Forests and Barrens in the Highlands Corridor
The Highlands Corridor is dominated by mature forests with a higher component of deciduous forest than identified at the Ecodistrict Level. Stands of old growth forest are present, the largest of which is the Catchacoma Old-growth Forest.
Based on an analysis of Forest Resource Inventory data (Ontario Ministry of Natural Resources and Forestry, 2020) and HHLT wetland mapping (Glenside Ecological Services Limited, 2020), the Highlands Corridor is 71% forested of which 51% is mixedwood, 35% is deciduous and 14% is coniferous (See Figure 5). The dominant ecosites consist of maple forests (Ecosite G059); mixedwood forests of maple, American beech, American basswood, red oak, ironwood, eastern hemlock and yellow birch (Ecosites G058, G059 and G076); and pine forests (Ecosites G048 and G054). This representation differs from the Ecodistrict (5E-11) which has a higher representation of coniferous forests (25%) and lower representation of deciduous forest (14%) (Wester, Henson, Crins, Uhlig, & Gray, 2018).
Based on the age of the overstory and respective ecosite (Chambers, Naylor, Nieppola, Merchant, & Uhlig, 1997), the forest stand was classified into five distinct age classes: pre-sapling, sapling, immature, mature or old growth. The age ranges associated with each development stage varies among ecosites (Holloway, Naylor, & Watt, 2004). Through this analysis it was determined that 75% of the forests of the Highlands Corridor are mature, 21% are immature and another 2% are sapling or pre-sapling. Old growth forests represent 2% of the forested cover in the Highlands Corridor.
The largest identified stand of old growth forest (210 ha) is located immediately to the west of Kawartha Highlands Provincial Park and north of Catchacoma Lake (See Figure 6). This area, known as the Catchacoma Old-growth Forest, has been subjected to preliminary field investigations that suggest the old growth stand could be as large as 662 ha and represent the largest old growth stand of Eastern Hemlock in Ontario (Quinby P., 2019; Quinby P., 2020). Organizations such as the Wilderness Committee are currently advocating for the protection of the Catchacoma Old-growth Forest (Wilderness Committee, 2021).
Metamorphic rock barrens have a limited occurrence in southern Ontario and deserve a relatively high priority for protection. Metamorphic rock barrens are a significant component of the Highlands Corridor.
Metamorphic rock barrens represent 1.2% of the landcover with higher representation north of Irondale around the Milburn area, and immediately north of Kawartha Highlands Provincial Park. Rocky barrens are limited in Central Ontario to the southern edge of the Canadian Shield and this unique feature adds to a mosaic of habitats that supports high biodiversity in the Highlands Corridor. Since the shield is impervious the extremes of wetness and dryness are greater than those on nearby alvars, where the rock is porous (Catling & Brownell, 1999). Metamorphic rock barrens generally have an acid soil reaction and a unique floral and faunal community including many provincially significant plant and animal species (Catling & Brownell, 1999).