| Summary: | An ecological classification of high elevation range provides a framework for proper resource management. Alpine and subalpine vegetation in the Southern Chilcotin Mountains was studied to characterize the plant communities of the high elevation rangelands in the southern interior of British Columbia. The impacts of grazing on the structure and composition of the vegetation were evaluated. Two hundred and thirty-nine sites were sampled in a 10,000 ha area. Plots were selected randomly within homogeneous units delineated on 1:30,000 (40 chain) air photos prior to the field season. These were classified on the basis of physiognomy, dominant species and environmental conditions. The following nineteen community types were described: Picea engelmanii-Abies lasiocarpa forest, Pinus albicaulis-Juniperus communis forest, Salix bare layi-Carex aquatilis shrub wetland, Salix barrattiana alpine shrub wetland, Salix brachycarpa-Salix barclayi shrubland, Salix brachycarpa-Festuca spp. shrubfieId, Salix brachycarpa-Phleum alpinum shrubfieId, Arctostaphylos uva-ursi-Amelanchier alnifolia dry shrubland, Salix cascadensis dwarf willow shrubland, Dryas octopetala fellfield, Dryas octopetala-Festuca altaica alpine grassland, Carex aquatilis/rostrata wetland, Carex nigricans late snowbed meadow, Festuca altaica-Festuca brachyphylla meadow, Festuca brachyphylla meadow, Festuca brachyphylla-Phleum alpinum meadow, Phleum alpinum-Carex phaeocephala meadow, Koeleria cristata dry meadow, and crustose lichen rock-land or talus terrain unit. Changes in the structure and composition of plant communities in response to grazing pressure were evident on the more heavily used valley bottom meadow community types. After many years of use, Festuca altaica appears to have, been eliminated from heavily grazed meadows, there is a decrease in the height of the vegetation, an increase in the exposed bare ground, and an increase in the abundance of weedy species in all community types. Many of the community types described from this region are floristically and/or ecologically comparable with plant communities described from other high elevation areas in British Columbia, the southern Yukon, and the Pacific Northwest of the United States. Land and Food Systems, Faculty of Graduate
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