Big sagebrush ecosystems are widespread throughout the western United States and provide essential ecosystem services, including nutrient cycling and habitat for sagebrush obligate taxa, such as the greater sage grouse. Sagebrush habitat has experienced a 45% reduction in range and most intact habitat is at risk from a variety of factors. While restoration practitioners generally attempt to restore ecosystems to historic conditions, this is not always achievable if historical reference conditions are not well defined and we lack knowledge of ecological variability. The use of functional types (FTs), rather than specific species, to restore ecosystem structure and function may be easier to achieve but is not well tested. We examined the variability of vegetation communities along a sagebrush elevation gradient in Dinosaur National Monument, CO. We classified 1245 plots based on species cover and aligned that classification with USNVC types. We then performed several FT analyses in PCORD with 517 plots to examine differences in functional dominants among classified groups and relationships among FTs and environment. We asked: (1) Do functional dominants differ along this elevation gradient?; and (2) can we use functional types to refine restoration protocols, such as seed mixes?
Results/Conclusions
Plots were classified into nine groups based on dominant species, and a follow-up NMS ordination clearly discriminate groupings in ordination space. The data further show a relationship with the environmental variables of temperature and variation in temperature (increasing to the upper left quadrant), and elevation and moisture (decreasing to the lower right quadrant); an elevation gradient. When a similar analysis was conducted on a functional type matrix (including growth form, clonal organ, photosynthetic pathway and life history), distinctions among groups were not clear; the convex hulls have a great deal of overlap and the Basin Big Sagebrush community has an extremely wide distribution. However, we did find some significant differences in functional diversity and functional dispersion among groups. Mean cover of different function types suggest minor differences among groups, but worth noting when developing seed mixes. Differences in the dominance of clonal growth organs was clear, and clonal plants made up 50% -100% of the cover for nearly all groups. For sagebrush communities alone, A. nova sites are not even shrub-dominated, perennial and annual graminoids are more common in Wyoming Big Sagebrush than Basin Big Sagebrush, and Mountain Big Sagebrush communities seem strongly dominated by that one species.