According to the Rouge Park Ecological Survey (1990, Ontario Ministry of Natural Resources), the lower Rouge Park ecosystem is home to:
The Rouge ecosystem has also been recognized because it is one of 36 critical Carolinian sites remaining in Canada, and it boasts:
Of particular interest are:
This biodiversity would be considered outstanding anywhere, and is all the more significant considering the location of the park in the most heavily developed region of Canada, the Greater Toronto Area.
Pre-Settlement Rouge Forests
Rouge valley slopes supported forests in pre-settlement times that are similar to those today. On moist, north-facing slopes, Galbraith (1833) noted mixed forests of hemlock, maple, white pine and basswood. Drier, south facing slopes had forests of white pine, oak and beech.
Although sizeable First Nation farm clearings were made hundreds of years earlier, Ontario Land Surveys (1793) of the Rouge area describe almost continuous forest cover with only occasional openings due to windfalls and wetlands.
On the tablelands, moist uplands with clay or loamy soils supported deciduous forests of sugar maple, beech, basswood and white elm; and mixed forests of hemlock, white pine and hardwoods. On sandy or dry knolls, red oak, white oak and white pine were abundant. Scattered throughout the deciduous stands were large white pines rising above the deciduous canopy.
White pine was noted to be a dominant species in approximately 36% to 40% of the tableland forest areas, probably in part due to the favourable conditions for pine regeneration provided by native clearing, burning and farming activities hundreds of years earlier.
Just south of Steeles Avenue, Galbraith (1833) described a mixed forest of White Elm, Black Ash and maple. White cedar and basswood were described on the Rouge River bottomlands; a mixed forest of hemlock, white cedar, maple and basswood was found in the Little Rouge Creek bottomlands; a deciduous bottomland forest of maple, basswood, and white elm was found along a tributary of Little Rouge Creek; a deciduous swamp of black ash and white elm was found near the headwaters of a tributary of Petticoat Creek, and a white cedar conifer swamp was found along Morningside Creek.