Sugar maple - beech - yellow birch forest (S5)
Sugar maple - beech - yellow birch forest is the most common hardwood forest type in northern New Hampshire, and is frequently referred to simply as northern hardwood forest. It is most abundant on mid to upper mountain slopes between 1,500 and 2,500 feet elevation, with patchier distribution at lower elevations. It is transitional to high-elevation spruce - fir forests at higher elevations and lowland spruce - fir forests, hemlock - spruce - northern hardwood forests, or hemlock - beech - oak - pine forests at lower elevations. Small windthrow gaps of one to many trees are the primary disturbance in these forests. Yellow birch is successful in establishing itself in these gaps, and although it is not as shade tolerant as beech and sugar maple, it is long-lived and consequently an important late-successional dominant (approximately 200–380 years).
Rapid and high-density growth of pin cherry (Prunus pensylvanica) can occur from buried seeds in clearcut and other large-gap disturbance patches. Pin cherry is an important nutrient-sink on these sites, effectively retaining nutrients and organic matter within the system.
Soils are moderately well drained fine sandy loams. Soils form from till derived from granitic igneous rocks and metamorphic rocks such as schist and gneiss, yielding soils with relatively low mineral nutrient content. Soils tend to be drier than in rich mesic forests and high-elevation spruce - fir forests, but more mesic than at sites with increased beech cover.
Characteristic vegetation: Sugar maple (Acer saccharum) and beech (Fagus grandifolia) are the primary late successional dominants, with yellow birch (Betula alleghaniensis) (a long-lived gap colonizer) next in abundance. Other common or occasional hardwood trees include paper birch (Betula papyrifera), striped maple (Acer pensylvanicum), mountain maple (Acer spicatum), and white ash (Fraxinus americana). Spruce and fir are absent or sparse.
Hobblebush (Viburnum alnifolium) is common in the shrub layer, while intermediate wood fern (Dryopteris intermedia) is frequent and often abundant in the herbaceous layer. Shining clubmoss (Huperzia lucidula), blue-bead lily (Clintonia borealis), and Canada mayflower (Maianthemum canadense) are also common in the understory. Other characteristic species that may be present include Canada mayflower (Maianthemum canadense), northern wood sorrel (Oxalis montana), starflower (Trientalis borealis), whorled aster (Oclemena acuminata), and sessile-leaved bellwort (Uvularia sessilifolia).
Small windthrow gaps are the primary disturbance agents in these forests. When larger blowdowns occur, or following a clearcut, pin cherry (Prunus pensylvanica) can grow rapidly and in high densities, making it an important nutrient sink at those sites.
Species that are less frequent here and more typical in either higher elevation spruce - fir or lower elevation hemlock and/or hardwood forests include partridgeberry (Mitchella repens), bunchberry (Cornus canadensis), goldthread (Coptis trifolia), Indian pipes (Monotropa uniflora), pink lady’s-slipper (Cypripedium acaule), and wintergreen (Gaultheria procumbens).
Variants: Two variants are described:
1. Typic variant
(as described above)
2. High-elevation fern glade variant
1,900 ft. - 2,600 ft.; increased productivity and cover or herbs; may form a "fern glade" appearance. intermediate wood fern (Dryopteris intermedia) and mountain wood fern (Dryopteris campyloptera) are often the most abundant species. Some combination of increased light reaching the understory, increased browse of woody regeneration, and/or increased moisture interception at higher elevations probably contributes to the increased productivity and cover of herbs in this variant.
Good examples of this community can be seen at Mountain Pond (Chatham), The Bowl Research Natural Area (
Sugar maple - beech - yellow birch forest often occurs as part of a larger northern hardwood conifer forest system.
Sugar maple - beech - yellow birch forest near The Flume (photo by Ben Kimball)
sugar maple - beech - yellow birch forest at Nancy Brook (photo by Ben Kimball)
the floor of a sugar maple - beech - yellow birch forest in Shelburne (photo by Ben Kimball)