Terrestrial Ecosystem Classification in the Rocky Mountians, Northern Utah
Kusbach, A.. 2010. Utah State University
Abstract
Currently, there is no comprehensive terrestrial ecosystem classification for the
central Rocky Mountains of the United States. A comprehensive classification of
terrestrial ecosystems in a mountainous study area in northern Utah was developed
incorporating direct gradient analysis, spatial hierarchy theory, the zonal concept, and
concepts of diagnostic species and fidelity, together with the biogeoclimatic ecosystem
classification approach used in British Columbia, Canada.
This classification was derived from vegetation and environmental sampling of both
forest and non-forest ecosystems. The SNOwpack TELemetry (SNOTEL) and The
National Weather Service (NWS) Cooperative Observer Program (COOP) weather
station network were used to approximate climate of 163 sample plots.
Within the large environmental diversity of the study area, three levels of ecosystem
organization were distinguished: (1) macroclimatic %u2013 regional climate; (2) mesoclimatic,
accounting for local climate and moisture distribution; and (3) edaphic - soil fertility.
These three levels represent, in order, the L 1, L, and L-1 levels in a spatial hierarchy.
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Based on vegetation physiognomy, climatic data, and taxonomic classification of
zonal soils, two vegetation geo-climatic zones were identified at the macroclimatic (L 1)
level: (1) montane zone with Rocky Mountain juniper and Douglas-fir; and (2) subalpine
zone with Engelmann spruce and subalpine fir as climatic climax species.
A vegetation classification was developed by combining vegetation samples (releves)
into meaningful vegetation units.
A site classification was developed, based on dominant environmental gradients
within the subalpine vegetation geo-climatic zone. Site classes were specified and a site
grid was constructed. This site classification was coupled with the vegetation
classification. Each plant community was associated with its environmental space within
the site grid. This vegetation-site overlay allowed ecosystems to be differentiated
environmentally and a structure, combining zonal, vegetation, and site classifications,
forms a comprehensive ecosystem classification.
Based on assessment of plant communities' environmental demands and site
vegetation potential, the comprehensive classification system enables inferences about
site history and successional status of ecosystems. This classification is consistent with
the recent USDA, Forest Service ECOMAP and Terrestrial Ecological Unit Inventory
structure and may serve as a valuable tool not only in vegetation, climatic, or soil studies
but also in practical ecosystem management.
