Fish and Wildlife
Native plants provide familiar sources of food and shelter for wildlife. Native fish and wildlife species comprise the vast majority of the animals the Tribes manage habitat for, and they evolved with native plant species. Although some alien plants are sometimes promoted for their value as wildlife food plants, there is little evidence that they are superior to native plants, while there is lots of evidence of problems caused by non-natives. For instance, non-native species like reed canary grass, spotted knapweed, sulfur cinquefoil, Saint John’s wort, and dalmatian toadflax provide much less nutrition for wildlife than native plants and tend to crowd out natives.
If you are a bear and all you see is knapweed, what are you going to eat?Culture
Cultural plants are, by definition, native plants. Important food and medicine plants and plants used for other purposes by the Salish, Kootenai, and Pend d'Oreille once grew in abundance in the Jocko. But their numbers have declined in many places because of invasive non-native species and impacts associated with overgrazing. The maintenance of traditional Tribal culture depends on maintenance of native plant communities.The Problem with Weeds
Invasive alien plants pose a serious threat to biodiversity. Due to a lack of natural controls such as insect pests and competitors, some alien plants easily become established in new areas. Once established, they can out compete and displace the native plant species and form a monoculture (a large area dominated by a single plant). Fish and wildlife suffer.
Disturbances of intact ecosystems that open and fragment habitat, such as land clearing activities and overgrazing, increase the potential for invasion by alien species. Many invasive plants spread quickly and grow so densely that native species cannot re-established themselves. Even without disturbance, native plants can be crowded out by invasive species. Endangered fish and wildlife can be driven from their last habitats by invasive alien plants. Aquatic invasive species can clog waterways, disrupt groundwater flows, degrade water quality. Anyway you look at it, it is best to protect native plants and avoid spreading weeds.