Vegetation and landscape ecologists at ACCS developed vegetation, wetland, and land cover maps to spatially describe the continuum of vegetation communities and geophysical characteristics for terrestrial and wetland landscapes across Alaska. Our approaches include both traditional non-overlapping discrete maps that depict exclusive vegetation types and novel continuous variation maps that represent the greatest amount of observed variation for plant species. Map products are used to assess the ecosystem status and trends. The vegetation ecology program has produced a composite landcover dataset that covers the entirety of Alaska by mosaicking the best available regional landcover data. At present, the Alaska Vegetation and Wetland Composite (AKVWC) provides the best spatial and ecological resolution land cover for cross-jurisdictional landscapes in Alaska. AKVWC classifies the landscape into standardized fine and coarse classes while maintaining the source classification in the attributes.
Continuous Foliar Cover and Community Mapping
Most existing spatial representations of vegetation depend on several assumptions that are never or rarely observed in reality: A.) individual species form deterministic clusters of multiple but finite discrete vegetation types; B.) spatial vegetation patterns do not vary quantitatively; and C.) transitions between vegetation types are always abrupt discontinuities. Qualitative and subjective discrete vegetation maps limit our ability to quantify species- or community-level distribution, abundance, trend, change, or relationship with ecological drivers. Non-overlapping grids of discrete, subjectively-defined vegetation types (i.e. typical vegetation and land cover maps) do not represent observed vegetation patterns and are not consistent with individualistic, niche-based ecological theory as they subjectively subsume broad ranges of multi-species response variation and imply abrupt environmental discontinuities where none exist.
The responses of individual species to environmental gradients drive variation in vegetation communities. Additionally, the individual responses of species to environmental gradients, including gradients of biotic interactions, form continuums in niche-space that drive species patterns in physical space. In combination, the theories of individualistic response and niche suggest that the species is the fundamental unit organizing vegetation patterns across landscapes along environmental gradients. At ACCS, vegetation ecologists are exploring novel continuous approaches to analyzing and mapping species-level foliar cover and plant communities.