biogeoclimatic zones of b.c

• Bunchgrass
  
  
  
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Range

The Bunchgrass Zone covers less than one percent of the total area of British Columbia. This zone consists mostly of narrow patches of land centered on the major river valleys of the Okanagan, Thompson and Fraser river basins. It is situated in the rainshadow of the Coast and Cascade Mountains. In these areas, the zone occurs from the valley bottom up to elevations of approximately 900m on the valley slopes.

Coast Mountains

Climate

Because it is situated in a rainshadow, the Bunchgrass Zone includes some of British Columbia’s warmest and driest areas. Summer temperatures range from warm to hot, becoming cooler to the north and west and winters are moderately cold. Precipitation is low and the snowpack is rarely over 50cm. Peak periods of precipitation occur in the early winter and again in June and many sites are without snow for most of the winter, especially on southern aspects and wind-exposed sites. Because of low precipitation, and high temperatures in the summer, soils are only moist for a short period during the growing season, making conditions harsh for vegetation.

Vegetation

Summer droughts are too severe for trees to become established; as a result, grasses form the dominant vegetation cover. Widely spaced bunchgrass, particularly bluebunch wheatgrass, are characteristic of the native, undisturbed vegetation. Drought-tolerant shrubs and other types of grass like needle-and-thread grass, junegrass and Sandberg’s bluegrass are also common to the zone.
Differences in soil moisture largely control differences in plant communities from one area to the next. Ponderosa Pine and Douglas-fir forests occur on steep rocky soils on gravelly terraces and in cool, moist ravines. Moist shallow depressions often contain porcupine grass and Kentucky bluegrass while sand dunes , which are scattered throughout the zone, support scattered clumps of Indian ricegrass and sand dropseed. Cattails and bulrushes dominate in the marshes, which are a common form of wetland in the Bunchgrass Zone.

Bunchgrass                Bluegrass

Wildlife

Although the Bunchgrass Zone is one of the smallest zones in British Columbia, its unique mosaic of grassland, shrubs, moist and wet ecosystems, and dry, open forests supports a tremendous diversity of wildlife. The Burrowing Owl and short-horned lizard reach their northern breeding limits here and other species like the Snowy Owl and Gyrfalcon spend their summers far to the north but overwinter in the zone’s open grasslands. Grassland and shrub ecosystems provide habitats for a variety of birds, reptiles, amphibians, and mammals like Rocky Mountain elk, California bighorn sheep and mule deer. Forests provide habitat for species like the white-headed woodpecker, Townsend’s big-eared bat, and yellow-pine chipmunk. Riparian woodlands support populations of wood duck, American kestrel and water shrew. All ecosystems in this zone provide habitat for a diversity of invertebrates such as insects and spiders, including a large number of species that occur nowhere else in the province like the tiger beetle.

Mule Deer                  Big-eared bat           Rocky Mountain Elk

Resources

Fertile valley bottoms and warm growing seasons provide ideal conditions for many agricultural crops especially in the south where winters are less severe. The most common crops are tree fruits, grapes, alfalfa and ginseng. The warm, dry climate and large lakes and rivers provide opportunities for many outdoor recreational activities like water sports, wildlife viewing, and hiking.

Eneas Lake