The Similkameen has long been recognized as a region that combines a tremendous diversity of habitats with unique species, many of which are found nowhere else in British Columbia or elsewhere in Canada. The Similkameen and Okanagan Valley also has more species of plants and animals living here than in most areas of BC or Canada. But it is now one of the four most endangered ecosystems in Canada. The unique characters of this ecosystem are centred on the low elevation grasslands and dry forests, habitat areas most desired to use for agriculture or housing.
The low elevation grasslands cover about one quarter of the South Okanagan landscape, but 81 percent of the agricultural and urban developments have taken place here. These developments have altered more than 60 percent of the grasslands and shrub habitats of this zone, and only 9 percent are in a relatively undisturbed state. Roughly 85 percent of wetland and stream-side habitats have been lost.
The South Okanagan and Lower Similkameen area
The South Okanagan ecosystem area extends over a land area of approximately 159,000 hectares from Naramata and Summerland south to the United States border and east to Keremeos.
The southern end of the Okanagan Valley in Canada represents the northernmost extension of the Western Great Basin of North America. Low annual precipitation, hot summers, and mild winters create a varity of semi-arid habitats. The dry grasslands and open pine forests of the Okanagan have served as a vital landscape corridor between the shrub-steppe habitats of the Columbia Basin in Washington and Oregon and the grasslands of the Thompson and Nicola valleys to the north and west.
The area lies within the Southern Interior Ecoprovince, the only ecoprovince in British Columbia that is part of the Dry Ecodomain and Semi-arid Steppe Highland Ecodivision.
The Okanagan Valley lies like the neck of an hourglass between the vast boreal forests to the north and the Great Basin deserts to the south. This critical position, when combined with the altitudinal range in the valley, the chain of large lakes, and the flow of moist air off the Pacific at high elevations, produces an abundance of animal and plant species found in few other places in Canada or even North America.
Desert-like grasslands in the valley bottom are bordered on one side by rich marshes and moist cottonwood and birch woodlands, on the other by towering cliffs and hillsides covered with ponderosa pine forests. As you move upward, these forests change to Douglas-fir, larch, lodgepole pine, spruce and subalpine fir, and finally to alpine tundra.
Many species reach their southern or northern limits in the Okanagan. Populations at the end of their species' ranges are usually genetically diverse, since they are meeting greater challenges in habitat, climate and competitors. This genetic diversity is very important to the overall health of species' populations, and is critical to their survival in times of environmental change; it is also an integral part of the biodiversity of the Okanagan.
Thus, the Okanagan has long been recognized as a site that combined a tremendous diversity of life with an impressive list of species. About 190 species of birds breed in the Okanagan. Not only is this almost half the Canadian total, but it is probably the highest total for any area of similar size in Canada, and close to the highest in United States and Canada.