Vaseux–Bighorn National Wildlife Area Management Plan: chapter 2

2. Ecological resources

2.1 Terrestrial and aquatic habitats

The wetlands of the valley bottom are embedded in a matrix of riparian woodland and shrub grassland. The grassland of the lower elevations gives way to open forests of Douglas Fir and Ponderosa Pine in rocky areas, on steep slopes, and on cliffs at higher elevations. The lake and associated marshes are important breeding and stopover sites for waterfowl and many other species of migratory birds. The unusual and rare habitats that make this area special include shrub grassland parkland (mainly open grass with sparse shrubs and trees scattered throughout) containing old growth Ponderosa Pine, wide unfragmented riparian birch thickets, undisturbed cliffs including talus and rock outcroppings, and shallow wetlands. These special habitats support a number of rare species, with the transitional zones between them being biodiversity hotspots (Chapman et al. 1997b).

Grasslands of the National Wildlife Areas (NWA) are characterized by Bluebunch Wheatgrass and Needle-and-Thread Grass (Grasslands Conservation Council of British Columbia (B.C.) 2003). Antelope Brush, Sagebrush and rabbitbrush dominate shrub habitats. These habitat types are relatively rare and sensitive to disturbance, and the grasslands are threatened by the ongoing invasion of exotic and alien plant species.

At higher elevations, grasslands grade into parklands with denser tree cover, where pine gives way to Douglas Fir with an understorey of Slender Fescue, Oregon Grape, Sumac and Poison Ivy. Rock Rose (bitterroot), Arrow-Leaved Balsamroot, Sagebrush and Mariposa Lily are among the floral highlights of the higher-elevation forested parklands (Dawe et al. 2004). Widely-spaced stands of Ponderosa Pine with a minor component of Douglas Fir (Nicholson et al. 1991) are found in some areas. Bluebunch Wheatgrass and fescues dominate the herb layer and, on drier sites, Antelope Brush and rabbitbrush commonly occur. In wetter areas, Trembling Aspen, Saskatoon Bush, Water Birch and a variety of willow species predominate. The vegetation that defines the northern wetlands and lake shoreline riparian areas is typically dominated by sedges and cattails. Other common marsh plants are Bulrush, Common Silverweed and Yellow Pond Lily. At the edges of watercourses, Slender Willow, Water Birch, Red Osier Dogwood and Mountain Alder are present (Bryan et al. 1997).

2.2 Wildlife

The National Wildlife Areas (NWA) provides seasonal and year-round habitat for many small and large wildlife species, such as songbirds, raptors, ungulates, waterfowl, bats, carnivores, fur-bearers, amphibians, reptiles and a large diversity of plants and invertebrates. A time-limited and partial inventory conducted within the NWA identified 30 invertebrate species, 5 fish species, 2 amphibian species, 8 reptile species, 132 bird species, and 17 mammal species between May and August 2003 (Dawe et al. 2004).

2.3 Species at risk

Thirty species included on Schedule 1 of Species at Risk Act (SARA) are currently known to occur in the NWA. An additional 19 species tracked by the British Columbia (B.C.) Conservation Data Centre as either red- or blue-listed, as well as three red-listed communities and one blue-listed plant community, also occur within the NWA’s boundaries (B.C. Conservation Data Centre 2010) (Table 3).

2.4 Vision

Vaseux-Bighorn NWA was established for conservation purposes. The long-term vision for the NWA is to maintain and enhance habitat for all native wildlife, with priority being given to species at risk and their associated habitats.

2.5 Goals and objectives

Vaseux-Bighorn NWA was originally selected as a protected area to protect habitat for a remnant population of California Bighorn Sheep and to protect a collection of rare and unique habitats. Conservation priorities have shifted over time, but the maintenance of habitat for rare and unique species continues to be the first priority, including the maintenance of habitat for Bighorn Sheep. The NWA is classified under the International Union for Conservation of Nature criteria for protected areas as a Category IV protected area, which indicates that the NWA is to be managed “mainly for conservation of habitat and species through management intervention.^Footnote[14]

The goals and objectives seek to create conditions that mimic those that would occur under natural ecological processes. These are goals to which Environment Canada aspires and, if achieved, would produce tangible benefits for habitat and wildlife, particularly migratory birds and species at risk, over the long term. To achieve the overall conservation goal, the ecological goals and objectives for Vaseux-Bighorn NWA are as follows:

Goal 1: Restoration and management of important habitats and ecosystems, particularly for species at risk, migratory birds and other priority species

• 1.1. Sub-Goal: Forest habitats will be maintained to mimic an ecosystem driven by periodic low-intensity fires so that populations of species at risk, migratory birds and other priority species are sustained and/or residences and habitats are created, restored or maintained through active management.
  1. Objective: 50% of conifer forest will contain less than 25% canopy closure over the long term (by 2025).
  2. Objective: 50% of conifer forest will have less than 5% downed woody material over the long term (by 2025).
• 1.2 Sub-Goal: Riparian habitats will be maintained so that populations of species at risk, migratory birds and other priority species are sustained and/or residences and habitats are created, restored or maintained through active management.
  1. Objective: Riparian areas and cottonwood forests do not decrease in extent.
  2. Objective: The spatial extent of riparian woodlands in the Northwest Marsh Unit will be increased from 4 to 16 ha in the medium term (by 2020).
• 1.3 Sub-Goal: Wetland and meadow habitats will be maintained so that populations of species at risk, migratory birds and other priority species are sustained and/or residences and habitats are created, restored or maintained through active management.
  1. Objective: Half of historic side channels will contain permanent water over the long term (by 2025).
  2. Objective: Restored riparian and wetland pond habitat will be increased to 16 ha by 2020.
  3. Objective: Cattail wetlands will be managed so that closure does not exceed 50% and is patchy when assessed in a grid of 25 x 25 metres (m) by 2020.
• 1.4 Sub-Goal: Rocky cliffs and talus slope habitats will be maintained so that populations of species at risk, migratory birds and other priority species are sustained and/or residences and habitats are created, restored or maintained through active management.
  1. Objective: Stop illegal access that damages these habitats.
• 1.5 Sub-Goal: Grassland and Antelope Brush habitats will be maintained so that populations of species at risk, migratory birds and other priority species are sustained and/or residences and habitats are created, restored or maintained through active management.
  1. Objective: Antelope Brush habitat does not decrease in spatial extent.
  2. Objective: The spatial extent of Antelope Brush habitat is within 20% of its historical maximum by 2025.

Goal 2: Control of invasive species

• 2.1. Sub-Goal: Habitat and vegetation will be actively managed to eliminate (where possible) or reduce the extent and density of alien and exotic species of plants.
  1. Objective: The size and number of habitat patches known to be dominated by alien and invasive species (more than 25% of cover) will have decreased over time.

Goal 3: Control of unauthorized activities in the NWA

• 3.1. Sub-Goal: Eliminate off-trail recreational activities in the NWA.
  1. Objective: On an ongoing basis, the number and nature of incidents where evidence of illegal activities occur in Vaseux-Bighorn NWA is documented and reported to Environment Canada’s Wildlife Enforcement Division.

Goal 4: Reduce risk of catastrophic fire in the NWA

• 4.1. Achieve sub-goal 1.1 so that fuel load is reduced through the removal of young trees and downed woody material.
  1. Objective: 50% of conifer forest will contain less than 25% canopy closure over the long term (by 2025).
  2. Objective: 50% of conifer forest will have less than 5% downed woody material over the long term (by 2025).

Goal 5: Limit anthropogenic impacts on water quality in the NWA

• 5.1. Sub-Goal: The quality of surface water in Vaseux-Bighorn NWA will be sustained or improved to a level necessary to meet native aquatic species’ life history requirements.
  1. Objective: Detectable concentration levels of pesticides, herbicides and other toxic chemicals in surface water must meet Canadian Council of Ministers of the Environment (CCME) guidelines.
  2. Objective: Sources of water contamination are identified and a compliance promotion plan is produced (by 2025) to reduce the prevalence of these sources over the long term.

2.6 Evaluation

Annual monitoring will be performed within the limits imposed by financial and human resources. The management plan will be reviewed in five years and every ten years thereafter. Evaluation will take the form of an annual review of monitoring data obtained from the monitoring and research projects outlined in sections 4.5 and 4.6. These data and the annual review will be used to inform future management and to evaluate federal contributions to the recovery of the numerous species at risk in the region.