Download Weed Invasion in the South Okanagan

Weed Invasion in the South Okanagan
L. Scott
D. Ralph
RR #3, Site 38, Comp. 24, Summerland, BC, V0H 1Z0, Canada
[email protected]
British Columbia Ministry of Agriculture and Food
162 Oriole Rd., Kamloops, BC, V2C 4N7, Canada
[email protected]
ABSTRACT
Plant invasions are a serious global threat to natural and managed habitats. In British Columbia, over 20% of the
vascular plants have been introduced. Weeds are adapted to a wide range of environmental conditions but occur
most often in disturbed soils and depleted rangelands. They compromise land values for wildlife, livestock,
agricultural crops, recreation and aesthetics. Prolific seed production, varied dispersal mechanisms and an ability
to tolerate severe stress conditions contribute to the ecological success of weeds and their often rapid colonization
of habitats. The current assessment focused on several plant families and included terrestrial, wetland and aquatic
plants. The earliest records for these species was based primarily on information gathered from herbariums at the
Royal British Columbia Museum and the University of British Columbia. The first known collections in British
Columbia for most of the weeds identified in this assessment were between the end of the nineteenth century and
soon after the turn of the century. The Sunflower Family: Asteraceae (Compositae) is the largest family of weeds
occurring within the South Okanagan. The knapweeds (Centaurea) are one of the most well known and ecologically
harmful groups in this family; they have caused severe loss of production, environmental quality and aesthetics on
thousands of hectares of urban, agriculture, forest and recreation lands. However, new colonies of species such as
sulphur cinquefoil, Dalmatian toadflax, leafy spurge and rush skeletonweed are establishing at a phenomenal rate
in the Okanagan and many infestations are reaching environmentally severe size and density. The potential
distribution of these species is highly significant and must be addressed. Emphasis should be placed on prevention,
awareness, early detection and eradication where possible; these are the most practical, economical and effective
means of weed management where weeds have not currently been introduced or established.
L. M. Darling, editor. 2000. Proceedings of a Conference on the Biology and Management of Species and Habitats at Risk, Kamloops, B.C., 15 - 19 Feb.,1999. Volume Two.
B.C. Ministry of Environment, Lands and Parks, Victoria, B.C. and University College of the Cariboo, Kamloops, B.C. 520pp.
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Proc. Biology and Management of Species and Habitats at Risk, Kamloops, B.C., 15–19 Feb. 1999.