Ministry of Labour and Citizens' Services

Wildfire Response and Recovery

Post-fire Invasive Plant Research and Management
in Okanagan Mountain Fire Area

Lisa Scott

Lisa Scott is a registered professional biologist and is actively working in the Southern Interior as an environmental consultant. The principal components of this work have included habitat assessments, habitat restoration and enhancement, environmental impact assessments and invasive plant management. Of particular significance is her involvement as the Chair of the South Okanagan-Similkameen Weed Committee for five years, as well as the Coordinator of the affiliated SOS Weed Education and coordination Program for eight years.

Chris Wood

Chris Wood is a biogeographer who received his Master of Science from the University of Victoria in physical geography in 2001. Since moving to Penticton 3 years ago, Chris has been working with local biologists, government ministries, and conservation organizations to provide GIS mapping and modeling for conservation and stewardship initiatives.

Presentation Summary: In 2004, the South Okanagan-Similkameen Weed Committee identified a need to invest substantial efforts on weed management (inventory/mapping, treatment, monitoring and research) in the locations of three fire-impacted areas in the South Okanagan: Anarchist, Vaseux and Okanagan Mountain. This presentation focuses specifically on work conducted within the confines of the Okanagan Mountain Fire.

The Okanagan Mountain Fire that occurred in August 2003 undoubtedly changed the associations between native and introduced plant species. Soil exposure due to intense heat from the fire and soil disturbance created by earth moving equipment (e.g. during construction of fire guards, creation of new roads or vehicle turnabouts) created an ideal seedbed for weed establishment. Salvaging logging and increased traffic due to an upsurge in tourists and recreationists created additional soil disturbances and undeniably contributed to weed spread. Consequently, effective weed management became an even greater concern in this fire-impacted location.

Finances were secured through the Inter-Ministry Invasive Plant Committee and other partners, and a task team was formed to develop a post-fire strategy to deal with the expansion of established weeds and the potential invasion of new weed species. Detailed inventory and mapping was conducted for thirteen target invasive plant species, although the primary species of concern is tansy ragwort (Senecio jacobaea). This provincially noxious weed is a primarily coastal species, with the only known infestation in the Southern Interior occurring in the Chute Lake area, northeast of Penticton. This particular infestation also happens to be the largest infestation in the entire province.

Priority weed species were treated using a combination of herbicide spot-treatment and cutting/bagging. One hundred and fifty permanent vegetation plots, along five transects, and fifteen photopoints were established, which will be re-measured and re-photographed in years 2, 5 and 10 post-fire.

A predictive model for tansy ragwort was developed to assess the risk to native plant communities from non-native plant invasions and model the spread of this species across the landscape using GIS, plant demographic data and population matrix models. Our risk model incorporates biophysical habitat features to generate a map with various levels of risk (e.g. very low, low, medium, high and very high risk).

The knowledge gathered through this multi-year project will be of considerable value to land managers and will be applicable to landscapes across the province. This project aims to use science to define clear ecosystem-management objectives, focusing specifically on the control of invasive plant species using a long-term approach to assist the natural recovery of the native plant community.

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