Great Basin Naturalist


Plant communities are inherently variable due to a number of environmental and biological forces. Canopy cover and aboveground biomass were determined for understory vegetation in plant communities of a prairie grassland–forest ecotone in southeastern Montana. Vegetation units were described using polar ordination and stepwise discriminant analysis. Nine of a total of 88 plant species encountered and cover of litter were the most useful variables in distinguishing among vegetation units on the study area and accounted for nearly 100 percent of the variation in the data. Seven vegetation units were different (P < 0.05) after all 10 variables had been entered into the analysis. Some plant communities were represented by two or three different vegetation units, indicating that some plant communities were variable and nonuniform in botanical composition over a relatively small area. This variability will influence management practices for these areas. Multiple-use management will benefit by recognition of inherent plant community variation.