Three silviculture systems are used in the Sudbury Forest. The apllication of each system depends on the light requirements for successful regeneration of different species groupings.
The clearcut silvicultural system is used for stands of shade-intolerant trees. In clearcutting, all or most of the trees are removed in one cut. The size, shape and pattern of the cuts on the overall landscape emulate the effects of large, natural disturbances such as fire. Residual features, such as internal patches, individual trees, snags and downed woody debris, mimic the stand level structural diversity of areas disturbed by fire. The cut areas may be replanted, or left to naturally regenerate with shade-intolerant species. Although the individual stands of trees are even-aged, all ages may be represented on the landscape at any one time.
Shade-intolerant species of trees are those that require full sunlight to thrive. They are sometimes called pioneer species because they are the first to become established on large, open, disturbed sites. They include poplar, white birch, jack pine and red pine. Stands of these trees tend to be "even-aged" (all the trees are about the same age), reflecting the fact that all the trees became established at the same time, usually after a major disturbance such as fire.
The Shelterwood system is used with mid-tolerant species. It involves the complete removal of a stand in a series of cuts, while a new stand develops in the partially shaded understory. It mimics major, natural disturbances such as wind, fire and insects, that leave large gaps in the forest canopy where mid-tolerant species can thrive. It produces an even-aged stand of trees.
Mid-tolerant trees are those that can tolerate partial shade as saplings, but also require some sunlight in order to thrive. They include tree species such as oak, ash, hemlock, and white pine. Forest stands that are dominated by mid-tolerant species tend to be even-aged - that is, most of the trees are the same age.
Selection cutting is used for the majority of shade-tolerant hardwood forests. About every 20 to 30 years, individual mature and declining (diseased or unhealthy) trees are cut. The growth rate and quality of the remaining trees improves, and young trees of the shade-tolerant species become established in the mostly-shaded understory. Selection cutting imitates minor natural disturbances like wind and disease, and perpetuates an all-aged tolerant hardwood forest.