Importance to other wildlife
In addition to being important to waterfowl, the habitats in the Intermountain are valuable to other species as well. British Columbia is one of the most biologically diverse regions in North America and certainly the most biologically diverse province in Canada. Excluding marine fish, BC contains 732 species of vertebrates including 467 species of birds, 143 species of mammals, 19 species of reptiles, 20 species of amphibians, and 83 species of freshwater fish, many of which rely on habitats in the Intermountain. Nearly 300 species of birds breed in the province, 40 of which breed nowhere else in Canada. Furthermore, the province has 2,073 species of native plants of which nearly 20% are currently considered at risk. Most of the province’s threatened and endangered wildlife and plants are found in the grassland districts of the southern Intermountain.
Habitat characteristics, impacts and limitations
Although topography contributes to habitat diversity, we define 4 landscapes based on major land uses within the past 150 years, namely ranching, forestry, crop-based agriculture, and urbanization. These uses loosely define the following landscapes: Rangeland, Forestland, Agriculture/Forest Fringe, and Urban and Urban Fringe. Because land uses are not necessarily confined to specific areas, the defined landscapes overlap each other to varying degrees.
Rangeland includes 5 million ha of natural grasslands, open forests, and aspen parklands, as well as 250,000 ha of lakes and wetlands, making up 16% of the Intermountain. Lower elevation grasslands and open forests are generally privately owned while higher elevation grasslands and forested rangelands are Crown land. Rangeland wetlands are some of the more productive habitats in the Intermountain, supporting at least 300,000 breeding ducks. While breeding pair densities as high as 7 pairs/ha have been documented on individual wetlands, 2.5 pairs/ha is more typical of average waterfowl habitat. Over 100 years of unmanaged livestock grazing have depleted the vegetation in and around many wetlands, reducing nesting and brood-rearing cover. While range management practices have improved since the 1950s, degraded wetland and upland conditions continue to limit waterfowl productivity.
Forestland makes up 80% of the Intermountain, containing 1,000,000 ha of lakes and wetlands, and supporting approximately 800,000 breeding waterfowl. Although grazing occurs in part of the forestland, timber harvest and management practices affect the majority of the landscape. Impacts include altered water regimes with faster freshets, increased erosion and sedimentation, increased downstream nutrient loading, blowdown along cutblock edges and riparian areas, reduced beaver populations, loss of wildlife trees, and suppression of natural deciduous regrowth following logging. While loss of wildlife trees is obviously detrimental to cavity-nesting waterfowl, other alterations may have a more subtle effect on waterfowl populations and species. There are some private woodlots, but the majority of Forestland is publicly owned Crown land.
The Agriculture/Forest Fringe landscape is defined by the area currently in crop-based agriculture (hay, tame pasture, cereal grains), as well as the adjacent forest fringe into which it will expand in the future. While agriculture occurs in valley bottoms throughout the Intermountain, the projected area of expansion into the forest fringe is primarily focused in the Nechako Valley in the northern part of the region. Approximately 500,000 ha of Crown Forestland are suitable for crop production and approximately 7,500 ha are logged, drained and converted to privately owned agricultural land each year. The Agriculture/Forest Fringe landscape makes up only 4% of the Intermountain, but together with the urban landscape, contains the majority of drained wetlands. A minimum of 20,000 ha of wetlands has been drained to accommodate agriculture. Forty-five thousand ha of wetlands remain in this landscape, supporting approximately 70,000 breeding waterfowl. Given the high productivity of agricultural habitats, this drainage could have resulted in the loss of 140,000 breeding pairs.
The Urban and Urban Fringe landscape is made up of the populated urban areas together with the surrounding habitats into which expanding populations are expected to grow. The current Intermountain population of 900,000 people is expected to increase by 38% in the next 20 years. Towns have a history of draining, filling and building on wetlands as they grow. Present urban area covers 150,000 ha but nearly 9,000,000 ha of Agriculture/Forest Fringe, Rangeland and Forestland falls within 10 km of these areas and is particularly susceptible to impacts from urban expansion, hobby farms, and increased recreational activities. Over 400,000 ha of lakes and wetlands fall within the Urban and Urban Fringe landscape, supporting approximately 400,000 breeding waterfowl.