Ants of the South Okanagan Grasslands, British Columbia

Number 11, 2005 The South Okanagan grasslands are an extension of the intermontane grasslands of the Great Basin that extends from northern Mexico through the mid-western United States to the southern edge of the temperate forests in British Columbia (Pitt and Hooper 1994). Within the South Okanagan grasslands, the ecosystem of greatest importance to biodiversity conservation is the Antelope-brush (Purshia tridentata) shrub-steppe, 60% of which has been lost to agriculture and urban development (Schluter et al. 1995), and 9% remains in good natural condition (Redpath, 1990). This ecosystem occurs from valley bottoms to 700 m elevations, from Osoyoos in the south to Penticton in the north. The dominant plant in the ecosystem’s natural state is blue-bunch wheatgrass (Elymus spicatus [Agropyron spicatum]), followed by big sagebrush (Artemisia tridentata), both characteristic plants of bunchgrass ecosystems (Miedinger and Pojar 1991). Occurring on sandy soils, the main bunchgrasses are three-awn (Aristida longisita), needle-and-thread (Stipa coratea) and sand dropseed (Spirobolus cryptandrus). Douglas-fir and Ponderosa pine are sparse and wetlands are common in valley bottoms.