Why should you care about invasive weeds?

After many hours of pulling invasive weeds it can be hard to stay motivated and see the benefits of your work. Some sites seem to be a losing battle, and it is easy to get discouraged.  

Sometimes you just need a reminder of why controlling invasive plants is important. A visit to a natural area with no invasive weeds can do the trick. It truly is a beautiful sight! There is a huge amount of diversity in plants present. 

Invasive species are the biggest threat to biodiversity, next to habitat loss. They can outcompete our native plants for light, space, water and nutrients. The dominance of a non-native species usually results in a decrease in diversity of native species. This has negative consequences for the habitat of many animal species, especially for insects who require specific plants for food or reproduction; for example, the threatened Behr’s Hairstreak butterfly relies on antelope brush as its larval host plant. 

Behr's Hairstreak butterfly 
Changes in the vegetation present can alter the composition of the organic litter and soil, which can negatively affect detritivores (critters that eat dead organic material). These guys are important components of the food chain and for releasing essential nutrients into the ecosystem.  We have done work at a site where the complete infestation of sulphur cinquefoil has changed the soil so drastically that it no longer looks like a precious grassland! Some invasive plants, such as spotted knapweed, can secrete a toxin into the soil which can inhibit the growth of other plants. 

Some invasive plants can pose a serious threat to wild herbivores and livestock, such as St. John’s-wort, hound’s-tongue, and hoary alyssum. Inedible or toxic invasive plants can outcompete nutritious forage. Plants with burrs or sharp spines may can irritate and injure animals. 

Economically, invasive plants pose a serious threat as well. Once a plant has become widely distributed, it requires a lot of resources to control the spread. There are many economic losses as a consequence of decreased ecosystem function (forestry, agriculture, recreation, etc.) 

If your motivation has returned to tackle those weeds, here are some tips to make sure that your efforts are worthwhile. 
  1. Understand the life cycle of the plant you are dealing with. This will make it easier to decide on a game plan. For example, knowing if a plant is annual, biennial, or perennial can help you focus your efforts and management practices. For example, burdock is a biennial, meaning that the plant will not flower until its second year.
    First year burdock
  2. Know how to manage each species. Each species has different peculiarities that are worth knowing, such as dalmatian toadflax’s ability to multiply from bits of root left in the soil after it has been pulled out. It is more effective to clip the plant below the seed heads to cut down on the amount of seeds in the soil. 
  3. Persistence is key. If you want to eliminate an invasive plant from your property, you will have to get out there every year until the seed bank dries up. 
  4. Prevent invasive plant infestations. Plant in disturbed areas with native or non-invasive exotic plants before invasive plants can establish. Plant native species in natural areas to prevent the spread of invasive plants. 
    Lewis's Mock Orange - a beautiful native flowering shrub

Use this guide to identify invasive plants on your property. For ideas on native and ornamental plants you could plant instead, click here. If you need help or more information, don't hesitate to contact the Okanagan Similkameen Stewardship.