Tony Pus
Oak Savannah near Bloor St.
Karen Yukich

Oak Savannah

About 1/3 of the park’s natural environment consists of nationally rare oak savannah, an open, park-like landscape that contains widely spaced black oaks, scattered low shrubs and a rich variety of prairie grasses and wildflowers.

Of the over 2 million ha of prairies and savannahs that once covered southern Ontario, less than 2,100ha (0.1%) remain today.

The Ontario Ministry of Natural Resources has identified approximately 44 hectares (110 acres) of the park's natural environment as significant oak woodlands. Experts consider the oak savannah at High Park to be "continentally significant" because it occurs near its northern limits in the park and because of the size, nature and characteristics of the remnant ecosystem.

High Park shelters 41 rare plant species, 32 of which appear in the savannah. Among these plants are nationally rare woodland fern-leaf, wild lupine and cup-plant.

Savannahs are dependent on periodic fire to maintain their open character and rich variety of plant species.

What are Savannahs?

Before the arrival of the first European settlers, the landscape that is now Southern Ontario was dominated by vast areas of forest. The forest cover was occasionally interrupted by two principal types of tallgrass ecosystems - prairie and savanna. Although these open habitats characterised the landscape in the Midwestern United States and parts of the prairie provinces, only scattered patches were found further east, primarily in the south-central and southwestern parts of Ontario.

Lupines on the Oak Savannah
Bob Yukich

Because they were already open, relatively dry, and attractive sites, prairies and savannas were prime targets for settlement. The great expanses of prairie on the great plains and most of the smaller patches in the northeast were rapidly converted to agriculture or urban land uses.

Now, only very small isolated remnants of the original habitats remain. Coincidentally, some of these have survived in older urban parks, and Toronto is blessed with several of these rare treasures.

The two tallgrass community types are quite distinctive. Prairies are open treeless areas dominated by grasses and forbs (wildflowers). In contrast, a savanna (also spelled savannah) is essentially an open woodland that combines prairie and forest features. Technically speaking, a savanna is a tallgrass community with 25-35 percent tree cover, according to the Ecological Land Classification System for Southern Ontario.

The type of savannah is defined by the dominant tree species. In North America the most common types are pine and/or oak savannas, since these trees tolerate dry sandy soils and are fire-resistant.

Source: Toronto Savannas brochure

Download a map of high quality savannah areas in High Park (pdf)

See also:

Article in SNAP Sept/2013

The Oaks of High Park, Prairie Grasses, Natural History of High Park

A Survey of the Prairies and Savannas of Southern Ontario

Oak Savannas: Characteristics, Restoration and Long-Term Management (Wisconsin)

A Garden of Rarities, Lorraine Johnson, ON Nature magazine, 2009

Toronto Once had a Prairie! article by Frank Remiz in Toronto Field Naturalist newsletter, February 2017 (more about Toronto Field Naturalists)

Take a Guided Tour of the Black Oak Savannah with Sam Benvie

Take a tour of the Black Oak Savannah and High Park ecosystem with Sam Benvie. Prepared for Ecology and Sustainable Landscapes (CKLA 400), an online course offered at Ryerson University.

Watch it on YouTube or Google Maps or this webapp.

Rare Plants of the Endangered High Park Black Oak Savannah

For more  information about this Volunteer Stewardship Program Guidebook, please see this poster (pdf) or Rare Plant Book Page

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Content last modified on September 11, 2017, at 04:02 PM EST