundra while being replaced by grasslands or temperate forest at the biomeÕs southern edge. We evaluated changes in forest productivity since 1982 across boreal Alaska by linking satellite estimates of primary productivity and a large tree-ring data set. Trends in both records show consistent growth increases at the boreal–tundra ecotones that contrast with drought-induced productivity declines throughout interior Alaska. These patterns support the hypothesized effects of an initiating biome shift. Ultimately, tree dispersal rates, habitat availability and the rate of future climate change, and how it changes disturbance regimes, are expected to determine where the boreal biome will undergo a gradual geographic range shift, and where a more rapid decline.