Natural Community Systems -- Photo Guide

Rich north-temperate talus/rocky woods system

Rich north-temperate talus/rocky woods system on North Mtn. in Pawtuckaway State Park (photo by Dan Sperduto for the NH Natural Heritage Bureau)
Rich north-temperate talus/rocky woods system on
North Mtn. in Pawtuckaway State Park (photo by Dan Sperduto)

 

Description:  This system is found on enriched talus and other rocky slopes in central New Hampshire from about 500 to 1,200 ft. elevation, and occasionally up to about 2,000 ft. in the low elevation valleys in the White Mountain region (Saco, Connecticut, and Androscoggin River valleys).  The primary diagnostic community is rich red oak rocky woods, but the larger talus slope often has patches of temperate lichen talus barren, and occasionally patches of rich mesic forest or semi-rich mesic sugar maple forest communities in moist, colluvial areas at the base of the talus slopes.  A few examples at intermediate elevations in the White Mountains (around 1,500 ft.) include patches of birch - mountain maple wooded talus, which is otherwise indicative of montane acidic talus systemsMontane acidic talus systems lack rich-site indicators, and on average occur at higher elevations and in the mountains well above the lowest elevation valley bottoms.  This system differs from Appalachian rocky woods system by the absence of southern oaks and southern species restricted to extreme southern New Hampshire at low elevations (<500 ft.); both are drier and rockier than rich mesic forests (overall dry-mesic). 

Tree canopy dominants usually include Acer saccharum (sugar maple) and Quercus rubra (red oak), with lesser amounts of Ostrya virginiana (ironwood) and other hardwoods (softwoods are sparse or absent).  Understory shrub and herb species that prefer enriched conditions differentiate this community from acidic till or talus systems.  More open or unstable talus areas correspond to temperate lichen talus barrens where lichens are the dominant life-form.  Rich mesic forest patches can occur at the colluvial bases of some talus slopes, and are marked by the disappearance of red oak, ironwood, beech, and rich site vines or herbs more preferential to rich rocky talus such as Geranium robertianum (herb Robert), Oryzopsis racemosa (blackseed rice-grass), Clematis virginiana (virgin's bower), and Toxicodendron radicans (poison ivy).  Thus, small patches of rich mesic forest are characteristic of this system and do not necessarily indicate a larger rich mesic forest system.

Diagnostic natural communities:

      • Rich red oak rocky woods (S2S3)

      • Red oak - black birch wooded talus (S3S4)

      • Temperate lichen talus barren (S2S3)

      • Rich mesic forest (S3)

      • Semi-rich mesic sugar maple forest (S4)

Peripheral or occasional natural communities:

      • Birch - mountain maple wooded talus (S3)

      • Montane lichen talus barren (S3)


Landscape settings: talus or other rocky slopes in neutral to concave hillside slope positions, and occasionally upper-slope positions, particularly in regions of calcium-rich bedrock

Soils: overall dry-mesic with embedded dry and mesic micro-sites, well to somewhat excessively well drained; moderate to shallow depth fine sandy loams with considerable gravel and stone content with frequent outcrops, talus boulders, and/or unconsolidated stones; sometimes with a well-mixed “mull” A horizon

Spatial pattern: variable (<1–50+ acres), although often elliptical or broad-linear when controlled by topographic position (i.e., cliff-bases and hillside slopes)

Physiognomy: woodland to forest, with patches of un- or sparsely-vegetated lichen talus barrens

Distribution: low to mid elevations in central and southern New Hampshire (500–1,200 ft., occasionally to 2,000 ft.)


Characteristic species:
Trees
   Acer saccharum (sugar maple) -- dom.
   Quercus rubra (red oak) -- dom.
   Tilia americana (basswood)
   Fraxinus americana (white ash)
   Ostrya virginiana (ironwood)
   Betula lenta (black birch)
   Acer rubrum (red maple)
   Betula alleghaniensis (yellow birch)
   Betula papyrifera (paper birch)

Shrubs and vines (rich-site indicators)
   Cornus rugosa (round-leaved dogwood)
   Clematis virginiana (virgin’s bower)
   Toxicodendron radicans (poison ivy)
   Corylus cornuta (beaked hazel-nut)
   Rubus odoratus (purple-flowering raspberry)

Herbs (rich-site indicators)
   Saxifraga virginiensis (early saxifrage)
   Geranium robertianum (herb Robert)
   Juglans cinerea (butternut)
   Aralia racemosa (spikenard)
   Oryzopsis racemosa (blackseed rice-grass)
   Milium effusum (millet-grass)
   Asarum canadense (wild ginger)
   Carex rosea/radiata (rosey sedge)
   Carex platyphylla (flat-leaved sedge)
   Carex sprengelii (long-beaked sedge)

Potential rare species:
   Geranium carolinianum (Carolina cranesbill)
   Dentaria laciniata (cutleaf toothwort)
   Adlumia fungosa (climbing fumitory)
   Panax quinquefolius (ginseng)
   Carex aestivalis (summer sedge)


Associated natural community systems:  This system often transitions to montane rocky ridge and montane cliff systems upslope and northern hardwood – conifer forest or hemlock – hardwood – pine forest systems downslope.



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