Barber, Valerie A.

7 items:

Reduced growth of Alaskan white spruce in the twentieth century from temperature-induced drought stress Categories: Data, Publication; Types: Citation, Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: R1-Vulnerability Forest Species and Communities to Climate Change
Recent climate warming forces contrasting growth responses of white spruce at treeline in Alaska through temperature thresholds Northern 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 1558 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... Categories: Data, Publication; Types: Citation, Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: P2-Changes in Plant and Animal Species Due to Climate Change, R1-Vulnerability Forest Species and Communities to Climate Change
Changes in forest productivity across Alaska consistent with biome shift 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 biome?s margins, with evergreen forest expanding into current tundra while being replaced by grasslands or temperate forest at the biome?s 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... Categories: Data, Publication; Types: Citation, Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: R1-Vulnerability Forest Species and Communities to Climate Change
Modeling spatial variability of white spruce (Picea glauca) growth responses to climate change at and below treeline in Alaska - a case study from two national parks Categories: Data, Publication; Types: Citation, Downloadable, Map Service, OGC WFS Layer, OGC WMS Layer, Shapefile; Tags: P2-Changes in Plant and Animal Species Due to Climate Change
Holocene climate change and carbon cycling in a groundwater-fed, boreal forest lake: Dune Lake, Alaska Issue Title: Special issue: "Holocene paleoenvironmental records from Arctic lake sediment" Opal, organic C and N contents, and organic δ^sup 13^C and δ^sup 15^N stable isotopes were analyzed on a sedimentary sequence spanning the past ~12,000 years from Dune Lake, a shallow groundwater-fed lake in the boreal forest region of central interior Alaska. The chronology, based on ^sup 210^Pb and 15 AMS radiocarbon dates on terrestrial materials, indicates that 5 m of biogenic sediment accumulated following dune stabilization at ~10,000 cal yr BP. Previous studies on lake level and pollen were synthesized with these data to assess Holocene changes in hydrogeology and climate. Variability in groundwater level and flux... Categories: Publication; Types: Citation; Tags: Paleo and Holocene

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