Protecting Ecological Services for the Credit River Watershed - Identifying & Conserving a Natural Heritage System

All inhabitants of the Credit watershed benefit from the ecosystem goods and services provided by its forests, wetlands, streams and meadows: provision of habitat; fisheries; forestry; pollination; water purification; microclimate regulation; soil formation and nutrient cycling; erosion and sedimentation control; and biological or pest control. Many of these services - valued at trillions of dollars globally - have no technological fixes, meaning they are critical for human survival.

Natural Heritage Systems - core features on the landscape (e.g., forests, wetlands), linked by natural corridors to allow species movement – allow ecosystem services to be maintained for posterity. They also preserve biodiversity, the variety of life forms that provide ecosystem services and the genetic resources utilized for food, medicine, shelter and clothing.

Credit Valley Conservation has embarked upon an exciting project utilizing Geographical Information Systems (GIS) mapping and biophysical data collected over years. This project, termed the Terrestrial Ecosystem Enhancement Model (or TEEM) will identify a Natural Heritage System for the Credit watershed. Following science based provincial policy guidelines, such a system will allow municipalities to identify and conserve natural spaces and their services for future generations.

How is such a Natural Heritage System identified? Aerial photos of the watershed are examined and the boundaries of natural features are digitized using GIS (see photo). Landscape ecology and conservation biology principles are used to identify priority areas for conservation: larger natural areas are better than smaller ones; greater habitat diversity is generally preferred over lower habitat diversity; natural spaces that are connected locally and to regional wildlife corridors are preferred over isolated spaces; high groundwater recharge areas are preferred over low recharge areas; and natural areas near streams are preferred over those farther away from streams. Finally, a map of priority areas and connecting links is produced – a Natural Heritage System.

On the Lookout for Dog-strangling Vine!

Dog-Strangling Vine - Flowers

A relatively new invasive species is calling the Credit River watershed its home: Dog-strangling Vine (Cynanchum rossicum). This perennial plant is native to Eurasia, and was reportedly brought to Ontario intentionally in the early 1900’s as an experimental stuffing for lifejackets. Although reports of Dog-strangling Vine are still relatively uncommon in the Credit River watershed, it is already a major problem in our neighbouring watershed – the Toronto and Region Conservation Authority – and elsewhere in the province.

Also known as Swallowwart, this invasive species is highly effective in establishing itself in a variety of sunny habitats -- both in urban and natural areas -- and is commonly found along roadsides and ravines. It is most easily recognized by its glossy oval leaves, purple flowers, and pod-shaped fruit which are similar to milkweeds. When ripe the pods emit scores of fluffy white seeds that are carried to new areas by the wind, although humans, pets and wildlife can also inadvertently move seeds long distances through their clothes and fur. It can grow very aggressively and will usually out-compete native plants for space, light and resources. In some areas it forms dense mats, and its tangled vine-like stems make movement through it very difficult; this is thought to have led to its grisly name.

Control methods for Dog-strangling Vine, both manual and chemical, are being investigated in other areas of the province for their efficacy. Taking a preventive approach by managing invasive species before they are established and widespread is the easiest control method of all. CVC is presently working on an Invasive Species Strategy involving many plants and animals, including Dog-strangling Vine. In order to help reduce the spread of this plant, residents are encouraged to refrain from picking or transplanting any specimens and to report any encounters to the CVC’s Natural Heritage Department at 1-800-668-5557.