Managing Invasive Plants to
Protect
Biodiversity
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Getting started
• What species of non-native plants are
already established?
• Which interfere with achieving our goal
for the site (e.g. preservation of
biodiversity)?
• What part does each plant play in the
altered ecosystem?
• Developing a strategy
www.invasive.org/gist/products/plans/W
eedTemp.pdf
Site: unstable slope; exposed soil
Species: reproduces largely from rootstock, also seed; dispersed
by ejection (to 15ft); seeds can float; seed viable 5-8 years;
extensive root system with large energy reserves (manual
control ineffective)
Leafy spurge isolated patch
Context: bounded on south by extensive caragana thicket
Management: Leave and monitor; do not remove caragana as
preventing L. Spurge spread towards river; cut and remove
flowers to deplete seed bank 5-8 yrs; check area for new
colonies and remove by hand-pulling (only effective within first
two years of establishment)
Mapping the
distribution and
abundance of
target species
2009
2010
2011
Weeding – control or eradication?
Where to start?
Tartarian honeysuckle
survey shows prevalent in all ecosystems
except willow
Site: start control efforts in least affected
ecosystem i.e. riverine
Species: reproduces by seed; seeds
germinate in spring (do not remain
viable for long periods); seedlings
establish in sparse vegetation, often
under tall shrubs or trees; once
established can tolerate deep shade;
shallow rooted; sprouts vigorously if
cut
Management: actively search for young plants in appropriate
habitat; remove shrubs <3 yrs by hand-pulling; cut older plants
repeatedly June to Oct to deplete root reserves
Volunteers’ abilities and
interests vary
When manual removal not
possible/effective…
plant
energy
reserves
possible
winter kill
plant
repeatedly
cut back
J F M A M J J A S O N D
time of year
Use of herbicide?
Doing nothing…?
Site: deep shade
(under mature
balsam poplars)
example: isolated patch
of Oxeye daisies
Species: prefers sun
but can tolerate
partial shade; likes
disturbed ground;
reproduces by primarily by seed but also by rhizomes; flowers
June-Aug; seed dispersed close to parent plant; most seeds
germinate in spring; seed viable c.6 years
management (?):
patch is in a shady location – may die out on its own –
monitor; prevent further disturbance of ground; cut flowering
stems in June to prevent seed production; check around patch
for new seedlings in spring and pull… for 6 yrs!
example: alfalfa – survey shows
widespread along trail edges
Site: trail edges – disturbed ground (disturbed by mowing,
erosion and compaction)
Species: needs sun; prefers deep, well-drained, nearneutral soils; nitrogen fixer; very deep root system (39m)
Management: leave, as not practical to prevent disturbance
along trails; does not appear to be invading interior; may
be preventing establishment of ‘worse’ invasive plants
(out-competing and increasing soil fertility
Working with
the City (and its
priorities…)
Importance of monitoring
Looking out for new invasive species
• What to look out for - City list vs. site list
• New to Alberta – EDDMapS www.eddmaps.org
Keeping track…
END
Weaselhead/Glenmore Park Preservation Society acknowledges
the support of Nature Calgary, the Alberta Stewardship Network,
TD Friends of the Environment Fund, and the Alberta
Conservation Association
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