Natural Communities of NH -- Photo Guide

Rich mesic forest  (S3)

Rich organic matter and sediments often accumulate on or below steep slopes, such as on talus slopes, in ravines, in drainages, and below cliffs. The forests found in these locations are referred to as rich or semi-rich. Frequently shared tree canopy species in such forest types include sugar maple (Acer saccharum) and white ash (Fraxinus americana). Rich and semi-rich forests often intergrade with one another or are found as small patches within related community types such as northern hardwood forests, talus slope forests, seepage forests, and forest seeps.

Rich mesic forests are enriched hardwood forests growing on soils with relatively high levels of moisture, mineral nutrients, and high-quality organic matter. These forests grow at a faster rate than other forest types and may have about twice as many species of herbs and shrubs. The dominant tree is usually sugar maple, often accompanied by white ash and basswood (Tilia americana). Herbaceous species in the understory include many spring ephemerals that complete their life cycles early in the spring before the trees have finished leafing out. Some herbaceous species are restricted to very rich conditions, such as maidenhair fern (Adiantum pedatum) and blue cohosh (Caulophyllum thalictroides). Among the many rare plant species sometimes found in this community type are ginseng (Panax quinquefolius), Goldie's fern (Dryopteris goldiana), sweet cicely (Osmorhiza berteroi), and squirrel corn (Dicentra canadensis).

Rich forests are especially vulnerable to nutrient and species loss when they are disturbed. Some examples of semi-rich mesic sugar maple forests may actually be disturbed examples of former rich mesic forests. Both types are quite uncommon in New Hampshire, and undisturbed examples are rare. Together they harbor many of the state’s rare forest plant species. These natural communities may also be found where mineral-rich bedrock and ample moisture enrich the soil, regardless of the slope or topography. “Sugarbushes” are usually associated with either of these two communities. Known examples in New Hampshire are all found below 2600 feet in elevation.

Characteristic vegetation:
ugar maple (Acer saccharum) is the primary dominant, with white ash (Fraxinus americana) and basswood (Tilia americana) as frequent associates. American beech (Fagus grandifolia) and yellow birch (Betula alleghaniensis) are often present, but less frequent. Ironwood (Ostrya virginiana) is occasional and butternut (Juglans cinerea) is infrequent in lower elevation examples (<1,500 ft.).

Any or all species listed for semi-rich mesic sugar maple forest may be present, although rich mesic forests typically have a broader compliment of enriched-site indicator species that are restricted to the richest end of the nutrient gradient. Many of these species are “vernal herbs,” which flower and fruit early in the season before tree canopies have fully emerged.

Most rich mesic forests are indicated by any combination of at least several of the following species that can be used to distinguish this community from essentially all others in New Hampshire: Adiantum pedatum (northern maidenhair fern), Caulophyllum thalictroides (blue cohosh), Deparia acrostichoides (silvery spleenwort), Botrychium virginianum (rattlesnake-fern), Dryopteris goldiana (Goldie’s fern), Dicentra canadensis (squirrel-corn), D. cucullaria (Dutchman’s breeches), Asarum canadense (wild ginger), Carex platyphylla (flat-leaved sedge), C. plantaginea (plantain-leaved sedge), Eupatorium rugosum (white snakeroot), Oryzopsis racemosa (blackseed rice-grass), Rubus odoratus (purple-flowering raspberry), Sanguinaria canadensis (bloodroot), Cypripedium pubescens (large yellow lady’s-slipper), Viola canadensis (Canada violet), V. pubescens (downy yellow violet), and Aralia racemosa (spikenard). Potential rare species in northern examples may include Pyrola asarifolia (pink wintergreen), Osmorhiza chilensis (mountain sweet-cicely), Carex albursina (Sheldon’s sedge), Solidago calcicola (rock goldenrod), Carex aestivalis (summer sedge), and Trillium grandiflorum (large-flowered trillium). Numerous forest-sedges are restricted to rich forests, particularly the “wide-leaved” sedges (Laxiflorae and Careyanae groups). Sedges include flat-leaved sedge, plantain-leaved sedge, Carex leptonervia (faint-nerved sedge), C. laxiflora (lax sedge), C. blanda (bland sedge), C. sprengelii (long-beaked sedge), C. hirtifolia (hairy-leaved sedge), C. pedunculata (peduncled sedge), and C. rosea (star sedge). There are numerous other herbs that occur in this community that are not listed here, including those found in more nutrient-poor hardwood forests (see sugar maple - beech - yellow birch forest list).

Occurrences in the Connecticut River valley have the potential to contain certain species absent from the remainder of the state, including showy orchis (Galearis spectabilis), northern waterleaf (Hydrophyllum virginianum), and bladdernut (Staphylea trifolia).

Two variants are described: 

   1.  Typic variant: This variant is found at low to mid elevations from ~500–1,800+ ft. (as described above). With additional documentation, rich river terraces in northern New Hampshire may warrant distinction at the variant level as with semi-rich mesic sugar maple forest

   2.  High elevation/near-boreal variant: The variant is found at elevations ranging from 1,800–2,600 ft. High percent cover in the herb layer is typical, particularly of ferns. Many known examples have light woody understories. Tall canopies are occasional but generally decrease in height and cover with increasing elevation. Species usually present in higher frequency and abundance than in lower enriched forests include shining clubmoss (Huperzia lucidula), inflated sedge (Carex intumescens), bluebead lily (Clintonia borealis), rosey twisted stalk (Streptopus roseus), mountain wood fern (Dryopteris campyloptera), and drooping woodreed (Cinna latifolia). Ferns include silvery spleenwort, lady fern (Athyrium filix-femina), ostrich fern (Matteuccia struthiopteris), intermediate wood fern (Dryopteris intermedia), and Braun’s holly fern (Polystichum braunii). Other enriched site species include millet-grass (Milium effusum), wood nettle (Laportea canadensis), and wild leek (Allium tricoccum). Mountain sweet-cicely (Osmorhiza chilensis) and rock goldenrod (Solidago calcicola) may occur in this variant. Ash, ironwood, basswood, and numerous understory species present at lower elevations are absent, although an enriched character is still evident.

Classification confidence: 1

Distribution: Found throughout the state on low to mid elevation till landscapes and potentially on steep river terrace slopes of certain valley bottom atelevations from <500–2,600 ft. Most frequent in the Connecticut River, Vermont Uplands, Mahoosuc-Rangeley Lakes, Connecticut Lakes, and the north and west sides of the White Mountain subsections, and locally elsewhere. High elevation variant examples occur from approximately 1,800–2,600 ft. elevation, but mostly above 2,000 ft.

Good examples
of rich mesic forest communities can be seen at the Society for the Protection of NH Forests' Yatsevitch Forest (Plainfield), Velvet Rocks ravine (Hanover), Ore Hill (Warren), Sugarloaf Mtn. (Benton), Cape Horn State Forest (Northumberland), Cornish Town Forest (Cornish), off-trail at CT River State Forest (Charlestown), and off-trail at Weeks State Park (Lancaster).

This community often occurs as patches within a larger rich mesic forest system, and sometimes as part of rich north-temperate talus/rocky woods systems.

click here for photos of characteristic plants of rich mesic forests

rich mesic forest (photo by Dan Sperduto)
rich mesic forest
(photo by Dan Sperduto)

Maidenhair fern is one of the signature species of rich mesic forest in NH, as seen here at CT River State Forest (photo by Ben Kimball for the NH Natural Heritage Bureau)
Maidenhair fern is one of the signature species of rich mesic forest in NH,
as seen here at CT River State Forest (photo by Ben Kimball)

Baneberry and Christmas fern are 2 other indicator species of rich mesic forests, seen here at Cape Horn State Forest (photo by Ben Kimball for the NH Natural Heritage Bureau)
Baneberry and Christmas fern are 2 other indicator species of rich mesic forests,
seen here at Cape Horn State Forest (photo by Ben Kimball)

Wide-leaved sedges are indicative of rich mesic forests (photo by Doug Bechtel)
Wide-leaved sedges are indicative of rich mesic forests (photo by Doug Bechtel)

Rich mesic forest in Stewartstown (photo by Doug Bechtel for the NH Natural Heritage Bureau)
Rich mesic forest in Stewartstown (photo by Doug Bechtel)

rich mesic forest (photo by Dan Sperduto)  rich mesic forest (photo by Dan Sperduto)
rich mesic forest in the CT River Valley (photos by Dan Sperduto)

Please see also our fact sheet for rich and semi-rich mesic forests in NH.

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