Lea, T. 2008. Historical (pre-settlement) ecosystems of the Okanagan Valley and Lower Similkameen Valley of British Columbia – pre-European contact to the present. Davidsonia 19(1):3-36

A series of maps compare the 1800, 1938 and 2005 ecosystems in the Okanagan and Lower Similkameen Valleys. Much of the gentle slope valley bottom ecosystems have been replaced by urban and agricultural development. Analysis of the areal extent of historical and remaining areas has been done for specific ecosystem types that are important for many species at risk and are themselves ecosystems at risk. These include: Douglas-fir – pine-grass gentle slope; Ponderosa pine – bluebunch wheatgrass gentle slope; water birch – red-osier dogwood wetland riparian shrub; black cottonwood – red-osier dogwood floodplain; the Okanagan River ecosystem; cattail marsh; Idaho fescue – bluebunch wheat-grass grassland; big sagebrush shrub-steppe and antelope-brush – needle-and-thread grass shrub-steppe. For two of these ecosystems, over 90 percent of the original ecosystem has been lost.

Uses of this mapping for conservation of species at risk are presented, including applications to status assessment, quantification of threats, informing restoration projects, and providing data on the importance of the remaining areas of ecosystems that have been severely depleted. The paper concludes that it is important to focus on conservation of ecosystems in order to maintain species at risk.