Invasive Plants BC

Invasive Plants

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  Canada thistle (Cirsium arvense) is a root-creeping perennial. Considered noxious under the BC Weed Control Act, this thistle is commonly found on roadsides, cultivated fields, pastures, logged forests, riverbanks, and other disturbed areas. It is a major concern in the Peace River, Omineca and Skeena areas, and is a widespread throughout the province. Canada thistle has purple or white flowers, with stalkless, spiny, dark-green leaves, growing to 0.3-2 metres in height at maturity. Canada thistle spreads rapidly through horizontal roots that give rise to large infestation patches nearby and out-competing native plants. Canada thistle develops seeds sparingly and may produce 1,000 to 1,500 seeds per flowering shoot. Best adapted to rich, heavy loam, clay loam, and sandy loam, it grows poorly in shaded conditions, can tolerate saline, wet, or dry soils, but does not tolerate waterlogged or poorly aerated
  (Tanacetum vulgare) Common tansy (Tanacetum vulgare) is a perennial and considered regionally noxious under the BC Weed Control Act. Common tansy is currently distributed in the following areas: Bulkley-Nechako, Central Kootenay, Columbia-Shuswap, East Kootenay, and North Okanagan Regional Districts, and within Greater Vancouver, Fraser Valley, southeast coast of Vancouver Island, Gulf Islands, Sunshine Coast, and Squamish/Pemberton.Common tansy has yellow disc flowers that resemble buttons in a flat-topped cluster at the top of the plant. With fern-like leaves, common tansy can grow 0.4–1.5 metres in height at maturity.Spread mainly through seeds and roots, common tansy can be transported by birds, animals, and on vehicles that have been in infested areas. Seeds can remain viable for up to 25 years; therefore, stopping seed spread is a main concern. Common tansy prefers sunny areas with well-drained soil, and often infests stream
  (Heracleum mantegazzianum) Giant hogweed (Heracleum mantegazzianum), also known as “Giant Cow Parsnip,” is a perennial and currently distributed in the Lower Mainland, Fraser Valley, Gulf Islands, and central to southern Vancouver Island.Giant hogweed has numerous small white flowers clusters in an umbrella-shaped head, with stout, hollow green stems covered in purple spots. Dark green leaves are coarsely toothed in 3 large segments with stiff underside hairs, and lower leaves can exceed 2.5 metres in length. Giant hogweed can grow up to 5 metres in height at maturity.Giant hogweed is a highly competitive plant due to vigorous early-season growth, tolerance of full shade and seasonal flooding, as well as its ability to co-exist with other aggressive invasive plant species. Each plant can produce up to 100,000 winged seeds (typically 50,000) that remain viable in the soil for up to
  (Ulex europaeus) Gorse (Ulex europaeus) is a spiny, perennial evergreen shrub, considered noxious under the BC Weed Control Act, and thrives on sunny clearings with dry, infertile soil such as sandy or rocky areas, roadsides, fields and pastures, bluffs, cutblocks, and cutbanks. It is currently distributed in Vancouver Island, West Vancouver, some of the Gulf Islands, and Skidegate on the Queen Charlotte Islands. Gorse is a dense evergreen shrub with a single upright stem, spine-like leaves, and fragrant yellow, pea-like flowers. Seedpods are hairy and black. Gorse can grow 1-3 metres in height at maturity.Growing rapidly for the first 15 years, gorse can live up to 45 years. Maturing seedpods explode and disperse up to 18,000 seeds per mature plant. Gorse seeds are easily distributed by ants, animals, birds, and machinery. Since gorse grows mainly by the ocean,
  (Hieracium spp.) Hawkweeds (Hieracium spp.) are perennial plants with 14 non-native species recorded in BC, and are difficult to identify among the 8 native hawkweed species. One of the 14 non-native species, orange hawkweed (Hieracium aurantiacum) is currently the only hawkweed considered regionally noxious under the Weed Control Act. Most hawkweeds have yellow flowers. Invasive hawkweeds are found throughout most forest regions and regional districts in British Columbia. The regional districts east of the Rocky Mountains, Northern Rockies, and Peace River Regional Districts only have a few known invasive hawkweed sites and efforts to prevent further establishment and spread are actively underway. Orange hawkweed is regionally noxious in the East Kootenay, Central Kootenay, Columbia-Shuswap, Thompson-Nicola, Bulkley Nechako, and Cariboo Regional Districts. Hawkweeds have bright orange, orange-red, or yellow ray flowers with several flower heads in clusters at the
Himalayan blackberry (Rubus discolor) is mostly a biennial plant, growing on disturbed sites, along roadsides and rights-of-ways, in pastures, along river and stream banks, fresh-water wetlands, riparian areas, forest edges, and wooded ravines. They are currently distributed on the Lower Mainland, Sunshine Coast, Fraser Valley, Gulf Islands, central to southern Vancouver Island, Queen Charlotte Islands, the Okanagan, and the West Kootenay areas. Himalayan blackberry has petite, white or faint pink flowers with 5 petals, arranged in clusters of 5-20. Flower stalks are prickly, with robust stems (canes) that support large, flattened and hooked or straight prickles. Canes grow up to 3 metres in height and 12 metres in length at maturity. Evergreen leaves are predominantly large, rounded or oblong, and generally grouped in fives on first-year canes and threes on second year, flowering canes. Fruits are up to 2 cm
  (Berteroa incana) Hoary alyssum (Berteroa incana) is an annual to short-lived perennial. Considered regionally noxious under the BC Weed Control Act, hoary alyssum is most common on sandy or gravelly soils and establishes on roadsides, railway embankments, and heavily grazed pastures. It is currently found in south-central and southeastern BC including the Okanagan, Cariboo, Boundary, Thompson, and Kootenay areas.Hoary alyssum has small white flowers with deeply notched petals that are supported on slender stalks. The whole plant is covered in star-shaped hairs that are rough to touch, with grey leaves that clasp closely to the stem. Oval seedpods are chambered and held close to the stem with each chamber containing 5-7 black seeds. Hoary alyssum can grow up to 0.7 metres in height at maturity.Hoary alyssum spreads rapidly through a long season of seed production. Each plant flowers
  (Cynoglossum officinale) Hound’s-tongue (Cynoglossum officinale) is a biennial to short-lived perennial, and is considered noxious under the BC Weed Control Act. Hound’s-tongue is found on dry pasture, roadsides, and logged forestland. Found primarily in the southern interior of BC, it is a major concern in the Kootenay, Okanagan, Thompson, and Cariboo areas.Mature hound’s tongue plants have a woody taproot, with rough, hairy, wide leaves and dull reddish-purple, five-petal flowers. Each flower produces four rounded-triangular seeds covered with hooked prickles. Growing 0.5-1.2 metres tall, stems leaves are short and stalkless. First year plants form a rosette with leaves hanging down to resemble the shape of a dog’s tongue.Each plant produces 2,000-4,000 barbed seeds a year that cling easily clothing, livestock and wildlife, resulting in new infestations spread over great distances. Hound’s-tongue decreases forage production on rangeland and pastures. Barbed
  (Polygonum spp.) Knotweeds (Polygonum spp.) are invasive perennials, with four species found in British Columbia: Japanese knotweed (Fallopia japonica); Bohemian knotweed (Fallopia x bohemica); Giant knotweed (Fallopia sachalenensis); and Himalayan knotweed (Polygonum polystachyum). Knotweeds thrive in roadside ditches, low-lying areas, irrigation canals, and other water drainage systems. They are also found in riparian areas, along stream banks, and in other areas with high soil moisture. Knotweeds occur in the southwest coastal region, the Shuswap, Kitimat, Stikine, Skeena, Columbia, Okanagan, and Kootenay areas, as well as the Queen Charlotte Islands. Additional plants may exist in many gardens in communities across BC.Knotweeds have small white-green flowers that grow in showy, plume-like, branched clusters along the stem and leaf joints. Hollow stems stand upright and are bamboo-like with reddish-brown speckles and thin, papery sheaths. Leaves are heart or triangular-shaped on all

Other Invasive Organisms

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Common Carp. Text.
Didymo (Didymosphenia geminate) or “Rock Snot” is a fresh water diatom most commonly found in high elevation streams and rivers throughout northern Europe and North America. It has long been considered a ‘cold-water’ algae, but has since spread to warmer lower elevation streams and rivers. It can form massive blooms causing significant negative impact to freshwater fish, plants and invertebrates through habitat and food web alteration.   Its most distinguishing feature is a slimy brown layer or ‘ blooms’ that smothers rocks, aquatic plants or any other structures in the water.  The blooms resemble thick slimy looking mats and are distinguished from other forms of algae by its brown, beige or white color.  Didymo is never green in colour.   Although Didymo looks slimy in appearance, it is spongy and scratchy to the touch and has a texture similar to
The Eastern grey squirrel (Sciurus carolinensis) may be cute and fuzzy to on-lookers, especially in the popular tourist areas of Stanley Park in Vancouver, but it is an invasive mammal in British Columbia that is ranked by the Invasive Species Specialist Group (ISSG) as one of the Top 100 Invasive Species in the world. This small mammal has some big ecological impacts—it has depleted populations of the European red squirrel through out-competition and disease (parapoxvirus), and displaces native birds of their nesting habitat, eating the birds’ eggs and nestlings. It also competes with native mice and voles. Economically, Eastern grey squirrels cost homeowners repairs due to digging up of lawns and gardens, chewing through electrical wires, eaves and shingles, and nesting in roofs, attics, and chimneys. Fruit and nut trees and vines may not produce as well due to the
Largemouth Bass  
The New Zealand mud snail is a very tiny aquatic snail (often smaller than your baby fingernail) and is native to fresh waterbodies in New Zealand. The New Zealand mudsnail is typically light to dark brown in colour but may look black when wet. The shell of adult mud snails usually have 5 – 6 whorls that lean to the right, are less than 5 mm in size and can easily be confused with other fresh water and native snails. It is thought that the New Zealand mudsnail was transported to North America in the ballast water of transport ships originating from Europe and Asia. It was first recorded in North America in the late 1980’s in Idaho’s Snake River and is now widespread in many states including Washington, Oregon, and California. The New Zealand mudsnail can live in a
Appropriately named for its ‘fire’ like sting, the European fire ant (Myrmica rubra) will attack aggressively if disrupted. When this ant attacks, it pinches down with its mandible then swings around and stings multiple times. In a few cases it has produced severe allergic reactions including anaphylactic shock. The European fire ant is a small red to brownish red ant that can be identified by its two waist segments, our native ant only has one, and the two backward pointing spines and stinger (visible with a magnifying glass).  This invasive insect was introduced from its native Eurasia to eastern North America. It was first sighted along the eastern seaboard of the United States in the early 1900s and has since spread across several Canadian provinces including Nova Scotia, New Brunswick, Quebec, Ontario, and into British Columbia. European fire ant nests

Feature Article: Economic Impacts

Economic Impacts of Invasive Plants in BC

The sudden ignition of a brightly lit wildfire on the horizon sparks immediate actions and budgeted resources. After all, the loud, crackling, hot flames are hard to ignore as they advance toward communities. So how should we respond to the silent, but significant, threat of invasive plants that appear pretty and harmless along the highways and farmer’s fields, in public parks and backyard gardens of British Columbia?

Despite their attractive appearance, invasive plants are one of the five most significant causes of biodiversity loss and change to ecosystem functions, as reported by the Millennium Ecosystem Assessment. They carry potential negative impacts to the economy, environment, and society; therefore, preventative planning and careful budgeting are required.

To date there is no established annual budget in BC to control invasive plants. Once established, the environmental impacts of invasive plants can be as significant as those caused by wildfire, and are often irreversible.

Recent studies on the economic impacts of invasive plants in BC have staggering results. A 2006 survey showed that approximately $7 million was spent on invasive plant management activities in BC that year (IPCBC Economic Impacts Baseline Report #6). Results of the 2009 Economic Impacts of Invasive Plants in BC (Report #12) analysis indicate that without intervention, the economic damage caused by each invasive plant in the study was estimated to range from $1 to 20 million dollars in 2008, increasing to between $5 and 60 million by 2020 (based on 2006 Canadian dollars). The total expected damages, in the absence of any management, were estimated to be a minimum of $65 million in 2008, rising to $139 million by 2020. These values are likely underestimates as economic data were not available for all potential impacts.

The above projections indicate enormous economic losses and severe environmental damage in the decade ahead, which may be worsened by climate change. Thus, a consistent province-wide invasive plant management budget is needed. Current funding is a result of improved awareness about invasive plants in BC and partnerships between the provincial government, key stakeholders, and the Invasive Plant Council of BC. Some of these funds have been dedicated to undertaking comprehensive economic impacts research.

To date, the majority of research reports assessing the economic impacts of invasive plants in BC have focused on the agriculture sector. Crop losses alone cost BC farmers and ranchers over $50 million annually due to invasive plant species, like knapweed, that infest rangelands and reduce forage quality, states the BC Ministry of Agriculture and Lands. Several million dollars more are spent annually to control invasive plants through herbicide and cultivation.

In addition to impacts on agricultural and range resources, invasive plants can impact forestry operations by competing with seedlings for light, nutrients, and water; and recreation opportunities by puncturing tires, obstructing trails, and reducing aesthetics. These environmental impacts lead to costly restoration of recreational trails, re-planting of tree seedlings, as well as reduction in value of personal and commercial property.

The impacts of invasive plants to all natural resource sectors of the economy are being felt across the nation. The Canadian Food Inspection Agency (CFIA) estimates that of the 485 invasive plant species in Canada, invasive plants in crops and pastures alone cost approximately $2.2 billion every year. The CFIA classifies 94 invasive species as agricultural or forest pests and estimates that these regulated species cost the Canadian economy $7.5 billion annually.

In the Prairie provinces, canola yield losses and treatment for Canada thistle (Cirsium arvense) cost an estimated $320 million per year (CFIA). In Manitoba, leafy spurge (Euphorbia esula) infests 340,000 acres of land, costing an estimated $19 million per year in protection of grazing land, public land, and right-of-ways.

Furthermore, a United States study reports that the invasion of leafy spurge in four northern states has resulted in annual losses of US $129 million, equivalent to approximately 1,433 jobs. According to the CFIA, the total cost of preventative measures, control programs, and lost production due to invasive species is estimated to exceed $137 billion a year in the US.

Invasive plants have no boundaries, and their introduction to an environment may threaten the survival of native species, and can also prompt trading partners to impose restrictions, causing further economic losses.

A US study conducted by the Center for Aquatic Conservation at the University of Notre Dame and University of Wyoming suggests invasive species transferred in ship ballasts may be costing the Great Lakes region more than $200 million a year in losses to commercial fishing, sport fishing, and the area's water supply.

On a larger scale, invasive species reduce the effectiveness of development investments by choking irrigation canals, fouling industrial pipelines, and impeding hydroelectric facilities. Invasive species therefore contribute to social instability and economic hardship, placing constraints on sustainable development, economic growth, poverty alleviation and food security, says the Global Invasive Species Programme (GISP).

The Secretariat of the Convention on Biological Diversity concurs, saying that invasive species can exacerbate poverty and threaten sustainable development through their impact on agriculture, forestry, fisheries, human health, and biodiversity, which is often a basis of livelihoods of people in developing countries. The alien aquatic plant, water hyacinth (Elchhornia crassipes), for instance, costs an estimated US $100 million a year on issues related to water use in developing countries.

Despite the growing evidence of the economic impacts caused by invasive species, the level of awareness amongst decision-makers is still relatively low, says the GISP. The economic impact of many invasive species is poorly documented because of the difficulty in assessing impacts to habitats, such as forests, rangelands, aquatic, wetland, and riparian sites. A conservative estimate by the GISP puts the global cost of tackling invasive species at $1.4 trillion each year, 5% of the global economy.

Ironically, most introductions of invasive species are based on economic motivations, but are seldom preceded by cost-benefit analysis that discusses societal and ecological consequences, states the BC Ministry of Environment. It is rarely those responsible for introducing an invasive species, either intentionally or accidentally, who pay for resulting damages. Instead, consumers, other resource users, and tax-payers bear most of the burden.

Without greater intervention and an appropriate budget, the cost of controlling invasive plants will increase exponentially over time. These “invaders” have the capacity to permanently alter ecosystems, reduce property values, impact natural resource sectors of the economy, and in the worst cases, cause the extinction of native species. They are silently and rapidly impacting the landscape with the same swiftness and destruction as a wildfire, but without the bells and whistles to sound the alarm.

Article (Microsoft Word - 40 kb)


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