Classification Distribution Vegetation Accuracy

Tree canopy is less than 10% (or absent), shrub cover is less than 25%, and herbaceous cover is greater than 25%. Vegetation is terrestrial (not submerged, floating, or growing in permanent water). Site is dry to mesic with little to no standing water. The class is comparable to the Viereck et al. (1992) hierarchical levels dry graminoid herbaceous (IIIA1), mesic graminoid herbaceous (IIIA2), dry forb herbaceous (IIIB1), and mesic forb herbaceous (IIIB2). The photo on the left is from the south side of the Alaska Range, and the photo on the right is a moist depression in the northwest region of Denali National Park and Preserve.

The dry-mesic herbaceous class is a minor class that occurs throughout the park under a variety of site conditions. It primarily occurs as rich herbaceous meadows on mesic sideslopes ranging up to >50% slope and river terraces on the south side of the Alaska Range. The class occurs both above the alder zone up to 1,200 meters, and mixed in with alder moving down slope (Table 3). On the landcover map, it is underrepresented on the south side of the Alaska Range due to its partial inclusion in the herbaceous-shrub class. It also occurs as grassy meadows, dominated by Calamagrostis canadensis, found on low elevation moist, and periodically wet, depressions within the boreal forest in the northwestern portion of the park. These sites are moist, however, standing water may be present in small amounts seasonally. Tussock tundra, dominated by Eriophorum species, also forms a portion of this class occurring as small patches on gentle to moderate slopes of foothills and broad valleys bordering the Kantishna Hills and the north side of the Alaska Range, and also on hills near Lake Minchumina. Tussock tundra soils are mesic with tussocks of organic matter and live vegetation over mineral soil. Small seasonal pools of water are often found between the tussocks. The dry-mesic herbaceous class nearly always occurs as small patches within a mosaic of other classes. Most landcover classes occur adjacent to the class due to its wide geographic distribution and elevation range. It is uncommon in most ecoregions except the Alaska Range-south-central mountains and valleys ecoregion (Tables 4a and 4b; Clark 1998), and covers 0.8% (45,684 acres) of Denali National Park and Preserve (Table 5).

The dry-mesic herbaceous class is a grouping of plant associations that encompasses dry or mesic sites as well as lush herbaceous meadows. Herbaceous meadows contain such forbs as Veratrum viride, Ligusticum scoticum, Geranium erianthum, Cicuta douglasii, Iris setosa, Athyrium filix-femina, Calamagrostis canadensis, Epilobium angustifolium, Heracleum lanatum and Sanguisorba stipulata. Total cover often exceeds 90%. Low shrubs may also occur including Spiraea beauverdiana and Salix planifolia. The grassy meadows in the boreal forest are dominated by Calamagrostis canadensis with cover values up to 95%. Other species present but uncommon are Betula glandulosa, Vaccinium uliginosum, Athyrium filix-femina and Myrica gale.Sites that are dominated by tussocks have high levels of graminoids, predominantly Eriophorum species, and mosses. Surface water, Betula nana, and Rubus chamaemorus also occur. Tussock cover ranges up to 90% on sites sampled.

The producer’s accuracy for the dry-mesic herbaceous class is 70.0%, with a user’s accuracy of 85.6%. Most of the errors of omission and commission are with the low shrub birch-ericaceous-willow, herbaceous-shrub and dwarf shrub classes.