A significant forest-valley-river complex in the very eastern periphery of the Carolinian life zone. Contains a variety of river valley vegetation types (Eagles & Beechey, 1985).
Includes: Rouge River Central Woodland Valley Complex: situated along Little Rouge Creek adjacent to the Rouge River in Metro Toronto. Its southern boundary abuts Hwy 2 and its northern edge, a transmission corridor (Hanna, 1984 in Eagles & Beechey, 1985).
Rouge River Central Woodland Valley Complex (Hanna, 1984 in Eagles & Beechey, 1985):
Typical vegetation types are willow-Manitoba maple- cedar bottomland, red oak-hemlock-white cedar slopes and hemlock-white pine-sugar maple-beech-black cherry-red oak tableland.
Lower Rouge Marshes (Hanna, 1984 in Eagles & Beechey, 1985):
Lying just upstream of the mouth of the Rouge River, they contain the following marsh/vegetation types: 15% open water, 42% open water with floating and submergent aquatic vegetation, 36% cattail marsh, and 5% graminoid marsh. The wooded bottomlands at the base of the slopes contain willow-cottonwood-balsam poplar-Manitoba maple-dogwood-ostrich fern with black maple, sycamore and ash in some places. The deciduous ravine slopes lead to residential development on the tablelands. The forested slopes on the east bank of the Rouge River south of Hwy 401 are notable for a stand of native red oak, white oak and white pine. The trees range in age from 70 to 143 years. Many rare prairie plant species are present. The area was historically a sandy pine and oak woodland or 'barrens'.
The Lower Rouge River Nature Reserve Zones (Varga, 1984 in Eagles & Beechey, 1985):
The regionally unparalleled number of community types in the Rouge is attributable to wide variations in soil moisture, microclimate and successional status. The extensive tablelands, bottomland terraces and valley slopes characterized by well drained moist soils are dominated by mature forests of sugar maple and to a lesser extent beech-sugar maple and eastern hemlock-sugar maple. Hemlock forests are essentially confined to northfacing slopes and adjacent tablelands, while beech prefers dependably moist southern aspects. In younger forests, paper birch is a strong associate with these dominant trees. Other tree species prevalent in moist forests include: white ash, black maple, bitternut hickory, butternut, white elm, ironwood, basswood, yellow birch and white cedar. The last two species are most significant in hemlock forests, with white cedar occasionally surpassing hemlock in importance on steep slopes.
The excessively drained areas on isolated knoll tops, valley rims and south facing slopes are dominated by red oak-sugar maple forests or by younger early successional forests of paper birch and large-toothed aspen. Important tree associates include; red maple, black cherry, white oak and white pine. In contrast, an excessively drained but cool tributary valley supports a white pine-hemlock-white cedar forest, more typical of stands on the Canadian Shield.
The poorly drained and periodically flooded first bottomland terrace, between 1 and 2 meters above the river is dominated by forests of Manitoba maple, white cedar and crack willow, with ostrich fern forming a lush understory cover. Frequent associates include: white elm, balsam poplar and white ash. In the northern portion of the valley an occasional terrace 4 meters in height sustains rich black maple-sugar maple forests.
Rouge River Valley (J. Riley in Eagles & Beechey, 1985): This area represents the only vegetated ravine-interfluve-ravine marsh complex of its size (625 ha) east of Oakville. The excellent examples of shoreline marsh (Lake Ontario), ravine oak forests, white pine forests, shoreline beach associations, and horsetail meadows provide suitable habitat for a myriad of plants and animals. This high number of remnant communities allow for the existence of over 660 species of vascular plants. The condition of the site is exceptional despite the near-urban location because of the existence of extensive interfluvial uplands and the lack of a developed road system.
The Lower Rouge River watershed sustains the most pristine and diverse valley/tableland complex in Site District 7-4. Its 453 native species, and 225 introduced species represent an exceptional diversity for a suburban area in Southern Ontario (Varga, 1984 in Eagles & Beechey, 1985).