Option C – Targeted Approach

Direct Administration to contract out a targeted approach for the removal of Wild Parsnip and Tree of Heaven along the east bank of Little River. Removals would have to be repeated for several years and there remains the possibility of re-establishment if future maintenance works do not take into consideration invasive species control.

Wild parsnip can be controlled by cutting the plant just below the soil surface. Mowing will reduce seed production but it will not kill the plant or reduce the established Wild Parsnip population. Herbicide is effective at controlling Wild Parsnip, however, broadcast spraying will destroy all the vegetation sprayed, including desirable species, which results in exposure of bare ground. This will usually lead to the establishment of new weeds, soil erosion and ditch bank destabilization. A targeted use of herbicide would be appropriate. It may take several years of removals to eliminate Wild Parsnip from targeted areas.

Tree of Heaven is not a hazardous plant. It can be controlled through selective cutting and the targeted use of herbicide.

Option D – Educate and Monitor

Educating the public and City personnel on local invasive species, including best management and planning practices to reduce their spread could help prevent further outbreaks. Education could be done through a variety of methods, for example the creation of a video with Communications, and an update on the Corporate Website. Future projects and maintenance could be screened to identify any ecological impacts from construction and maintenance works.

Monitoring of areas of removal is recommended to track the increase or decrease of invasive species. Even if plants are removed there is still the possibility of the species becoming re-established through seed dispersal by wind, water, transported by wildlife, people, and equipment.

Summary

For the current management of the identified invasive species on the east bank of Little River, a Targeted Approach would be recommended. A City-Wide Invasive Species Management Strategy would be recommended to more effectively manage and control invasive species issues across the City, reduce future costs and protect our environment.

Risk Analysis:

Invasive species have a variety of negative impacts on our environment. They reduce biodiversity which negatively impacts the health and function of our ecosystems and puts already stressed native species under further strain. Some invasive species also present health and safety risks to the public if the public comes into contact with them.