Invasive Plants

Many hectares of native plant communities in BC have been overtaken by plant species that are referred to as “invasive”.  Invasive species are non-native plants that have been introduced to an area where their natural controlling agents such as insect predators and plant pathogens do not occur and that are undesirable to humans either because they have no obvious beneficial qualities or because they interfere with our land management objectives.

Invasive plants are characterized by their aggressiveness and ability to spread and thrive outside their natural range.  Once established, they may alter native plant communities, out-compete and kill native species or otherwise affect natural ecosystems.  Two species of concern with respect to BC’s rangelands are knapweed.  Both spotted and diffuse knapweed are highly competitive and capable of invading grassland sites to the exclusion of native vegetation.  Knapweed species have been causing major environmental deterioration and reduced forage production in BC’s Southern Interior for more than 50 years.

Photo: Ken MacKenzie (Spotted Knapweed)