Vegetation Composition and Structure: Baseline Monitoring in the Southwest Alaska Network, 2009 Annual Summary Report

Miller, Amy; Walton, James; Moore, Claudette; Thompson, William

During the 2009 field season, we established thirty-three 0.25 hectare plots, sampling four vegetation types (spruce woodland; closed spruce forest (beetle kill); dwarf shrub tundra; treeline spruce) in low (0-450 m) and mid-elevation (450-900 m) bands in the interior of Katmai (GRTS plots). Three mid-elevation plots were collocated with the RAWS weather station above Lake Colville (elevation 470 m). Four closed spruce-beetle plots were established near Lake Colville, Lake Brooks, and the Bay of Isles (Naknek Lake). All beetle-affected stands had been cored in 2007 as part of a separate study examining historic spruce beetle activity. Additional tree cores were collected in 2009 to describe age and size-class structure of the stands, and to relate climate variables to growth characteristics (e.g., growth suppression) that preceded the recent beetle outbreak. Soil temperature loggers were installed at 1-2 sites in each vegetation type (eleven sites total) to monitor the timing and duration of freeze-thaw periods, snowpack development, and snowmelt. Plot variables were summarized within and across sites for the four vegetation types (closed spruce forest, spruce woodland, treeline, dwarf shrub). Species richness was highest at higher elevations (450-900 m), particularly at upper treeline, where species from low elevation forested communities and mid- to high elevation dwarf shrub and alpine communities co-occurred. Nonvascular species richness, as measured in nested frequency plots, was up to three times greater than for vascular species at a given site. Trees in spruce forest and spruce woodland sites ranged from less than 50 years to greater than 240 years in age. The oldest trees were found in mature forest affected by the spruce beetle, including stands on the east shore of Lake Colville (212 years) and the Valley of 10,000 Smokes Road (312 years). Treeline spruce ranged from approximately 20-60 years in age. Tree mortality ranged from 0%-45% in spruce woodland sites, and from 36%-98% in the beetle plots. Snag densities and fine fuel loads were highest in the beetle plots, but large woody debris loads did not differ between the woodland and closed forest (beetle) sites, nor did seedling densities, on average. A globally endangered lichen, Erioderma pedicellatum (Hue) P.M. Jørg, known from only two populations in North America, was found at one of the beetle-affected sites. A second rare lichen, Hypogymnia pulverata (Nyl.) Elix, was found at several additional locations in the park.