Natural Community Systems -- Photo Guide

Rich mesic forest system

rich mesic forest system at Cape Horn State Forest (photo by Ben Kimball for the NH Natural Heritage Bureau)
rich mesic forest system at Cape Horn State Forest (photo by Ben Kimball)


DescriptionRich mesic forest systems are relatively small but unique forest areas that, despite some minor herbaceous variation, exhibit a remarkably consistent composition from northern to southern New Hampshire.  This is in contrast to the matrix forest types surrounding the rich mesic forests, which range from northern hardwood (-conifer) forests in northern New Hampshire, to hemlock - hardwood - pine or Appalachian oak - pine forest systems further south.  In all cases, this forest system is marked by the dominance of sugar maple and a host of rich-site indicator species largely restricted to enriched hardwood forests.  Fagus grandifolia (American beech) and Betula alleghaniensis (yellow birch) are more abundant in semi-rich areas and less frequent in rich mesic forests.  While rocky areas can be present, this system contrasts with rich north-temperate talus/rocky woods and rich Appalachian oak rocky woods systems by the absence of extensive talus or loose rocky slopes with herbs and species preferential to dry-mesic rocky sites.  They are most common and largest in areas with relatively calcium-rich bedrock and in association with slope-bases and coves, and on river terrace escarpments along the Connecticut and Merrimack Rivers.  This system more often than not has a mix of rich mesic forest and semi-rich mesic sugar maple forest communities.  On river terrace slopes and adjacent terrace flats, rich mesic forest systems can include the [former] rich sugar maple - oak - hickory forest community.

Rich mesic forests are characterized by a large number of rich and semi-rich site indicator plants, many of which are “vernal herbs” that flower and fruit early in the season before tree canopies have fully emerged.  There are numerous other herbs that occur in rich mesic forests not listed below, including those found in more nutrient-poor matrix forests of the region.

Diagnostic natural communities:
   • Rich mesic forest (S3)
   • Semi-rich mesic sugar maple forest (S3S4) 

Peripheral or occasional natural communities:
   • Semi-rich oak - sugar maple forest (S2S3)

Landscape settings: concave to neutral hillside slope positions, particularly in regions of calcium-rich bedrock and in topographic positions influenced by colluviation (e.g., slope-bases, below cliffs, and in coves and drainages)

Soils: variable: mesic to wet-mesic; well to moderately well drained; deep to shallow; loams, silt loams, and fine sandy loams with variable gravel and stone content; often with a well-mixed “mull” A horizon

Spatial pattern: variable (<1–20+ acres), although often elliptical or broad-linear when controlled by topographic features (i.e., slope-bases, coves, and drainages)

Physiognomy: forest

Distribution: throughout the state; more common in regions dominated by calcium-rich bedrock

Characteristic species:

Semi-rich mesic sugar maple forest:
Trees and shrubs
      Acer saccharum (sugar maple)
      Fraxinus americana (white ash)
      Tilia americana (basswood)
      Ostrya virginiana (ironwood)
      Cornus alternifolia (alternate-leaved dogwood)
      Sambucus racemosa (red elderberry)

      Arisaema triphyllum (Jack-in-the-pulpit)
      Viola rotundifolia (round-leaved violet)
      Actaea spp. (baneberries)
      Tiarella cordifolia (foamflower)
      Solidago flexicaulis (zigzag goldenrod)
      Botrychium virginianum (rattlesnake-fern)
      Deparia acrostichoides (silvery spleenwort)
      Milium effusum (millet-grass)
      Osmorhiza claytonii (Clayton’s sweet-cicely)
      Panax quinquefolius (ginseng)
      Polystichum acrostichoides (Christmas fern)

Rich mesic forest:
Above species plus at least several of the following species: 
      Adiantum pedatum (northern maidenhair fern)
      Caulophyllum thalictroides (blue cohosh)
      Dryopteris goldiana (Goldie’s fern)
      Dicentra canadensis (squirrel-corn)
      Dicentra cucullaria (Dutchman’s breeches)
      Asarum canadense (wild ginger)
      Carex platyphylla (flat-leaved sedge)
      Carex plantaginea (plantain-leaved sedge)
      Eupatorium rugosum (white snakeroot)
      Sanguinaria canadensis (bloodroot)
      Cypripedium pubescens (large yellow lady’s-slipper)
      Viola canadensis (Canada violet)
      Viola pubescens (downy yellow violet)
      Aralia racemosa (spikenard)
      Pyrola asarifolia (pink wintergreen)
      Osmorhiza chilensis (mountain sweet-cicely)
      Solidago calcicola (rock goldenrod)
      Carex aestivalis (summer sedge)
      Galearis spectabilis (showy orchis)

Associated natural community systems Rich mesic forest systems are found as small to large patches in northern hardwood – conifer forest, hemlock – hardwood – pine forest, and (less frequently) Appalachian oak – pine forest systems.


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