Forest types are distinctive associations of trees, shrubs and herbaceous plants. They are named for the predominant tree species.
There are other ways to group and describe forests. Natural communities and wildlife habitat are commonly used. Natural communities describe current and potential vegetation in the absence of disturbance. A comparison of these three methods is in the New Hampshire Wildlife Action Plan (Appendix C of the plan).
Forest types describe large expanses of land, or site-specific forest stands (grouping of trees similar in species, age and site). The common forest types in New Hampshire are white pine, northern hardwood, spruce-fir, red oak, hemlock, and aspen-birch.
Climate, elevation, soil conditions, and land use history all play a role in determining which forest type is growing in a particular area. Forest type, in turn, influences the variety of wildlife inhabiting an area and the silvicultural options available.
A forest type may be dominated by a single tree species or by several species growing together. White pine often occurs in a single-species stand. Northern hardwood, composed of sugar maple, beech, yellow birch and smaller amounts of other species, is a multiple-species type. Two types can blend together to form a mixed-wood type. Mixed-wood stands often occur in transition zones between major types. Two common mixed types are the pine-oak and spruce-fir-northern hardwood combinations.
This type is most common in southern New Hampshire. White pine occurs in pure stands or mixed with red pine, hemlock, red oak or other hardwoods.
White pine often colonizes abandoned agricultural land. On fertile sites it is gradually replaced by hardwood or hemlock through succession. On less fertile, sandy soils the type is more persistent.
On sandy soils, acid-loving plants such as blueberries, starflowers, and pink lady's slippers are common. Associated wildlife include red squirrel, deer mouse, pine warbler, and red-breasted nuthatch. Owls often use white pine for winter roosting.
Most common in central and northern New Hampshire, northern hardwood is usually a mix of sugar maple, beech, yellow birch, red maple, and white ash. Sugar maple is typically the most abundant species on sites with fertile soils. Beech increases in abundance on drier sites and yellow birch becomes more prominent on moist sites.
Northern hardwood tends to be a relatively stable and permanent forest type. Stands typically grow on the slopes of hills and mountains, where the soils are fertile and well-drained. Sugar maple and beech are shade-tolerant trees that can reproduce and grow in the shade of a forest canopy. Yellow birch and white ash are less tolerant of shade and require more sunlight to reproduce and grow.
Common understory trees and shrubs include striped maple, witch hazel, and hobblebush. Associated wildlife include gray fox, flying squirrel, red-eyed vireo, white-breasted nuthatch, and ovenbird.
Most common in the north, red spruce and balsam fir dominate this type, which grows on poorly drained flats and the shallow, rocky soils of mountaintops.
Because of where they grow, these trees are susceptible to windthrow. The spruce budworm is a native insect which can impact vast areas during periodic outbreaks. Heart-rot fungi can affect overmature balsam fir.
Bunchberry, goldthread, and trilliums are common wildflowers and associated wildlife include pine marten, snowshoe hare, spruce grouse, gray jay, black-backed woodpecker, and ruby-crowned kinglet. Deer often use spruce-fir stands for winter cover.
The red oak type occurs in close association with white pine in southern New Hampshire. Stands of nearly pure red oak are common on ridge tops. On abandoned agricultural land, red oak mixes with white pine to form the pine-oak type. Red maple and black birch are common associates. Maple-leaved viburnum, bracken fern, and whorled loosestrife are common understory species.
Deer, turkey, gray squirrel, and many other species eat acorns. Blue jays, tufted titmice, scarlet tanagers, and eastern towhees are some of the birds that commonly nest in red oak and pine-oak stands.
Hemlock occurs on wet flats, rocky ridge tops, and moist slopes in southern and central New Hampshire. Its ecological characteristics are similar to the spruce-fir type of the north.
Striped wintergreen and downy rattle-snake plantain sometimes grow under dense hemlock. Hobblebush and maple-leaved viburnum may grow in small canopy openings. Red-breasted nuthatches, solitary vireos, black-throated green warblers, and hermit thrushes are typical breeding birds. Deer often use hemlock stands for winter cover.
Aspen-birch is a pioneer type relatively uncommon in the state. The type is composed primarily of quaking and big-toothed aspen and white birch and occurs on a wide variety of soils.
Aspen and white birch require full sunlight to grow. Disturbances such as fire, windstorms, or clearcutting create the conditions necessary for reproduction. In the absence of disturbance, natural succession leads to aspen-birch stands being replaced by other types.
Common associates in young stands are raspberries and blackberries. Aspen-birch provides valuable habitat for ruffed grouse, woodcock, Nashville warbler, mourning warbler, and beaver.
Manage a diverse forest to meet landowner objectives and for the environmental, economic and social well-being of the state.
2.2 Forest Structure; 2.3 Regeneration Methods; 2.4 Managing for High-Value Trees; 5.1 Insects and Diseases; 6.7 Aspen Management; 7.1 Natural Communities and Protected Plants.
New Hampshire Fish and Game. New Hampshire Wildlife Action Plan appendix C: Comparison between forest types, natural communities and wildlife habitat. 2005. http://www.wildlife.state.nh.us/Wildlife/Wildlife_Plan/WAP_pieces/WAP_App_C_Nat_Comm_Crosswalk.pdf Accessed March 5, 2010.