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Invasive Forest Plants
Threats and Management
What is an Invasive Species?
Native:• A species that has existed in a given area prior to European
settlement
Non-native:• A species that has been introduced from another geographic
region to an area outside its natural range.
Invasive: • Usually a non-native species whose introduction does or is
likely to cause economic or environmental harm or harm to human health.
Some definitions…
What is an Invasive Species?
Flora
Fauna
Aquatic
Terrestrial
Terrestrial
Aquatic
Why should we control them?• Biodiversity
– Native or indigenous plant & animal species have evolved inter-dependently over aeons
– Invasive species remove native species through competition & predation, destroying those interdependent links that tie entire ecosystems and communities together.
• Biodiversity
– Native or indigenous plant & animal species have evolved inter-dependently over aeons
– Invasive species remove native species through competition & predation, destroying those interdependent links that tie entire ecosystems and communities together.
Biodiversity? So whatBiodiversity? So what
Ecological goods and services: the creation, Ecological goods and services: the creation, regulation & purification of air, water & soil regulation & purification of air, water & soil and food, medical & economic products & and food, medical & economic products & supports cultural/spiritual and recreational supports cultural/spiritual and recreational valuesvalues
Intrinsic value: Just because its there, Intrinsic value: Just because its there, intangiblesintangibles
Why should we control them?
Other Impacts
• Human Health and Safety• Infrastructure• Impacts to natural resource dependent
industries (agriculture, forestry, fishing….)
Real life impacts
Forest Management• Direct tree loss
– Pests (ALHB, EAB, Gypsy moth) – Tree diseases (Beech bark disease, Pw blister rust..)
• Forest management activities– Suppression of competing vegetation becomes problematic
($$)– Soil disturbance = new invasions– Opening up canopies can lead to suppressed
seed banks germinating– Invasive species outcompete and suppress
natural regeneration
• Productivity– Invasives can reduce growth rates through shading, and
allelopathic compounds/effects (e.g. garlic mustard)– E.g. 35 yr. rotation vs. 20 year ??
Agriculture
• Pasturelands– Poisonous plants– Range management
and loss to invasive plants
• Crop– Increased use of
herbicides
Wildlife appreciation, hunting…
Encouraging viewing/hunting opportunities• Diverse habitats provide for a diversity of species that may
require that habitat(s) for breeding and other life functions• Diverse food/foraging opportunities• Impeded areas reduce feeding opportunities (e.g. hunting-
grouse, wild turkey)
Several invasives species can be poisonous to people (Hogweed, Wild parsnip, Hedge parsley….)Can impede walking (dense tangles, burs…) and increase trail maintenanceAquatic species…boating, reduces oxygen levels, invertebrate community impacts…fishing
CVC Monitoring Program
• Upward trend Weedy (-3) species
• 2 problematic non-native species: -European Buckthorn-Garlic Mustard
• Upward trend Weedy (-3) species
• Proportion of native species decreasing
Forest Wetland
What can we do?
Key first steps to managing for invasive species
• Identify and know your invasive species• Take Action
– Prevention– Control– Monitoring
Know The Culprits
Main culprits in the Forest
Actions (Prevention and Control)
• Common buckthorn• Garlic mustard• Non-native bush honeysuckles• Dog-strangling vine
Invasive Species in the ForestFlora (top 10) Pests/Diseases
Common buckthornGarlic mustardDog-strangling vineCommon reedGiant hogweedNon-native honeysucklesNorway mapleGoutweedRough manna grassPeriwinkle
Asian long-horned beetleEmerald ash borerFall canker wormGypsy mothOak declinePine weevilSirex wood waspPine shoot beetleForest tent caterpillarWhite pine blister rustBeech bark diseasesButternut cankerDutch elm diseases
Prevention- Invasive Plants
• Monitor for presence• Yard waste or invasive plant disposal • Clean mud, seeds, and plant parts from
machinery before moving it to a new location
• Minimize soil disturbance (winter operations, best practices…)
• New plantings- be careful of your sourcing for mulch
• Plant sourcing- invasive vs. native vs. cultivar• Public Land- trail monitoring
Control
Options for the main problematic species
• Common buckthorn• Garlic mustard• Non-native bush honeysuckles• Dog-strangling vine
**CVC has a much larger list with best methods for each species
Common Buckthorn
Reach 20-25 feet in height and 10 inches in diameterTwigs end
in pointed,stout thorns
Introduced to North America in the late 1700’s, but did not become widespread until the early 1900’s. In the past buckthorn has been widely cultivated for hedges.
It readily invades a variety of natural areas. Once established can spread very quickly creating a thick cover that will shade out native shrubs and plants.
Egg-shaped leaves have distinct veins that are curved towards the leaf tip
Common (European) buckthorn (Rhamnus cathartica)
Bark: orange inner bark
Fruit has berries becoming purplish / black in late summer, berry <1cm
A look alike Is native alternate dogwood
Complex Relationships
=
+
Control• Persistent seed bank (5-6 years)• Well established populations can mean 5-6 years of
control (Initial removal then monitor and treat as needed)
Methods• Hand pulling of small shrubs (disturbed soil in well
established areas could allow for seed bank germination)• Herbicide and timing
– ‘Mash and squirt’– Garlon (30% basal bark) (5% foliar)– Round-up (80-90% cut stump or frill and squirt)
(5% foliar)
Garlic MustardGarlic mustard (Alliara petiolata)
A biennial herb with plants that survive the winter producing flowers in the 2nd year.
Garlic mustard was introduced by early settlers from Europe.
Once introduced to an area, garlic mustard out-competes native plants
Allelopathic species that kills mycorrhizal fungi that many native plants and trees require for growth
first year plants
second year plants
Control• Persistent seed bank (6-7 years)• Well established populations can mean 6-7years of control
(Initial removal in year 1 and 2, then monitor and treat as needed)
Methods and timing• Solarisation (not recommended)• Hand pulling in lightly infested areas• Weed whipper in heavier areas (2 cuts per year repeated for
several years. 2nd cut 2-4 weeks later) (first cut approx. early- mid June)
• Biocontrol 4-5 years away (may only be effective at certain sites)
• Herbicide and timing– Round-up (3% foliar applied to basal rosettes in fall or
spring). Can also be sprayed on warm (>10 degrees) winter days where no snow pack exists. Garlon or Amitrol slightly more effective.
Dog-strangling Vine
aka Black Swallowwort and Pale Swallowwort (Cynanchum rossicum and C. louisae)Members of the milkweed family native to Ukraine, Russia, and Mediterranean region.
A perennial plant that grows 1 to 2 m high by twisting on to trees and other plants.
DSV are very aggressive smothering desirable species.
Once established, pure stands of DSV suppress the establishment of natural tree regeneration in our forests as well as woodland and meadow plants.
Spreading
dogbane
Control• Well established populations often mean several years
of control (Initial removal in year 1, then monitor and treat as needed over next few years)
Methods and timing• Solarization in localized areas (2 years)• Hand pulling in light areas where plants are young and
soils loose.• Herbicide and timing
– Round-up (3-5% foliar applied at onset of flowering). Often need two sprays in one season over several years. (22% for hand wicking in sensitive areas). Garlon and Arsenal may be more effective.
– Dichlorprop (3% foliar)
Non-native honeysuckles
The alien honeysuckles compete with native bush honeysuckles for pollinators, resulting in reduced seed set for the native species.
Shade out native plants and regeneration.
Impacts on native songbirds through increased nest predation.
Alien bush honeysuckles Amur Lonicera maackii,Morrow’s L. morrowii,Tatarian L. tatarica,Bell's L. x bella, hybridDwarf L. xylosteumFragrant L. fragrantissimaStandish's L. standishii
Japonica
MorrowiiTatarica
Maackii
Non-native honeysuckles
Control• Persistent seed bank (4-5 years)• Well established populations can mean 4-5 years of
control (Initial removal then monitor and treat as needed)
Methods and timing• Hand pulling (roots can sucker in larger shrubs, so may
have to deal with resprouts). Soil disturbance in established areas may expose the seed bank.
• Herbicide and timing– Garlon (30% basal bark) (5% foliar). Late season applications
not as successful– Round-up (80-90% cut stump or frill and squirt)(5% foliar)
Now….Where to begin?
• Early invasions (and seed sources)• Species aggressiveness• Protect rare species• Protect rare community types
Refine project selection with costs:• Is there a cost effective method available?• Restoration costs?
Example
Restoration/Rehabilitation Considerations
• Many invasive species maintain seed banks• Many sites if not impaired by years of invasion will
regenerate naturally > only monitoring of seed bank is required (varies by species)
• Impaired sites may have altered soils, lack regeneration and rehabilitation will be required. Strategies vary by species. Examples:– May have to delay restoration until seed bank is dealt
with. Consider cover crops as bridge between removal and planting….mulch in smaller areas
– Soil remediation– Replanting (tree/shrubs, seed mixes)
ExamplesCase Study 1: Common buckthorn removal
ExamplesCase Study 2: Norway maple removal
Monitoring
• Monitor, Monitor…Monitor• Begin the cycle with monitoring for
Invasive Species (prevention and detect) and end it once they are removed and area is restored.
• Doesn’t have to be elaborate• Photo monitoring, trails• Casual walks of the woodlot
Questions
Rod Krick, Natural Heritage EcologistCredit Valley Conservation (905) 670-1615 ext. 263 [email protected]
Invasive Species Websitewww.creditvalleyca.ca/invasives
