Silvercreek Park Rehabilitation

The City’s Parks Operations and Forestry division has initiated a rehabilitation project in Silvercreek Park to enhance the health and integrity of the natural area by removing and controlling buckthorn. As part of this project, staff will establish native species using a phased approach to reduce the physical impact on the site (i.e., wildlife, aesthetics, soil erosion, and colonization by other invasive species).

Buckthorn

Common buckthorn (Rhamnus cathartica) and glossy buckthorn (Rhamnus frangula) are non-native, highly invasive shrubs that threaten the ecological integrity and health of the City’s natural areas. Buckthorn aggressively forms dense thickets, which suppress the regeneration of native tree and shrub species. The seeds of the buckthorn are widely dispersed by birds and germinate quickly to take over natural areas. Seeds can also remain viable in the soil for up to five years. Once established on the edge of a forest, plants will spread into the interior. Buckthorn plants have the advantage of leafing out earlier than most plants in the spring and can retain leaves into early winter (Converse 1984) which leads to shading out other ground vegetation. Eventually, the presence of Buckthorn will lead to a decline of native species and overall species diversity.

The Credit Valley Conservation lists common buckthorn as a Category 1 invasive. Plants in this category are top priority for control due to the threat to natural areas. It is also listed as a noxious weed under Ontario’s Weed Control Act. The goal of buckthorn control is to reduce their numbers and provide opportunities for native vegetation to become established. Control efforts can prove very difficult especially if the plants are well established and spread across large areas.

Plan

The City’s Parks Operations and Forestry division has begun removal of buckthorn in Silvercreek Park; north of the trail that connects Water and Municipal streets. The removal is taking place to eliminate the non-native, invasive species—a noxious weed listed in the Weed Control Act—and is a multi-year plan to restore this portion of natural area in Silvercreek Park. All removals will be carried out using mechanical and/or manual methods only; no herbicides will be used at this time. The removal work will be carried out over four years, depending on weather and any other unforeseen circumstances.

Buckthorn spreads quickly and threatens the health of our urban forests. Removal is necessary in order to preserve City’s natural areas and promote the establishment of native species. Site rehabilitation will be carried out in the following years due to the extent of buckthorn removal that will take place. Rehabilitation activities will include plantings of native trees, shrubs, and groundcover.

Map showing area of restoration work in relation to surrounding features (park, streets); 0.36 hectare area located north of the trail in Silvercreek Park nearest the cul-de-sac at the west end of Water Street.

Figure 1 Location Map

Control measures

There are various options for control and removal of buckthorn. It is important to select the method(s) most appropriate for the circumstances such as environmental sensitivity, available resources, and the desired outcome, to name a few. The most commonly used methods are mechanical (cutting, girdling, pulling and excavation) and chemical or a combination of both. Each method has its advantages and disadvantages. While all methods could be considered for this area, only mechanical controls will be used at this time on the Silvercreek site.

Map showing details of 5 phases of removal and restoration work as well as one area with trees to be preserved. A table lists the timing of activities to take place in each of the 5 phases.

Figure 2 Removal areas and related activities

Rehabilitation

Replanting the understory, once the buckthorn is removed, with native shrubs, trees and groundcover suitable to the site conditions is essential in the rehabilitation process and to minimize impacts to wildlife, prevent erosion, prevent the re-establishment of buckthorn and reduce the visual impact for park users.

Monitoring

Removal of buckthorn and its seed bank requires a long-term commitment. A continued effort to remove young buckthorn plants will be required as they emerge over the next several years.

Safety

Access to trails in the immediate work area will be restricted during activities. For safety reasons, residents and trail users are asked to avoid the work area, which will be clearly marked.

Call to action

Property owners can do their part by removing invasive and noxious weeds from their property and replacing them with native or non-invasive species.

Related links

For more information or to volunteer

Dave Beaton
Supervisor, Trails and Natural Areas
Parks Operations and Forestry
519-822-1260 extension 2761
dave.beaton@guelph.ca

Timea Filer
Urban Forestry Field Technologist
Parks Operations and Forestry
519-822-1260 extension 3352
timea.filer@guelph.ca