Skip booklet index and go to page content

Technical Thematic Report No. 11. - Western Interior Basin Ecozone+ Evidence for key findings summary

Key Findings at a Glance: National and Ecozone+ Level

Table 2 presents the national key findings from Canadian Biodiversity: Ecosystem Status and Trends 2010 Footnote 3 together with a summary of the corresponding trends in the Western Interior Basin Ecozone+ (WIBE). Topic numbers refer to the national key findings in Canadian Biodiversity: Ecosystem Status and Trends 2010. Topics that are greyed out were identified as key findings at a national level but were either not relevant or not assessed for this ecozone+ and do not appear in the body of this document. Evidence for the statements that appear in this table is found in the subsequent text organized by key finding. See the Preface on page i.

Top of Page

Table 2: Key findings overview

2.1 Theme: Biomes
Themes and topicsKey Findings: NationalKey Findings: Western Interior Basin Ecozone Table Footnote a
1. ForestsAt a national level, the extent of forests has changed little since 1990; at a regional level, loss of forest extent is significant in some places. The structure of some Canadian forests, including species composition, age classes, and size of intact patches of forest, has changed over longer time frames.Forests cover 73% of the WIBE. Intact forests larger than 100 km2 cover 22%, largely in the mountainous western portion. The extent of lower elevation forests declined between 1800 and 2005; for example, Douglas-fir ecosystems declined by 27% and ponderosa pine ecosystems by 53%.
2. GrasslandsNative grasslands have been reduced to a fraction of their original extent. Although at a slower pace, declines continue in some areas. The health of many existing grasslands has also been compromised by a variety of stressors.Grasslands cover 2% of the WIBE. Although the rate of loss has slowed since 1990, 16% of grasslands were lost to development between 1850 and 2005. Grasslands outside of protected areas are at risk of conversion to agricultural, commercial, and residential uses. Stressors that compromise grasslands in the WIBE include invasive species and fire suppression.
3. WetlandsHigh loss of wetlands has occurred in southern Canada; loss and degradation continue due to a wide range of stressors. Some wetlands have been or are being restored.Wetlands occupy <1% of the WIBE. Between 1800 and 2005, 85% of low-elevation wetlands were lost. Wetlands continue to be lost and degraded by urbanization, intensive agriculture, and, in some areas, heavy recreational use. In addition, invasive species and climate change pose serious threats.
4. Lakes and riversTrends over the past 40 years influencing biodiversity in lakes and rivers include seasonal changes in magnitude of stream flows, increases in river and lake temperatures, decreases in lake levels, and habitat loss and fragmentation.Lakes, rivers, and streams cover 2% of the WIBE. There are high demands on scarce water supplies. Lake level fluctuations, tributary stream habitat loss, changes in nutrient levels, and an invasive shrimp have altered Okanagan Lake. Most Okanagan streams and headwater lakes have been dammed. Although 1 km is being restored, 93% of the Okanagan River was altered by channelization.
5. CoastalCoastal ecosystems, such as estuaries, salt marshes, and mud flats, are believed to be healthy in less-developed coastal areas, although there are exceptions. In developed areas, extent and quality of coastal ecosystems are declining as a result of habitat modification, erosion, and sea-level rise.Not relevant
6. MarineObserved changes in marine biodiversity over the past 50 years have been driven by a combination of physical factors and human activities, such as oceanographic and climate variability and overexploitation. While certain marine mammals have recovered from past overharvesting, many commercial fisheries have not.Not relevant
7. Ice across biomesDeclining extent and thickness of sea ice, warming and thawing of permafrost, accelerating loss of glacier mass, and shortening of lake-ice seasons are detected across Canada's biomes. Impacts, apparent now in some areas and likely to spread, include effects on species and food webs.Glaciers in the Bridge River Basin retreated by 8 km2 (7%) between 1995 and 2005 and Place Glacier experienced a 37-metrereduction of ice thickness from 1964 to 2008.

Top of Page

2.2 Theme: Human/Ecosystem Interactions
Themes and topicsKey Findings: NationalKey Findings: Western Interior Basin Ecozone Table Footnote a
8. Protected areasBoth the extent and representativeness of the protected areas network have increased in recent years. In many places, the area protected is well above the United Nations 10% target. It is below the target in highly developed areas and the oceans.In 2009, 5,000 km2 (9%) of the WIBE was federally or provincially protected. The Interior Dry Plateau natural region, characterized by the South Okanagan and Lower Similkameen, is unrepresented in the national park system.
9. StewardshipStewardship activity in Canada is increasing, both in number and types of initiatives and in participation rates. The overall effectiveness of these activities in conserving and improving biodiversity and ecosystem health has not been fully assessed.Many organizations, agencies, and groups are involved in stewardship activities in the WIBE. In the South Okanagan, covenants, conservation organizations, and landowners care for 13% of the shrub-steppe and wetland/riparian habitats that occur on private lands. There are no syntheses of participation rates or stewardship activities for the WIBE.
Ecosystem conversion Table Footnote aEcosystem conversion was initially identified as a nationally recurring key finding and information was subsequently compiled and assessed for the WIBE. In the final version of the national report, Footnote 3 information related to ecosystem conversion was incorporated into other key findings. This information is maintained as a separate key finding for the WIBE.Ecosystem conversion and fragmentation are the primary threats to biodiversity in the WIBE. Historically, most high-value riparian and wetland ecosystems and a substantial portion of low elevation grassland/shrubland ecosystems were converted to other uses. From 1991–2001, >22% of low elevation habitats were converted. The WIBE also has the second highest road density (1.7 km of road/km2) among the 10 regions of BC.
10. Invasive non-native speciesInvasive non-native species are a significant stressor on ecosystem functions, processes, and structure in terrestrial, freshwater, and marine environments. This impact is increasing as numbers of invasive non-native species continue to rise and their distributions continue to expand.Impacts of invasive non-native species in the WIBE include lowered real estate values, reduced quality of fish habitat, displaced native species, clogged irrigation pipes, decreased quality of forage for wildlife and livestock, and reduced recreational opportunities. Biological, chemical, and mechanical control are used to manage the priority invasives among the hundreds of non-native species that have been recorded in the WIBE.
11. ContaminantsConcentrations of legacy contaminants in terrestrial, freshwater, and marine systems have generally declined over the past 10 to 40 years. Concentrations of many emerging contaminants are increasing in wildlife; mercury is increasing in some wildlife in some areas.In the 1990s, increased contaminant levels were detected in osprey downstream from a pulp mill and in American robins in orchards. In contrast, mercury and DDT were within concentrations considered safe for human consumption for fish from Okanagan Lake.
12. Nutrient loading and algal bloomsInputs of nutrients to both freshwater and marine systems, particularly in urban and agriculture-dominated landscapes, have led to algal blooms that may be a nuisance and/or may be harmful. Nutrient inputs have been increasing in some places and decreasing in others.The WIBE is the only agricultural ecozone+ in Canada where the residual soil nitrogen decreased from 1981 to 2006. Nutrient loading in several of the Okanagan Valley lakes, such as Skaha and Osoyoos, declined from the early 1970s to 2001 due to reductions in nutrient loading from agricultural sources and sewage treatment plants.
13. Acid depositionThresholds related to ecological impact of acid deposition, including acid rain, are exceeded in some areas, acidifying emissions are increasing in some areas, and biological recovery has not kept pace with emission reductions in other areas.The soils and lakes in the WIBE are thought to be at low risk of any small changes in rain pH, so acid deposition is not considered to be a concern for this ecozone+.
14. Climate changeRising temperatures across Canada, along with changes in other climatic variables over the past 50 years, have had both direct and indirect impacts on biodiversity in terrestrial, freshwater, and marine systems.From 1950 to 2007, the temperature in the WIBE increased at most times of the year. Precipitation increased in spring and fall whereas snow decreased. The seasonality of stream flow changed, with earlier onsets of spring freshets, lower flows in late summer, and higher flows in winter.
15. Ecosystem servicesCanada is well endowed with a natural environment that provides ecosystem services upon which our quality of life depends. In some areas where stressors have impaired ecosystem function, the cost of maintaining ecosystem services is high and deterioration in quantity, quality, and access to ecosystem services is evident.Ecosystem services in the WIBE include water, crop pollination, and nutrient cycling which are necessary for food production and potable water. Other services include forests, wildlife, and fish, which are harvested either commercially or recreationally. Although ecosystem services have not been quantified for the WIBE, a project to estimate the value of ecosystem services supported by the last remaining natural section of the Okanagan River was initiated in 2012/13.

Top of Page

2.3 Theme: Habitat, Wildlife, and Ecosystem Processes
Themes and topicsKey Findings: NationalKey Findings: Western Interior Basin Ecozone Table Footnote a
16. Agricultural landscapes as habitatThe potential capacity of agricultural landscapes to support wildlife in Canada has declined over the past 20 years, largely due to the intensification of agriculture and the loss of natural and semi-natural land cover.Agricultural lands in the WIBE are dominated by Unimproved Pasture (67% in 2006), which provides breeding and feeding habitat for 80 species of wildlife. However, average wildlife habitat capacity on agricultural land declined from 70% to 61% between 1986 and 2006.
17. Species of special economic, cultural, or ecological interestMany species of amphibians, fish, birds, and large mammals are of special economic, cultural, or ecological interest to Canadians. Some of these are declining in number and distribution, some are stable, and others are healthy or recovering.The WIBE is ecologically unique in Canada as the northern extension of the Great Basin Desert. It has high species richness and assemblages of plants and animals that occur nowhere else in Canada. It also has a large number of species and ecosystems of conservation concern. Several bird and fish populations have declined over the past 30–40 years. Most ungulate and large carnivore populations are currently stable or increasing.
18. Primary productivityPrimary productivity has increased on more than 20% of the vegetated land area of Canada over the past 20 years, as well as in some freshwater systems. The magnitude and timing of primary productivity are changing throughout the marine system.Primary productivity increased for 16,713 km2(30.1%) and decreased for 1,035 km2(1.9%) of the WIBE between 1985 and 2006. The increases may be the result of regeneration in mixed forests; the reasons for the decreases are not known.
19. Invasive non-native speciesThe dynamics of natural disturbance regimes, such as fire and native insect outbreaks, are changing and this is reshaping the landscape. The direction and degree of change vary.In the 2000s, the burned area increased more than three-fold to >1,500 km2 (2.6%) of the ecozone+, possibly due to changing climate, increased fuel loads due to fire suppression prior to the 1990s, and the interaction between forest fires and outbreaks of insects. Mountain pine beetles peaked in 2008 when they affected 8,100 km2. In BC, western spruce budworms are found nearly exclusively in the WIBE where they peaked in 2007 affecting 3,800 km2.
20. Food websFundamental changes in relationships among species have been observed in marine, freshwater, and terrestrial environments. The loss or reduction of important components of food webs has greatly altered some ecosystems.Over the past 40 years, an invasive non-native shrimp altered food web dynamics in Okanagan Lake and contributed to the decline of native salmonids. A temporary decline in mule deer resulted in increased cougar predation on mountain goat in the 1990s. Populations of deer recovered quickly but mountain goats were slow to recover.

Top of Page

2.4 Theme: Science/Policy Interface
Themes and topicsKey Findings: NationalKey Findings: Western Interior Basin Ecozones Table Footnote a
21. Biodiversity monitoring, research, information management, and reportingLong-term, standardized, spatially complete, and readily accessible monitoring information, complemented by ecosystem research, provides the most useful findings for policy-relevant assessments of status and trends. The lack of this type of information in many areas has hindered development of this assessment.Ecosystem monitoring programs and research studies provide information on biodiversity for the WIBE. However, gaps include traditional and local ecological knowledge and data on contaminants. In addition, monitoring and research are unevenly distributed, with underrepresentation of the northern Okanagan.
22. Rapid change and thresholdsGrowing understanding of rapid and unexpected changes, interactions, and thresholds, especially in relation to climate change, points to a need for policy that responds and adapts quickly to signals of environmental change in order to avert major and irreversible biodiversity losses.Population declines of birds and fish, the loss of plant communities such as grasslands, and changes in water availability are evidence or indicators of abrupt or unexpected ecological change.

Top of Page

Table 2 Footnote

Footnote 1

This key finding is not numbered because it does not correspond to a key finding in the national report.

Return to Footnote a referrer


Content Footnote

Footnote 1

Federal, Provincial and Territorial Governments of Canada. 2010. Canadian biodiversity strategy: ecosystem status and trends 2010. Canadian Councils of Resource Ministers. Ottawa, ON. vi + 142 p.

Return to Footnote 3 référence