Relationships of Site Characteristics to Vegetation in Canyon Grasslands of West Central Idaho and Adjacent Areas

Abstract

The relation of vegetation types to soil and other site characteristics was examined for 57 sample plots representing the Pacific Northwest Bunchgrass Region. Three series characterized by Carex spp., Festuca idahoensis, and Agropyron spicatum respectively, and 5 habitat types comprised the vegetation units. These were compared to their associated soil taxa (soil families) and to a group of individual soil and other site characteristics. Relationship to soil taxa was relatively weak, with several soil families associated with each of 4 of the habitat types. Strong relationship of vegetation types to 13 individual soil and site factors was shown by means of stepwise discriminant analysis. Reclassification by these site factors resulted in 92% concurrence with habitat types and even higher agreement with vegetation series. Site factors showing the highest degree of relationship with vegetation units were: elevation, radiation index, color (value), and organic matter of the "A" horizon, and lime depth. This method of relating individual site factors to vegetation provides a powerful tool for testing the validity of ecosystems recognized by vegetation, and should be useful also in categorizing sites where plant cover has been disturbed.