Alpine and Subalpine Vegetation Chronosequences following Deglaciation in Coastal Alaska

Glacial recession is a major process in terrestrial ecosystems of the world and an obvious result of global warming Here we describe the alpine (above tree line) and subalpine forested and wetland/peatland vegetation chronosequences in Glacier Bay National Park and Preserve, Alaska We derived the results from three products (1) 4 deglaciation map of 50,000-, 13,000, and 1 to 246-year-old (Neoglacial) surfaces, (2) a landcover map, and (3) a plant association classification For the alpine chronosequence, Neoglactal surfaces are dominated by the tall shrub (>1 5 m) (Alnus and Salix), dwarf shrub (<0 1 m) (Salix and Dryas), and mesic herbaceous landcover classes These landcover classes also dominate the 13,000- and 50,000-year-old surfaces but dwarf shrub dominance changes to ericaceous The subalpine forested chronosequence consists of Populus balsamifera ssp trichocarpa and Picea sitchensis classes dominating the mid- and late seral Neoglacial surfaces, then Tsuga mertensiana and Picea sitchensis classes dominating the 13,000- and 50,000-year-old surfaces Wetlands/peatlands are rare on the Neoglacial and 13,000-year-old surfaces but common on the 50,000-year-old surface Alnus is rare on the 50,000-year-old surface yet common on the 13,000-year-old surface and, we speculate, is a relict from the end of the Pleistocene