Slender collomia (Collomia tenella) COSEWIC assessment and status report: chapter 8
Limiting Factors and Threats
In general, only 2% of BC grassland areas had protected status in 1992 (The Land Conservancy of BC 2002), however grassland and open forest habitats are threatened by a number of factors. Development pressure from the expanding population, habitat fragmentation, degradation due to weed invasion, and off-road vehicle activity have been identified as threats (BC WLAP 2002).
The most imminent threat to the population of Collomia tenella is its vulnerability to extirpation due to the extremely small, occupied area and population size. Such small populations are at risk of inbreeding depression (Primack 1998). Due to lack of genetic variation, these small populations are vulnerable to demographic and environmental variation. Furthermore, suitable habitats for C. tenellain the southern interior of British Columbiaare extremely limited and thus opportunities for colonization are also limited.
Another threat that is likely to have an impact is recreational off-road vehicle use. The authors observed evidence of ATV and dirt bike use in the area of the sites in 2002. The steep and relatively unstable slopes where C. tenella occurs are highly susceptible to disturbance but, at the same time, present a desirable challenge for users of off-road recreational vehicles.
Other potential threats result from activities permitted in the Agriculture Land Reserve. The private property where C. tenella occurs is on the Agricultural Land Reserve (ALR), where primary land use is agriculture. On these lands, development pressures may not appear to be an issue at this time. There have been no applications to have the private property taken out of the ALR for development (Wallace, pers. com., 2003), but the land owners may decide to apply in the future. Housing sales have trended upwards in the last 12-18 months in the Princeton area in tandem with markets in the Okanagan Valley (Fabri, pers. com., 2003).
The ALR status may prevent subdivision development, but does allow other activities that could also potentially threaten the populations. For instance, some types of fill/soil removal are allowable without application to the Agricultural Land Commission (Provincial Agricultural Land Commission 2003). In recent years many tracts of ALR land in southern British Columbia have been converted to housing developments, shopping malls and golf courses, either by decisions of the Agricultural Land Commission or very rarely by an 'order in council' by the sitting provincial legislature.
In addition,in the future, agriculture tourism may be permitted since it is a developing business in the area (Town of Princeton 2003). According to the University of California Small Farm Centre, agriculture tourism operations provide a bridge between urban and rural dwellers (University of California Small Farm Centre 2003). Potential enterprises include festivals, agriculture food and craft shows, guest lodging,off-road motorcycling, ATV recreation, mountain biking, rodeos, tours, and horseback riding. These enterprises could include some intensive land use in the future. Motorcycling, ATV use and horseback riding could all potentially have serious impacts on rare plants if in they occur in areas occupied by plants.
Weed control activities also constitute a potential threat to populations. Under the Weed Control Act, an occupier must control noxious weeds growing or located on land and premises, thus marginally specific chemical weed control substances that kill broad-leaved plant species would likely kill C. tenella. Noxious weeds such as Linaria genistifolia and Bromus tectorum occur in the habitat occupied by C. tenella and could increase as has been witnessed in other southern interior locations. In addition, a variety of other introductions threaten the long-term ecological integrity of the surrounding landscape and may invade the habitat of C. tenella, as they have in other adjacent habitat types. The close proximity of the populations to the highway and powerline right-of-ways also presents a problem in terms of weed control.
Page details
- Date modified: