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.
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.
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)
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.
Rare Plants of the Endangered High Park Black Oak Savannah