Invalid Unit Specified
M014 Acer saccharum - Betula alleghaniensis - Tsuga canadensis Forest Macrogroup

The U.S. National
Vegetation Classification
Type Concept Sentence: This macrogroup represents the mesic conifer - northern hardwoods of the eastern cool-temperate forests, ranging from the Upper Great Lakes region eastward to the Acadian region of southeastern Canada, to New York and Pennsylvania, and south along the Appalachians to northern North Carolina and eastern Tennessee; forests vary from pure hardwood dominance by Acer saccharum, Betula alleghaniensis, Fagus grandifolia, Quercus rubra, and Tilia americana to strong conifer dominance by Pinus strobus and Tsuga canadensis and (more eastward) Picea rubens.
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Common (Translated Scientific) Name: Sugar Maple - Yellow Birch - Eastern Hemlock Forest Macrogroup
Colloquial Name: Laurentian-Acadian Mesic Hardwood - Conifer Forest
Hierarchy Level: Macrogroup
Type Concept: These northern temperate conifer-hardwoods forests form the landscape matrix over much of the glaciated north temperate region of eastern North America, and at higher elevations along the Central and Southern Appalachians, becoming especially prominent in cooler settings. The forests are dominated by "northern hardwoods" (Acer saccharum, Betula alleghaniensis, and Tilia americana, and in parts of the range, Fagus grandifolia, Fraxinus americana, and Quercus rubra) and/or by Abies balsamea, Picea glauca, Picea rubens, Pinus strobus, or Tsuga canadensis. The canopy may be deciduous, coniferous, or mixed. These forests are found on mesic to dry sites in various landscape settings, usually not both dry and highly exposed. Climate is cool-temperate to subboreal. Soils are highly variable, from high-nutrient soils developed over limestone to acidic, nutrient-poor glacial outwash soils. Soil moisture regime is most often mesic. Spruce- or hemlock-dominated forests may occur on moist sites.
Diagnostic Characteristics: This macrogroup contains a combination of the moderately diagnostic northern hardwood - conifer species of Betula alleghaniensis, Tsuga canadensis, Pinus strobus, Picea rubens (eastward), and Thuja occidentalis, and more widespread northern hardwood species, such as Acer saccharum, Betula papyrifera, Fagus grandifolia, Fraxinus americana, Quercus rubra, and Tilia americana. Occasionally Picea glauca and Abies balsamea are present; the latter species is a frequent canopy component in eastern areas. Southward, in the Appalachian region, species such as Aesculus flava, Abies fraseri, Liriodendron tulipifera, and Quercus montana may occur. Shrub and herb species need to be added to this list of diagnostic taxa.
Rationale for Nominal Species or Physiognomic Features: These species are typical hardwood and conifer tree species.
Classification Comments: These forests are differentiated from other forest macrogroups in the range by the combination of northern hardwoods, white pine, spruce, fir, and/or hemlock, without significant presence of Quercus species other than Quercus rubra and without significant contribution of Carya species. Chapters in Barbour and Billings (2000) treat the red spruce - fir within the eastern deciduous forest region rather than boreal (following the treatment of Braun (1950)). Similarly, here we place all stands with Picea rubens with other cool-temperate types. We restrict the term "boreal" to forests that primarily or entirely lack temperate diagnostic species, which geographically corresponds largely to the North American forests within Bailey's (1997) subarctic "Tayga (boreal forest)" ecoregion. This macrogroup differs from Appalachian-Interior-Northeastern Mesic Forest Macrogroup (M883) by the lack of or low abundance of central mesophytic temperate forest taxa typical of Braun's (1950) Mixed Mesophytic region, such as Magnolia spp. and Carya [additional species needed here], and the presence or dominance of Pinus strobus, Tsuga canadensis, and Picea rubens. They differ from boreal forests in the absence or low abundance of boreal conifers (Abies balsamea, Picea glauca, Picea mariana, Pinus banksiana).

In Canada, consideration is being given as to whether northeastern mesic conifer (and mixedwood) forests will be separated from mesic northern hardwoods in the CNVC, and, if so, whether they should be differentiated at the macrogroup or submacrogroup level. If recognized, that conifer-mixedwood unit would define zonal vegetation in a low- to moderate-elevation region where the cool humid climate arises from prominent oceanic influences and abundant rainfall. One of the important things needing investigation is whether other humid northeastern temperate conifer/mixed forest (i.e., primarily Laurentian Subboreal Mesic Balsam Fir - Spruce - Hardwood Forest Group (G048)) would fall under this same macrogroup/submacrogroup (S. Basquill pers. comm. 2015).
Similar NVC Types:
M159 Laurentian-Acadian Pine - Hardwood Forest & Woodland, note:
M495 Eastern North American Boreal Forest, note: "is characterized by Abies balsamea, Picea glauca, Pinus banksiana, and Picea mariana, and absence of Picea rubens and absence or unimportance of northern hardwoods (e.g., Fagus grandifolia, Acer saccharum, Betula alleghaniensis)."
M882 Central Midwest Mesic Forest, note:
M883 Appalachian-Interior-Northeastern Mesic Forest, note:
Physiognomy and Structure: These are mostly closed-canopy, uneven-aged forests, but may have patchy openings due to gap dynamics, primarily from windthrow (Tyrrell and Crow 1994a, 1994b). Forests on rocky substrates, more extreme sites, may have open or stunted canopies. Stands range from strong dominance by conifers to strong dominance by hardwoods. Some stands have a supercanopy of Pinus strobus. Shrub, sapling and ground layers vary from open to dense, often influenced by the pit-and-mound topography resulting from windthrows. Moss cover is patchy to continuous.
Floristics: Dominant tree species include the typical conifers and hardwoods of Acer saccharum, Betula alleghaniensis, Fagus grandifolia, Fraxinus americana, Picea glauca, Picea rubens, Pinus strobus, Tilia americana, and Tsuga canadensis; Abies balsamea is occasional. Acer rubrum, Betula papyrifera, Populus grandidentata, and Populus tremuloides may be common. Other prominent canopy associates may include Prunus serotina, Thuja occidentalis, and Quercus rubra. Southward, in the Appalachians part of the range, Liriodendron tulipifera may also occur (Whittaker 1956). Abies balsamea and Picea glauca are uncommon associates. Canopy composition is dependent on a variety of factors, including geographic location, past disturbance, soils, slope, and aspect. Smaller trees that may form an understory include Ostrya virginiana, Sorbus americana, Acer spicatum, and Acer pensylvanicum. Prunus pensylvanica may also be common, especially in openings. The density and composition of shrub, herb, and bryophyte strata vary with geographic location and degree of past disturbance (i.e., canopy openings). Common shrub species include Corylus cornuta, Diervilla lonicera, Dirca palustris, Hamamelis virginiana, Lonicera canadensis, Prunus virginiana, and Viburnum lantanoides. A diverse set of characteristic herbaceous species include Actaea pachypoda, Actaea rubra, Allium tricoccum, Aralia nudicaulis, Arisaema triphyllum, Athyrium filix-femina, Clintonia borealis, Coptis trifolia, Cornus canadensis, Dryopteris campyloptera, Dryopteris carthusiana (= Dryopteris spinulosa), Gaultheria procumbens, Huperzia lucidula (= Lycopodium lucidulum), Lycopodium obscurum, Osmunda claytoniana, Oxalis montana, Maianthemum canadense, Medeola virginiana, Mitchella repens, Polygonatum pubescens, Polystichum acrostichoides, Streptopus lanceolatus (= Streptopus roseus), Trillium undulatum, Trientalis borealis, Uvularia sessilifolia, and, in areas with a limestone or other more calcareous substrate, Adiantum pedatum, Caulophyllum thalictroides, and Deparia acrostichoides (= Athyrium thelypterioides). The bryophyte layer is generally very well-developed, characterized by Bazzania trilobata, Pleurozium schreberi, Dicranum spp., and many others. These forests may also be invaded by non-native shrubs, including Berberis spp., Lonicera morrowii, Lonicera tatarica, Frangula alnus, Rhamnus cathartica, and others (Curtis 1959, Cohen et al. 2014).
Dynamics: The natural disturbance regime is characterized by frequent, small windthrow gaps, which allow for gap-phase regeneration of the shade-tolerant canopy dominants. Large-diameter coarse woody debris provides nurse logs for regenerating tree canopy species, and tip-up mounds for plant establishment and regeneration (Canham 1988, 1990). Catastrophic windthrow occurred infrequently (return intervals of >500 years) with several generations of trees passing between large-scale, severe disturbance events (Canham and Loucks 1984, Frelich and Lorimer 1991a, Frelich 2002). As a result, these mesic northern forests historically dominated vast areas of mesic uplands of the Great Lakes and were multi-generational, with old-growth conditions lasting many centuries (Cohen 2005).Fire is not an important factor, although it has been shown to occur at long return intervals (>500 years) in the presettlement landscape. Forests at higher elevations are affected by wind disturbance, debris avalanches, ice loading, and lightning fire, and can be susceptible to large blowdowns where the soils are shallow. Insect defoliation and selective herbivory by white-tailed deer can alter the composition and structure and favor browse-tolerant species. In the northern part of the range, the spruce budworm occurs in periodic outbreaks (~40-60 years) and causes significant defoliation and patchy blowdowns. Beech bark disease and emerald ash borer have locally killed canopy beech and American ash (Curtis 1959, Cohen et al. 2014).

Intensive and pervasive anthropogenic disturbance during the past 150 years has altered the extent, landscape pattern, natural processes, structure, and species composition of the mesic northern forest (Frelich 1995, Cohen 2005). In particular, old-growth and late-successional forests have been drastically reduced in acreage, or occur as remnant patches in a matrix of agricultural lands, early-successional forest, and young northern hardwoods (Leahy and Pregitzer 2003). Short-rotation timber management has replaced gap-phase dynamics as the dominant disturbance factor impacting structure and composition. Structural alterations include the reduction of large-diameter trees, snags, and coarse woody debris. Hemlock and white pine have declined in importance within these systems, and have been completely eliminated from many landscapes. Chronically high deer densities have limited tree recruitment and altered floral composition and structure (Frelich and Lorimer 1985, Alverson et al. 1988, Mladenoff and Stearns 1993, Alverson and Waller 1997, Rooney and Waller 2003, Cohen 2005).
Environmental Description: Climate: Climate is cool-temperate to sub-boreal. Soil/substrate/hydrology: The mesic northern forest is found chiefly on coarse-textured ground and end moraines, but also occurs commonly on silty/clayey lakeplains, thin glacial till over bedrock and medium-textured moraines. It also occurs locally on kettle-kame topography, moderately well-drained to well-drained sandy lakeplain and sand dunes. Sandy soils are especially common near the Great Lakes shorelines. Soils are highly variable, from high-nutrient soils developed over limestone to acidic, nutrient-poor glacial outwash soils. Soil moisture regime is most often mesic, but in the northern parts of this macrogroup's range, some pine-hardwood forests develop on more dry-mesic soils, while spruce- and hemlock-dominated stands may occur on somewhat poorly drained sites (Cohen et al. 2014). Southward, in the Appalachians region, this type is increasingly restricted to higher elevations, typically above 1230 m (4000 feet) (Whittaker 1956).
Geographic Range: This macrogroup is found across the north temperate region of eastern North America from Minnesota and the Great Lakes east across to the Acadian region of southern Canada to the Atlantic Provinces and south at increasingly high elevations in the red spruce-fir zones of the Southern Appalachians to North Carolina and eastern Tennessee.
Nations: CA, US
States/Provinces: CT, DE, MA, MD, ME, MI, MN, NB, NC, NH, NS, NY, ON, PA, QC, RI, VA, VT, WI, WV
US Forest Service Ecoregions (2007)
Domain Name:
Division Name:
Province Name: Northeastern Mixed Forest Province
Province Code: 211    Occurrence Status: Confident or certain
Section Name: White Mountains Section
Section Code: M211A     Occurrence Status: Confident or certain
Omernik Ecoregions:
Plot Analysis Summary:
Confidence Level: High
Confidence Level Comments:
Grank: GNR
Concept Lineage:
Obsolete Names:
Obsolete Parents:
Synonomy: > Balsam Fir: 5 (Eyre 1980)
> Dry-mesic northern hardwoods (Curtis 1959)
> Fir-Birch (Heinselman 1996)
< Hemlock - White Pine - Northern Hardwoods Region (Braun 1950) [While a forest region is not equivalent to a forest group, the characterization of the major types in this region fits the group (G743) concept. Also see Nichols (1935) for an earlier treatment on which Braun based some of her descriptions.]
> Hemlock - white pine - northern hardwoods forests (Delcourt and Delcourt 2000) [in Barbour and Billings (2000).]
> Mesic Northern Hardwoods (Curtis 1959)
> Northern forest - mesic (Curtis 1959)
> Northern hardwood forest (Flaccus 1972)
> Northern hardwoods (Küchler 1964)
> Northern hardwoods - fir forest (Küchler 1964)
> Northern hardwoods - spruce forest (Küchler 1964)
< Red Spruce - Fir Forest Group (Faber-Langendoen and Menard 2006)
> Spruce - fir forests (Delcourt and Delcourt 2000) [in Barbour and Billings (2000).]
> Spruce-Fir Forest (Davis 1966)
< Spruce-Fir-Cedar Forest (Albert and Comer 2008)
? Zone 2: Northern hardwood - hemlock - white pine (Westveld 1956)
? Zone :1 Spruce - fir - northern hardwoods (Westveld 1956)
Concept Author(s): G.E. Nichols (1935); H.J. Oosting and W.D. Billings (1951)
Author of Description: S. Gawler, M. Pyne, S. Menard, L.A. Sneddon and D. Faber-Langendoen.
Acknowledgements: Josh Cohen provided many edits and made available text from his and other Michigan staff publications.
Version Date: 21May2015
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