Introduction
The City needs to adopt a linkages map to:
- fully protect our Natural Heritage System,
- complete the Rural Hamilton Official Plan, and
- resolve an Ontario Municipal Board appeal of the linkage policies in the Rural Hamilton Official Plan.
What are the Natural Heritage System & Linkages?
The Natural Heritage System:
- is a system of connected natural areas which provide habitat for plants and wildlife and contribute to a healthy community
- consists of Core Areas (the most significant natural features and their buffers) and Linkages
Linkages:
- are smaller, supporting habitat patches that are beside or join Core Areas
- provide movement opportunities for wildlife and plants
- include smaller areas of forest, meadow, wetland, and thicket
Why is it important to identify and protect linkages?
Linked natural areas:
- are required to be protected in provincial plans (Provincial Policy Statement and Greenbelt Plan)
- create wildlife and plant movement corridors that are vital to a healthy, resilient ecosystem
- allow plants and wildlife to move across the landscape and interbreed, which is important for maintaining biodiversity and ensuring the long-term survival of species. Isolated habitat patches can lead to local extinctions of species over time.
- provide opportunities for species escape and movement after environmental disturbances like fire and drought.
- provide a range of habitats and refuges for wildlife and plants. As the size of remaining natural areas decreases, it becomes more important to maintain linkages between habitats.
How were Linkages mapped?
Linkages were mapped by first identifying habitat patches (using 2009 air photos) 0.5 hectares or more in size. These patches included woodlands, meadows, wetlands, and thickets. Hedgerows were generally not mapped. Although many hedgerows were not mapped, there are policies in the new Rural Hamilton Official Plan requiring them to be retained wherever possible.
After habitat patches were mapped, ecological corridors were identified. Corridors are defined as larger, landscape-level movement pathways that wildlife and plants use to travel across the region. Most corridors follow streams, but some also run along the escarpment and Lake Ontario shoreline. They can also include disturbed areas, like hydro corridors, rail trails, and other easements.
Once the corridors were identified, any habitat patch that touched the corridor was included as a Linkage. The purpose of this method of mapping was to ensure that only those patches contributing to wildlife and plant movement or directly supporting the ecological functions of Core Areas were included as Linkages.
Once a draft map was prepared, City staff reviewed it to ensure that the ecological principles of corridor design were followed. During this review, City staff considered the following principles, removing Linkages that did not meet these principles:
- Generally, wider linkages are best.
- Linkages that form continuous connections with Core Areas are better then those which are broken. However, even broken Linkages will provide ‘stepping stones’ for species movement across the landscape.
- The ecological function is considered. For example, what species are likely moving along the corridor and what are their requirements?
- Linkages and corridors should meet the movement requirements of the most demanding species.
- Preserving as many corridors as possible will provide alternative routes for wildlife movement.
- Linkages with high habitat diversity are preferred; they should provide a range of habitat sizes and types.
- Linkages with minimal human disturbance are best.
- Linkages associated with water (streams, headwaters, recharge and discharge areas, wetlands) are important.
- Linkages that round out the shape of a Core Area and minimize its edge are best. Linkages that increase the size of a Core Area are preferred.
- Include wider sections (nodes) in a corridor to compensate for narrow width and to provide refuges for wildlife.
How are Linkages Protected?
Policies in the Rural Hamilton Official Plan to protect Linkages already exist. They have been adopted by Council and approved by the Ministry of Municipal Affairs and Housing (MMAH), but are under appeal to the Ontario Municipal Board. (See handout for policy details.)
The missing piece of linkage protection is a Linkage map.
Habitat restoration through programs such as the Hamilton-Halton Watershed Stewardship Project which provide assistance to landowners who wish to enhance streamside vegetation and plant trees on their property.
Conclusion
The City of Hamilton has prepared draft Linkage mapping for its Natural Heritage System in the Rural Hamilton Official Plan. Staff is currently seeking public and agency comments on the draft map due on October 14, 2011. Once all comments have been reviewed, the map will be revised. The final map will be presented to Council as part of an Official Plan amendment to the Rural Hamilton Official Plan.
Please provide your comments to Cathy Plosz (contact information top right of page).