Terrestrial Invasive Species

Invasive plants are organisms which have been introduced (either accidentally or intentionally) to an ecosystem where they are not native, outcompeting native species for resources and negatively impacting the environment.

Invasive species are the second most common threat for causing species extinction according to the International Union of Conservation and Nature (IUCN). Noxious (and Prohibited Noxious) weeds are regulated invasive plants which must be controlled or destroyed in accordance with the Alberta Weed Control Act.

There are many ways that you can help prevent the spread of invasive plant species and invasive plant pests. 

  1. Know the weeds common to Pigeon Lake 

  2. Remove noxious weeds, persistence is key!

  3. Dispose of weeds at the landfill in a sealed bag (alternatively, some can be dried in the sun) but never compost.

  4. Report noxious weeds to your municipal weed inspector and to EDD Maps Alberta.

  5. Cover bare soil or plant native species. Bare soil invites invasive species to spread and grow.

  6. Play-Clean-Go

  7. Be Plant Wise—Grow Me Instead - Use caution when selecting plants. Ensure non-invasive species are chosen.

  8. Buy it Where You Burn it

Prevent The Spread

Plants

Common Tansy

Tanacetum vulgare

Can reach 1.5 m tall, with narrow toothed leaves and clustered yellow flowers. Control by repeated stem removal by mowing or hand cutting. If seeds are present, immediately bag to prevent chance of spread.

Himalayan Balsam

Impatiens glandulifera

Shallow-rooted and grows to 3 m tall. Leaves are sharply serrated and in whorls of three. Flowers range in colour from rose-purple to pink to white. Control with repeated mowing or “Pick, Break, Drop” - where the weed is picked, broken at the stem, and then dropped to the ground (not forming piles) before it goes to seed.

Control Method - Pick, Break, Drop

PLWA Himalayan Balsam Eradication Project

Scentless Chamomile

Tripleurospermum perforatum syn. T. inodorum

Although its flower isn’t unique, the foliage of the scentless chamomile is easy to distinguish - it looks similar to dill. Plants can grow to 1 m in height and produce up to a million seeds. Mowing can prevent seed production but hand pulling is necessary to stop growth.

Canada Thistle

Cirsium arvense

Despite its name, Canada thistle is an invasive non-native plant. It has spiny leaves and an extensive root system. It can grow as tall as 1.5 m and have purple, pink, or white flowers. The best way to prevent thistle is to maintain a healthy plant cover. Killing the roots is the only effective method for removal, and can take years of persistent mowing and hand pulling to achieve.

Animals

Feral Rabbits

Oryctolagus cuniculus

There are native species (mountain cottontails, snowshoe hares, and white-tailed jackrabbits) but feral rabbits are ones introduced from Europe and Northwestern Africa. Often spreading because of pets being released. Their rapid reproduction can lead to a quick explosion in their population, and they have been reported across Alberta, especially urban areas and grasslands. The size of the population can lead to overgrazing of natural flora and soil erosion

Roof Rat

Rattus rattus

Originally introduced to North America through settler’s ships, this species can carry diseases that can be dangerous to human health. They can also damage crops, properties and carry parasites. They are present throughout British Columbia, and so care must be taken as you drive between provinces. Any sightings should be reported by calling 310-FARM, emailing rats@gov.ab.ca or reporting to the local municiality.

Oxeye Daisy

Chrysanthemum leucanthemum

Grows up to 1 m. Lower leaves are toothed with narrower upper leaves. Flowers are white with yellow centers. Control with removal by hand and digging before it goes to seed while removing the fibrous roots and rhizomes. Take care not to overly disturb the soil. Process will have to continue over years.

Yellow Toadflax

Linaria vulgaris

Varies in size from 15 cm to 1 m, with narrow and numerous leaves that alternate around the stem. Yellow snap-dragon-like flowers are clustered in a spike. Control with removal by hand can work in soft soils as roots can be removed (requires on-going vigilance); mowing can also help.

Orange Hawkweed 

Hieracium aurantiacum

Stems grow between 10-60 cm, are erect and have very few leaves. Both stems and leaves are hairy, a distinguishing feature of non-native hawkweed. Hand pulling is the only effective method for the removal of Orange Hawkweed. The entire root system has to be pulled as root segments can generate new plants.

Tall Buttercup

Ranunculus acris

Norway Rat

Rattus norvegicus

This species is found across the globe, but is not native to North America. Alberta i working to eradicate rats, as they are listed as “pests”, meaning land owners and government have to manage the infestations. They also have rapid reproduction rates, as a female can have up to 15,000 offspring in one year. Alberta has maintained a “rat-free status” since 1937 with no residential populations of Norway or Roof Rats in the province.

Wild Boar

Sus scrofa L.

Native to Europe and Continental Asia, but they can be found on all continents today. In Alberta the species is raised in gourmet meat markets and through some escaping the population has established in the wild, and have adapted to a range of climate and habitats. Any sightings should be reported to local municipal authorities.

Mitigating the impacts of land development involves thoughtful design and management of the built landscape in order to replicate the essential functions of the natural landscape.

- Alberta Clean Runoff Action Guide

References & Photo Credits

Common Tansy photograph by Bjorn S, distributed under CC BY-SA 2.0 license.
Yellow Toadflax by Tony Atkin, distributed under CC BY-SA 2.0 license.
Himalayan Balsam photograph by Loz, distributed under CC BY-SA 2.0 license.
Scentless Chamomile photograph by Rolf Engstreand, distributed under CC BY-SA 3.0 license.
Tall Buttercup by Christian Fischer, distributed under CC BY-SA 3.0 license.
Canada Thistle by Matt Lavin, distributed under CC BY-SA 2.0 license.

Feral Rabbits from https://abinvasives.ca/fact-sheet/feral-rabbits/

Norway Rat, Norway Rat2, from https://abinvasives.ca/fact-sheet/norway-rat/

Roof Rat from wilde braune Ratte, Rattus norvegicus, sitzt auf einer Holzpalette, https://abinvasives.ca/fact-sheet/roof-rat/ 

Wild Boar from https://abinvasives.ca/fact-sheet/wild-boar-at-large/