Classification Distribution Vegetation Accuracy

The sparse vegetation landcover class refers to sites with 15% to 24% total vegetation cover.

The sparse vegetation class is common in alpine areas of the Alaska Range. It is generally found on unstable to stable upslope bedrock and unconsolidated rock in the mountains and high mountain valley floors. This class also occurs on sandbars, alluvial fans and the debris covered surfaces of glaciers. The physical site characteristics are similar to the dwarf shrub-rock class however it has a much higher surface rock and mineral soil component. The slope ranges up to >50%, and the elevation ranges up to 1,142 meters based on field data, however, the spectral map places the maximum elevation at 4,527 meters (Table 3). The soils are a thin layer of dry to mesic sand, litter or organic matter. The sparse vegetation typically occurs as patches on the organic matter interspersed with exposed rock. This class is common in the Alaska Range-high mountains, Alaska Range-interior mountains and valleys, and Alaska Range-south-central mountains and valleys ecoregions (Tables 4a and 4b; Clark 1998). The sparse vegetation landcover class covers 4.8% (289,308 acres) of Denali National Park and Preserve (Table 5). The class frequently occurs next to the bare ground, dwarf shrub-rock and dwarf shrub classes.

The sparse vegetation class is dominated by dwarf shrubs, primarily Dryas octopetala, surface rock, and exposed mineral soil. Other dwarf shrubs include Dryas integrifolia, Salix reticulata, S. arctica, S. phlebophylla, Cassiope tetragona, Vaccinium uliginosum, Arctostaphylos rubra, and A. alpina. Forbs include Epilobium angustifolium, Aster species, Heracleum lanatum, Veratrum viride, Anemone narcissiflora, and Campanula species.

The producer’s accuracy for the sparse vegetation class is 87.6%, with a user’s accuracy of 45.7%. Most of the errors of omission and commission are with the bare ground and dwarf shrub-rock map classes.