Plant community – soil relationships in a topographically diverse grassland in southern interior British Columbia, Canada

Abstract

The current management focus for many of British Columbia’s grasslands is on sustaining their high natural and economic values in light of concerns over climate change and spread of exotic species. To that end, scientific information on plant community – soil – topographic relationships is required to assist with the often complex decisions that managers face. We collected data on vegetation, topography, and soil properties at 38 sites over a range of elevation zones and aspects at Lac du Bois Grasslands Provincial Park near Kamloops, British Columbia. Cluster analysis of the vegetation data validated the current three-zonal system used for grazing management but indicated that boundaries between adjacent plant communities are interspersed according to aspect. Principal component analysis (PCA) of environmental variables identified a gradient from the less productive, lower grasslands (higher soil bulk density, bare soil, coarse fragment content), to the more productive, upper grasslands (higher litter cover, total soil C and aggregate stability). Projection of six exotic species functional groups into the PCA-environment space showed significant associations of winter annuals with the lower grasslands, versus perennials (both clonal reproducers and seed bankers) with the upper grasslands. Our analysis showed promise in identifying fine-scale linkages between plant community patterns and key environmental factors. This approach may be useful as part of a proactive management plan for maintaining the health of British Columbia grasslands.