Introduced Species

Agronomic Grasses (Various species)

Factsheets

• Garry Oak Ecosystems Recovery Team

Description

A variety of introduced annual and perennial grasses have become established on Galiano Island. These include:

• Agrostis capillaris – colonial bentgrass
• Agrostis stolonifera – creeping bentgrass
• Aira caryophyllea – silver hairgrass
• Aira praecox – early hairgrass
• Anthoxanthum aristatum – small sweet vernalgrass
• Anthoxanthum odoratum – sweet vernalgrass
• Alopecurus spp. – foxtails
• Bromus diandrus syn. rigidus – rigid brome
• Bromus hordeaceus – soft brome
• Bromus sterilis – barren brome
• Bromus tectorum – cheatgrass
• Cynosurus echinatus – hedgehog dogtail
• Cynosurus cristatus – crested dogtail
• Dactylis glomerata – orchard grass
• Echinochloa crus-galli – barnyardgrass
• Elymus repens – quackgrass
• Festuca trachyphylla – hard fescue
• Holcus lanatus – velvet grass
• Hordeum murinum – wall barley
• Lolium perenne – perennial ryegrass
• Phalaris arundinacea – reed canarygrass
• Phleum pratense – Timothy grass
• Poa annua – annual bluegrass
• Poa bulbosa – bulbous bluegrass
• Poa compressa – Canada bluegrass
• Poa pratensis – Kentucky bluegrass
• Schedonorus  arundinaceum – tall ryegrass
• Schedonorus pratense – meadow ryegrass
• Vulpia bromoides – barren fescue
• Vulpia myuros – rattail fescue

Habitat

Agronomic grasses become established in exposed, disturbed soil.  They are common in old pastures and agricultural areas, and are quickly become the dominant cover on recently disturbed sites.

Impact

Agronomic grasses on Galiano Island form a dense thatch that smothers low-growing native species and prevents the regeneration of native ecosystems.  They are especially damaging in Garry Oak ecosystems, where they often completely replace native species.

Management

Management will differ by species (see links to individual guides, above).  Some species can be easily removed by hand; others will have dense root systems that will require smothering.  Some species may be impossible to eliminate from a site until dense forest cover is established.  On permanently open sites such as woodlands and Garry Oak meadows, careful management is necessary to favour native species over agronomic grasses.

Our Experience

Agronomic grasses are now widespread in virtually every ecosystem on Galiano Island, and are effectively here to stay.  On cleared sites, they should be managed until a native tree canopy can be established to shade them out; on sensitive sites such as Garry Oak ecosystems and coastal bluffs, they should be managed to mitigate their impacts on native species.

Carpet Burweed (Soliva sessilis)

Factsheet

• Garry Oak Ecosystems Recovery Team

Description

Low growing winter annual with finely divided leaves and small white flowers.

Habitat

This South American annual has moved into Garry Oak ecosystems, where it forms a dense carpet.  On Galiano Island, it is rare but occasionally encountered at select sites in woodlands and open ecosystems.  It typically grows in areas that are wet in the winter, and dry and disturbed in the summer, such as pathways.

Impact

Shares a similar pattern of growth with many native annuals of Garry Oak systems, effectively replacing them where it grows in dense populations.

Management

Management activities must take place in the winter, prior to flowering and seed set.  Small populations can be carefully hand-pulled, bagged, and disposed of in the landfill or by burning.  Larger populations can be treated with a propane torch in the wet season.

Our Experience

This plant is established in a few locations but is not yet a major problem on Galiano.  Island residents should keep an eye out for it, and notify the landowner and the Invasive Species Council of BC if they encounter it.

English Hawthorn (Crataegus monogyna)

Factsheet

• Garry Oak Ecosystems Recovery Team

Description

Small, thorny deciduous tree growing up to 10 m tall.  Leaves are distinctly lobed; clusters of showy white flowers are followed by round red berries.

Habitat

This European tree readily establishes in sunny, cleared areas that have been disturbed by agriculture or grazing.  It also moves into native wetlands.  On Galiano Island, it is frequently found in old fields and drained wetlands.

Impact

English hawthorn can form a dense shrubby layer on disturbed sites and in wetlands, preventing the regeneration of native trees and shrubs.

Management

Wear thick gloves and clothing to limit scratches from thorns.  Small diameter saplings can be pulled by hand or using a weed wrench.  Tree-sized plants should be cut above ground, and then the roots must be excavated.  Roots that are left intact may re-sprout.  Removed plant material with fruits should be piled and burned; plant material without fruits can be dried out on an impermeable membrane, then discarded in the forest in a shady area, provided it is located where it will not result in a fire hazard.

Our Experience

English hawthorn produces many seeds, and disperses widely through birds.  Cut stems may re-sprout, so it is important to remove the roots completely or cut repeatedly.

English Holly (Ilex aquifolium)

Factsheet

• Invasive Species Council of Metro Vancouver

Description

Evergreen tree with waxy, sharply-toothed leaves growing up to 5 m tall.  Inconspicuous flowers are followed by clusters of round red berries.

Habitat

This European tree tolerates both sun and shade and has established in a variety of ecosystems.  On Galiano Island, can occur as a forest understory tree or as a tall shrub in open ecosystems such as meadows, wetlands, and old fields.

Impact

This prickly plant can disperse itself widely through fruit that is palatable for birds, and grows in a broad range of ecosystems.  It displaces native species and creates unpleasant, impenetrable hedges that limit human and wildlife movement.

Management

Wear thick gloves and clothing to limit scratches from prickly leaves.  Small diameter saplings can be pulled by hand or using a weed wrench.  Tree-sized plants should be cut above ground, and then the roots must be excavated.  Roots that are left intact will re-sprout with multiple trunks.  Removed plant material with fruits should be piled and burned; plant material without fruits can be dried out on an impermeable membrane, then discarded in the forest in a shady area, provided it is located where it will not result in a fire hazard.

Our Experience

English holly produces many seeds, and disperses widely through birds.  Cut stems will re-sprout, so it is important to remove the roots completely.

English Ivy (Hedera helix)

Factsheets

• Invasive Species Council of BC
• Invasive Species Council of Metro Vancouver
• Garry Oak Ecosystems Recovery Team

Description

Evergreen perennial vine that can climb up to 30 m into the canopy.  Leaves are dark green, lobed, and waxy; stems grasp onto tree trunks through aerial roots.  Inconspicuous flowers are followed by purplish clustered fruits.

Habitat

This Eurasian species has been widely planted as an ornamental.  It grows in both sun and shade, and can form a thick carpet on the forest floor.  It will climb and blanket trees, making them more vulnerable to blowdown and disease.  On Galiano Island, it is occasionally found in forested areas near settlements.

Impact

English ivy excludes native vegetation by smothering it and taking up all the available light.  It reduces wildlife habitat and forage, and is a vector for bacterial leaf scorch (Xylella fastidiosa), which affects native oaks and maples.

Management

Wear gloves and a long-sleeved shirt to avoid skin rashes.  Cut vines that have established on trees near the ground level, firmly severing the connection.  Remove rooted plants by hand, digging carefully to remove the rhizomes.  Several passes will be required to remove remnant root fragments.  On sites where native species are not present, the area can be covered with an impermeable membrane post-removal for 3-6 months to reduce the need for future removal efforts.  Removed plant material should be burned.

Our Experience

English ivy is very difficult to remove once established.  Large populations can be managed to prevent spreading by creating and enforcing a perimeter.  Any vine that begins to climb a tree should be cut to prevent aerial fruit production.  English ivy should be removed wherever small populations occur, and spread should be managed in larger populations if removal is not feasible.

Himalayan Blackberry (Rubus armeniacus syn. Rubus discolor)

Cutleaf Blackberry (Rubus laciniatus)

Factsheets

• Invasive Species Council of BC
• Invasive Species Council of Metro Vancouver
• Garry Oak Ecosystems Recovery Team

Description

Evergreen perennial shrubs from robust thickened canes with large prickles that grow up to 3 m tall and 12 m long.  White, five-petalled flowers are followed by red and eventually black cluster fruits.  Leaves of both species have five large leaflets. In Himalayan blackberry, leaflets are roughly toothed and green above, reflective silver below.  In cutleaf blackberry, leaflets are deeply incised.

Habitat

Eurasian species that prefer rich soils.  On Galiano Island, they are found on forest edges, in old fields, and in rich riparian areas.

Impact

These aggressive shrubs form large, dense, impenetrable thickets that clog waterways, smother native species, and prevent wildlife movement.

Management

Wear thick gloves and clothing to prevent injury from prickles.  Cut stems prior to flowering, then dig out enlarged rhizomes by hand, ensuring that the majority of root chunks are removed.  Several passes are usually required to remove remnant root chunks.  Removed plant material can be dried in the sun on an impermeable membrane, and then either burned or discarded in the forest in a shady area, provided it is located where it will not result in a fire hazard.

Regular mowing or grazing will also eventually deplete root reserves.

Our Experience

Introduced blackberries are both a nuisance and – for at least one month a year – a treat.  They can, however, quickly create large thickets on rich sites that would otherwise support productive native plant communities.  This is especially a concern in soils that have been enriched through agricultural land use.  Remove Himalayan and cutleaf blackberry wherever they occur in proximity to native streams and riparian areas.

Gorse (Ulex europaeus)

Factsheets

• Invasive Species Council of BC
• Garry Oak Ecosystems Recovery Team
• Capital Regional District

Description

Spiny, heavily armoured perennial shrub growing up to 3 m tall.  Yellow pea-like flowers resemble those of Scotch broom (Cytisus scoparius), followed by black hairy seedpods that split when dry.

Habitat

This Mediterranean shrub has moved onto poor, exposed soils on disturbed sites.  On Galiano Island, it occurs in several locations, usually on or near rocky coastal bluffs.

Impact

This aggressive plant displaces native species in sensitive coastal ecosystems, and can be a hazard for both wildlife and human beings.  It increases fire hazard and erosion where it occurs, and fixes atmospheric nitrogen into the soil, where it favours non-native species.

Management

Wear thick gloves and clothing to prevent injury.  Cut plants during or prior to flowering as close to the root crown as possible; roots should then be carefully excavated and removed.  Repeated cutting will be necessary to exhaust root resources if roots are not removed.  Small plants should be pulled out (gingerly).  Cut plant material with flowers or seeds should be burnt; plant materials without flowers or seeds can be discarded in the forest in a shady area, provided it is located where it will not result in a fire hazard.

Our Experience

Gorse is a major nuisance and requires care to remove safely.  It should be removed wherever it occurs.

Knotweeds (Reynoutria syn. Fallopia spp.)

Knotweeds (Polygonum polystachyum syn. Koenigia polystachya)

Factsheets

• Invasive Species Council of BC
• Invasive Species Council of Metro Vancouver
• Capital Regional District

Description

Robust herbaceous perennials with hollow stems growing up to 1-5 m tall in dense thickets.  Small white inflorescences branch out from leaf axils in showy plumes.

Habitat

This collection of Asian ornamentals form monocultural colonies in sunny areas.  On Galiano Island, they are uncommon on disturbed sites in rich soils.

Impact

Knotweed is capable of growing through concrete and asphalt, and forms dense monocultures that completely exclude native species.  It causes erosion in riparian areas.

Management

Do not plant or transport knotweed.  Once a population is established, herbicide is necessary to remove it. Digging and mowing should only be performed if (a) the population is small enough to allow for complete removal, and (b) all material is bagged and disposed of appropriately in a landfill.

Our Experience

Prevention is the best approach to limit the spread of knotweeds.  Established populations should be removed by professionals wherever they occur.

Common Periwinkle (Vinca minor)

Bigleaf Periwinkle (Vinca major)

Factsheet

• Invasive Species Council of BC

Description

Evergreen perennial groundcover with waxy green leaves and purple, five-petalled flowers.

Habitat

This Eurasian ornamental has been widely planted in home gardens, where it escapes into native forests and woodlands.  It is highly shade-tolerant.  On Galiano Island, it forms a dense groundcover that spreads outward from old homesteads and gardens.

Impact

Periwinkle blankets the forest floor and smothers native species.

Management

Small populations can be removed by carefully digging up roots; several passes will be required to removal all root fragments.  Large populations can be mowed and then smothered with an impermeable membrane for 6 months or more, until plants are dead.  Several repeated rounds of smothering and exposure may be required.  Removed plant material should be bagged and disposed of at landfill, or smothered until completely dead and left in place.

Our Experience

Periwinkle is incredibly difficult to remove once a population is established, and we are still experimenting to see what works best.  Small populations should be removed immediately wherever they occur.  Attempting to remove large populations by hand will result in significant soil disturbance; in these circumstances, it may be best to establish a perimeter and prevent population expansion.

Poison Hemlock (Conium maculatum)

Factsheets

• Invasive Species Council of Metro Vancouver
• Capital Regional District

Description

Robust herbaceous biennial with finely dissected leaves and hollow stem with purple spots, growing up to 3 m tall.  Large, showy white umbels inflorescences are reminiscent of carrot flowers.

Habitat

This European species establishes on wet sites with rich, disturbed soils.  On Galiano Island, it is uncommon in disturbed seepage areas and riparian zones.

Impact

Poison hemlock is deadly poisonous and should never be ingested.  It can outcompete native riparian vegetation.

Management

Protective gear, including rubber gloves, a face shield, and thick clothing should be worn when removing poison hemlock.  Young plants can be pulled; ensure that the entire taproot has been removed.  Larger plants can be cut off at the base, repeatedly if necessary.  Flowers can be cut and bagged.  All plants parts should be bagged and disposed of in a landfill.

Our Experience

This species is still uncommon on Galiano and should be removed wherever it occurs by a professional.

Reed Canarygrass (Phalaris arundinacea)

Factsheet

• Invasive Species Council of Metro Vancouver

Description

Robust perennial grass growing up to 2 m tall, forming large colonies.   Large white flowers are narrow and closed early in the season before opening up into busy panicles.

Habitat

This aggressive hybrid species grows in ditches, wetlands, old fields, and floodplains.

Impact

Reed canarygrass displaces native wetland vegetation, providing little food for wildlife.  It can alter wetland hydrology and clog creek and wetlands.

Management

Small populations can be dug out by the roots and burned.  Larger populations can be repeatedly mowed and smothered with an impermeable membrane for 3-6 months.  Several rounds of smothering and exposure may be necessary.  On open sites where tree regeneration is desirable, the establishment of tree cover will eventually shade out reed canarygrass.  Removed plant material can be burned, or dried out on an impermeable membrane before being discarded in the forest in a shady area.

Our Experience

This is a very challenging species to remove, and we are still experimenting with control techniques.  In the long term, re-establishing a native tree canopy will help ensure populations don’t return.  In permanently open sites, a combination of mowing and smothering may be effective over time.  Reed canarygrass should be removed wherever it occurs in small populations, and managed in circumstances where large populations have established.

Scotch Broom (Cytisus scoparius)

Factsheets

• Invasive Species Council of BC
• Invasive Species Council of Metro Vancouver
• Garry Oak Ecosystems Recovery Team

Description

Bushy, green, woody shrub with a  woody brown main stem and green branching stems. Flowers are yellow and pea-like, followed by dark pea-shaped fruits that split when dry. Green stems can photosynthesize year-round. Can grow up to 3 meters tall.

Habitat

Scotch broom originates from the European Mediterranean, and thrives in full sun on mineral soils.  On Galiano Island, it is common in power-line right-of-ways, roadsides, clearings, and disturbed forests; it will also move into Garry oak meadow ecosystems and coastal bluffs.

Impact

Scotch Broom is considered toxic to wildlife, and displaced native species in open ecosystems. It spreads rapidly due to large numbers of seeds (up to 35,000 per plant!) that linger in the soil seed bank for decades, and fixes atmospheric nitrogen into the soil, favouring non-native species.  High densities of plants can smother wildflowers, prevent tree regeneration, and increase wildfire danger.

Management

Cut broom anytime before it starts producing seeds (usually before the end of June), ideally when it is in full bloom. Cut the stem as low to the root crown as possible.  All flowering individuals in a population should be removed annually.  Patience and persistence are needed, as it will take at least several years to several decades to exhaust the seed bank in any given site.

Small plants that are not yet producing flowers can generally be left alone, as young broom has a high mortality rate.  Wait until they bloom, then cut them.  Broom without seed pods that has been cut can discarded in the forest in shady areas, provided it is located where it will not result in a fire hazard.  Broom with seed pods should be burnt.

Our Experience

With many years of concerted effort, we have found that even overwhelmingly large populations of Scotch broom can be controlled and eliminated.  Consistent annual cutting is the key, as missing even one year can lead to significant setbacks.  Broom should be removed whenever possible from sensitive ecosystems such as Garry oak woodlands and coastal bluffs.

Uses of Harvested Scotch Broom

Plant can be used to create yellow and green dyes. For large plants, the woody stems are especially strong, and can be used in woodworking and crafting. Flowers and flexible branches can be used to create summertime wreaths and bouquets.

Spanish Bluebells (Hyacinthoides hispanica)

Description

Perennial herb from a scaly, egg-shaped, 2- to 3-cm long bulb; flowering stems erect, 20-50 cm tall, smooth. Blue bell-shaped flowers occur in terminal clusters.

Habitat

Spanish bluebells are native to the Iberian Peninsula. They are an escaped ornamental plant found in roadsides, forest edges, and Garry Oak ecosystems.  On Galiano Island, they are uncommon but occasionally established on coastal bluffs and Garry Oak ecosystems.

Impact

Spanish bluebells compete for space with native plants in Garry oak ecosystems. They are incredibly difficult to remove from a site once they’ve established. Left on their own, they will quickly form a monocultural colony in just a matter of years.  They can be mistaken for the native wildflower camas (Camassia spp.).

Management

Dig out the bulbs to remove individual plants, ideally prior to flowering (usually April – May). It may take several years of removal to be successful. Dry plant remains in the sun or in a garbage bag for a year before composting or discarding in the forest in a shady area.

Our Experience

Remove individual plants before they form large colonies.  Avoid planting this pretty but problematic ornamental species.

Spurge Laurel (Daphne laureola)

Factsheet

• Invasive Species Council of Metro Vancouver

Description

Evergreen shrub with thick, waxy leaves growing up to 1.5 m tall.  White fragrant clusters of flowers are followed by small black berries.  Stems are smooth, green to grey-brown.

Habitat

This Eurasian ornamental has escaped cultivation into forests, fields, coastal bluffs, and Garry Oak ecosystems.  It thrives in full sun, part shade, and full shade.  On Galiano Island, it can dominate the forest understory on rich sites and move into old agricultural fields and pastures.

Impact

Spurge laurel is poisonous, harmful to the touch, and outcompetes native plants in the forest understory.  It can also move into Garry Oak ecosystems and displace sensitive native species.

Management

Spurge laurel is highly toxic and should be handled very carefully.  Thick gloves and protective clothing are essential to avoid exposure to toxic sap.  Small plants can be hand-pulled; larger plants should be cut just below the root collar during or prior to flowering.  Repeat cutting are usually necessary over the course of several years to control or eliminate a population. Removed plant material should never be burned; instead, it should be bagged and discarded in a landfill, or dried out on an impermeable membrane and then discarded in the forest in a shady area, provided it is located where it will not result in a fire hazard.

Our Experience

As long as necessary precautions are taken to eliminate the risk of skin exposure, spurge laurel populations are fairly straightforward to manage.  Hand-pulling and cutting can proceed relatively quickly, and if performed on an annual basis can quickly control or eliminate a population.  Spurge laurel should be removed wherever it occurs.

Tansy Ragwort (Jacobaea vulgaris syn. Senecio jacobaea)

Factsheets

• Invasive Species Council of BC
• Garry Oak Ecosystems Recovery Team
• Capital Regional District

Description

Short-lived perennial flower between 20-120 cm tall. Flowers are yellow and daisy-like, arranged in a dense, flat-topped cluster at the top of a purplish stem. The leaves are highly lobed and ruffled.

Habitat

Tansy Ragwort is native to Europe, Asia, and Siberia. On Galiano Island, it is generally found in sunny, disturbed areas, such as pastureland, grasslands, and roadsides.

Impact

Tansy ragwort is poisonous to people and animals, and can cause potentially fatal liver damage if consumed. Alkaloids in the plant will taint the honey of bees, making it generally too bitter and off-colour to sell and consume. Tansy ragwort  spreads rapidly: one plant can produce 150,000 seeds, and the seeds can persist in the soil for up to 15 years.

Management

Hand-pull plants that are between knee-height and hip-height, ideally prior to flowering (usually end of June).  Pull from near the base to ensure that as much of the root is removed as possible and avoid re-sprouting.  When pulling plants that are blooming, it is recommended to cut, bag, and burn flower heads.  Younger plants can be ignored – the roots fragment much more easily than older plants during removal, and may even increase the rate of spread.  Pulled plants without flowers can be discarded in the forest in shady areas, provided they are located where they will not result in a fire hazard.

Our Experience

This species is a relatively recent introduction to Galiano Island, and has rapidly formed small populations along roadways and in disturbed areas across the island.  New populations are very easy to control as long as they are removed in a timely manner; larger populations take several years of persistent annual removal to eliminate.  Tansy ragwort should be removed wherever it occurs.

Canada Thistle (Cirsium arvense)

Bull Thistle (Cirsium vulgare)

Factsheet

• Invasive Species Council of BC

Description

Prickly, short-lived herbaceous perennials from long taproots, growing up to 2 m tall.  Profuse purple blooms are followed by fluffy seed heads that disperse in the wind.

Habitat

These Eurasian weeds are common on exposed soils.  On Galiano Island, they are common in forest clearings, roadsides, and disturbed areas.

Impact

Thick patches are unpleasant to move through once established and can persist, hindering native plant regeneration.

Management

Wear gloves and thick clothing to prevent cuts from prickles.  Small plants can be hand-pulled from the basal rosette; ensure that the entire taproot is removed.  Larger plants can be mowed and left on the ground prior to flowering.  Once plants flower, flower heads can be cut, bagged, and burned.

Our Experience

Thistles typically do not occur on a site unless it has been recently disturbed.  Prevent establishment of thistles by limiting soil disturbance.  Typically, a site that develops a thistle population will, over time, develop a cover of introduced grasses and/or shrubs.  These other species are often more important to control than the thistles themselves.

Yellow Flag Iris (Iris pseudacorus)

Factsheets

• Invasive Species Council of BC
• Invasive Species Council of Metro Vancouver
• Capital Regional District

Description

Aquatic perennial growing up to 1.5 m tall.  Large, flat, strap-like green leaves emerge from thickened rhizomes in a distinctive fan shape.  Long stalks end in showy yellow flowers in parts of three. Can be confused with cattails (Typha spp.), but cattail stem bases are round, while iris stem bases are flattened.

Habitat

Yellow flag iris is native to Europe, western Asia, and north Africa.  On Galiano Island, it is found in creeks and along the margins of lakes and wetlands.

Impacts

Yellow flag iris can outcompete native wetland vegetation, reducing habitat for many native species.  It can clog waterways, alter hydrology, and make livestock sick if consumed.

Management

To limit population spread, cut, bag, and burn flower heads to prevent seeding.  To remove plants, carefully dig out and remove rhizomes, making sure to reduce fragmentation.  Several passes will be necessary to remove most rhizome fragments.  Seed germination and re-sprouding are to expected post-removal, and can be managed using a heavy rubber mat (such as a pond liner) as a “benthic barrier”.  Apply the mat for at least 70 days to ensure that remaining seedling and fragments are dead.  Removed plant material can be dried out in the sun on an impermeable surface, then discarded in the forest in a shady and dry area, or burned.

Our Experience

Iris is very difficult to remove once established.  Small populations can be managed by removing flower heads annually.  Removal requires repeated digging in the muck to remove rhizomes.  The use of a benthic barrier post-removal will reduce the need for future removal activities.  Iris should be removed from native creeks and wetlands whenever possible, especially when it is upstream of bodies of water.