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Promoting Wildlife Diversity in Your Woodlot

by Lynn J. Landriault

Historically, southern Ontario was covered by forests interspersed with lakes, wetlands, grasslands, and other open areas. The natural landscape has changed dramatically as a result of agricultural practices and urban development. In many areas, private woodlots are the only remaining forests, and are critical for maintaining tree diversity and providing habitat for wildlife that require forest cover. Thoughtful, well-informed management approaches can result in woodlots that provide habitat for a wide range of forest-dependent wildlife species, while providing owners with a host of other benefits, including economic benefits in the form of wood products.

The following are some steps that owners can take to help improve and maintain wildlife habitat in their woodlots.

Good silviculture

Develop long-term goals for your woodlot. These might include a sustainable commercial hardwood harvest, a small annual harvest for firewood, or harvesting to accelerate the rate of succession of abandoned pastureland to forest. Apply the appropriate silvicultural methods for the tree species and condition of your woodlot and the goals you want to achieve. This approach should yield a diversity of healthy forest communities across the landscape. Many of our silvicultural approaches are based on natural disturbance processes.

For example, selection silviculture (single-tree and group selection) mimics individual and group tree mortality due to windthrow, ice, insects, diseases, and old age, whereas shelterwood silviculture mimics moderate-intensity understorey fires. Native wildlife has adapted to natural disturbances, so applying these techniques should ensure that suitable habitat is available for most species. Whenever possible, enlist the aid of a professional forester to help develop good-quality harvesting prescriptions, and use certified tree markers to ensure the prescriptions are properly applied. Discuss with loggers the need to work carefully around residual trees to reduce logging damage.

Tree species diversity

Keep uncommon tree species to increase diversity in your woodlot and assist in maintaining genetic diversity across the landscape. Some trees are uncommon because they are near the limit of their geographical range. Such trees may have genetic adaptations different from those in the main species range, so they should be retained to maintain genetic variability. Other tree species may be uncommon in the local landscape as a result of existing soil types and moisture levels or past harvesting practices. The retention of uncommon trees may provide wildlife habitat not provided by common trees. For example, woodpeckers rarely excavate cavities in conifers. So the presence of a few hardwood trees in white and red pine stands can significantly increase the number of cavity trees and the wildlife species that use them.

Mast trees

Mast trees are trees that produce nuts and berries. The production of mast, such as acorns and beech nuts, has a huge effect on the abundance of many wildlife populations including small mammals, grouse, deer and bears. Plan to keep a minimum of 10 mast trees/ha in your woodlot. These trees should be large (25+ cm diameter), dominant trees, with healthy crowns. Keep mast trees in the following order of preference: oak, beech, cherry, hickory, basswood, butternut, walnut and ironwood. Note that butternut is listed as an endangered species under Ontario’s Endangered Species Act, and cannot be harvested without satisfying the requirements outlined in the Regulations.

Conifers in hardwood stands

In the past, southern Ontario hardwood stands contained higher densities of conifers than we observe today. The dense year-round canopy of mature conifers provides wildlife with shelter from poor weather, places to hide from predators, seeds and foliage to feed on, nesting or resting sites, and a significantly reduced snow depth under their canopy. Plan to keep a minimum of 10 conifer trees/ha in your woodlot, some of which you may want to keep in clumps, as this would increase their positive thermal and snowpack effects in winter. These trees should be large (25+ cm diameter) and healthy. Keep conifer trees in the following order of preference: hemlock, red spruce, white pine, white cedar, white spruce and balsam fir.

Supercanopy trees

Supercanopy trees reach above the forest canopy; they have survived past disturbances and hence are taller and older than the trees in the surrounding area. Supercanopy trees are often large conifers, such as white pine, but may also be large oaks or aspen. These trees provide structural diversity and are excellent landmarks for birds. They often serve as perching, roosting (i.e., resting), or nesting sites for raptors, including hawks and bald eagles. Supercanopy white pines are preferred refuge trees for mother black bears with cubs, and bears often bed down at the base of these trees. Endeavour to keep at least one supercanopy tree/4 ha. These trees should be large (60+ cm in diameter) and higher than surrounding trees.

Cavity trees

squirrels in a holeBaby squirrels in the cavity of a tree.Cavity trees are trees that have one or more holes in the trunk or main branches. Some cavities are excavated by birds, whereas others are created by decay associated with wounding or branch mortality. A large variety of wildlife makes or uses tree cavities at some stage in their lives. Woodpeckers excavate cavities, which they use for nesting, roosting and feeding. Many birds will nest or roost in existing cavities, including saw-whet owls, barred owls, screech owls, and kestrels, as well as several species of waterfowl (e.g., hooded mergansers and wood ducks). Various mammals also rely on existing cavities for denning, resting, and escaping predators. These include mice, flying squirrels, fishers, racoons, porcupines and weasels. Good-quality cavity trees are large living trees with a cavity that was excavated by a woodpecker for nesting or roosting. The entrance is typically circular, with clean edges and surfaces. The hole may appear dark because it leads to a hollow chamber. Trees with large, natural cavities are also considered good-quality cavity trees. Plan to keep a minimum of 10 living cavity trees/ha in your woodlot. These trees should all be a minimum of 25 cm in diameter; bigger is better. Although some woodpeckers do prefer to excavate nesting cavities in dead trees, these trees should only be retained if they do not pose a safety concern.

Downed wood

Downed wood is the term used to describe trees or branches that have fallen to the forest floor. Downed wood is a critical component of a healthy forest ecosystem. It stabilizes soil, retains moisture, and allows for the recycling of nutrients. Large downed trees are used as drumming sites by ruffed grouse and plucking perches by raptors, while a wide variety of wildlife use downed trees as nesting, denning and overwintering sites. Salamanders can often be found under downed wood during the day, and the cavities in downed wood provide egg-laying sites for red-back salamanders. Small mammals use hollow downed trees and edges of downed trees as travel corridors, which in turn results in their use by predators such as weasels. Huge, diverse communities of fungi, bacteria, and beetles and other insects require downed wood to exist. Leaving downed wood on the forest floor is a key step in maintaining the ecological integrity of a woodlot.

Stick nests

stick nestStick nestStick nests are large nests built by raptors and other large birds such as ravens and herons. As in the case of tree cavities, there is a suite of wildlife species that use stick nests but do not build their own. These include merlins and many of our forest-nesting owls (great-horned, long-eared, barred). Larger nests (built by larger birds) are more likely to be reused by the original birds or by others. For this reason, a minimum of 20 m of forest cover should be retained around larger nests (those about the size of a pickup truck tire and larger) to protect the tree and maintain some canopy closure around it. Local or regional Ontario Ministry of Natural Resources biologists can provide helpful direction for harvesting prescriptions near nests of species more sensitive to habitat change, such as northern goshawks, red-shouldered hawks, ospreys, bald eagles and herons. The publication Forest raptors and their nests in central Ontario is a helpful tool for identifying stick nests by species:

Woodland pools

Woodland pools are temporary bodies of water that are not connected to streams or wetlands. They may hold water for only a few months each year or may be wet throughout the year except during years of drought. Generally, woodland pools do not contain fish, which makes them unique aquatic habitats for a wide range of vertebrates and invertebrates. Some species of wildlife only breed in woodland pools, including wood frogs, fairy shrimp, and spotted, blue-spotted and Jefferson salamanders. Many other species of frogs, salamanders, and invertebrates can be found in woodland pools. When operating near woodlands pools, the goal is to ensure that there are no changes to the longevity, water temperature, or water quality of the pools. To accomplish this goal, maintain a dense forest canopy around woodland pools and avoid any soil disturbance within 15 m.

For details regarding forest management guidelines with respect to wildlife habitat on Crown land in Ontario, please refer to the Forest Management Guide for Conserving Biodiversity at the Stand and Site Scales (Stand and Site Guide).

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