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To develop a working multi-jurisdictional weed management strategy and encourage participation from all agencies located within the management area.



The Thompson Nicola Region Invasive Plant Strategic Plan is designed to develop inter-agency coordination of invasive plant management within the Thompson Nicola Regional District. Invasive plant management on Crown land falls within the jurisdiction of the Ministry of Forests, Ministry of Transportation and Ministry of Environment. The strategic plan will also attempt to coordinate the priorities and management goals of all of the various stakeholders, agencies and private landowners who have invasive plant requirements under the Provincial Weed Act. The plan hopes to encourage the continued, coordinated efforts towards effective management of invasive plant species throughout the Thompson Nicola region.


Invasive plants found within the Thompson Nicola region have categorized according to their aggressiveness in terms of introduction and establishment, as defined below:

  • Category 1: invasive plants invade even undisturbed habitats and dominate them. Domination implies the invasive plant becomes the most abundant species across the entire site or area of the plant community being invaded. The invasion can progress slowly or rapidly. Potentially aggressive species not yet known to exist or those which exist in limited quantities within the boundaries of the Thompson-Nicola Regional District will be treated within Category 1 in order to promote eradication of these species where feasible.
  • Category 2: invasive plants invade even undisturbed habitats. They become very prevalent and may form dense patches but usually do not dominate the entire site or area of the plant community. If category 2 invasive plants invade the entire site or plant community they tend not to dominate the site.
  • Category 3: invasive plants can invade undisturbed habitats but they usually require some disturbance to gain entry. Once in a habitat they usually do not dominate the site unless management problems are occurring.
  • Category 4: invasive plants can invade even undisturbed habitats but they do so at a slow pace and rarely dominate the site. Category 4 invasive plants may go through large population fluctuations. This may be the result of the fluctuation in biocontrol agent populations or cyclic patterns the plant displays.


Containment lines are used to define management areas within large infestations. The goal is to treat all sites found outside defined containment lines with the goal of preventing spread of the plant. Within the containment line a management area is created for the plant species. Treatment within these management areas will be based on individual agency/landowner priorities. Should an agency have management plans within the management area an attempt to coordinate surrounding agencies to support the management plans will be made. Containment lines have been created for Spotted Knapweed, Sulphur Cinquefoil, Plumeless Thistle, Hoary Alyssum and Blueweed.


All inventoried sites will be ranked into one of four priority levels. Ranking is based on the plant species category, infestation size and location, and containment lines.

Site Priority 1 – Extremely High Opportunity for Control

Purpose or Intent: To stop the spread of highly invasive weeds threatening currently uninfested, highly susceptible areas.

  • Areas outside defined management areas (containment lines)
  • Species defined as 'New Invaders'
  • Areas defined as Priority 1 by land agencies/managers.

Site Priority 2 – High Opportunity for Control

Purpose or Intent: To stop the spread of weeds threatening currently uninfested, highly susceptible areas. These sites have a good expectation of control. This priority also includes sites that are threatening a large neighbouring economics base, for example, the seed crop of the Peace River.

  • Satellite plants: Eradicate single plants and isolated patches prior to seed production.
  • Seed dispersal sites: Roadsides, parking lots, trails, ditches and streams and other places where weeds can become established and be dispersed by human or natural vectors.
  • Small infestations: Small infestations can often be managed before they become larger and more costly to control. "Small" typically refers to weed infestations under 0.25 ha.
  • Other high impact sites: For example, road pullouts, recreation areas, campgrounds and other high-use areas.

Site Priority 3 – Moderate Opportunity for Control

Purpose or Intent: To stop the enlargement of sites of greater than or equal to 0.25 ha and less than or equal to 0.5 ha. Also, to prevent the growth of sites containing plants which are well established within the region but for which effective biological control agents have been released and are controlling the abundance, vigour, and distribution of the invasive plants.

Site Priority 4 – Low Opportunity for Control

Purpose or Intent: To stop the growth and contain sites that have species which are common and widespread throughout all or most of the available habitat within the region. This includes sites larger than 0.5 ha in moderately susceptible areas.


Profiles of thirty five invasive plants within the Thompson-Nicola Region have been created to provide information on plant identification features, ecology, habitats and distribution and management options. Click here to download these Plant Profiles.


The Thompson Nicola Region has been divided up into a total of ten management units which correspond to the TNRD Electoral boundaries (as shown on the map below). The Strategic Plan is currently being practiced in Units I and N, under the Single Agency's 2008 Pilot Project. SIWMC is currently evaluating the successes and challenges of the collaborative invasive plant management programs in these areas and based on the results, will be looking into the possibility of expanding the Project to include additional Management units



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