Natural Community Systems -- Photo Guide

Montane acidic talus system

montane acidic talus system at Magalloway Mtn. in northern NH (photo by Bill Nichols for the NH Natural Heritage Bureau)
montane acidic talus system at Magalloway Mtn. in northern NH (photo by Bill Nichols)

a large, lichen-covered talus block in the montane acidic talus system in Ice Gulch (photo by Ben Kimball for the NH Natural Heritage Bureau)
a large, lichen-covered talus block in the montane acidic talus system in Ice Gulch (photo by Ben Kimball)


DescriptionTalus consists of jagged, chaotic masses of angular rocks precariously perched on steep slopes below cliffs.  Over time, the freeze-thaw action of water in cracks forces blocks of rock to separate and fall from the cliff.  In New Hampshire, the most famous example of this phenomenon occurred in 2005, when the rock formation known as the Old Man of the Mountain fell from its perch on Cannon Cliff onto the talus slope below.  Talus slopes may be large or small, and are found throughout the state from sea level to the alpine zone.  Talus slopes are extremely diverse physical environments, where rock size and slope stability, soil development, and climate vary greatly within and among examples.

Montane acidic talus slopes are found at mid to high elevations in the White Mountains and are characterized by spruce, fir, and various other northern species.  This system tends to have an open woodland character, with frequent canopy gaps and lichen-dominated talus barren openings.  Soil development is variable on these slopes, and moisture conditions range from dry to mesic.  Larger examples have giant talus blocks at their base with late-melting ice that produces a cold, moist microclimate supporting alpine plants well below treeline.  Most occurrences of this system are found above 2,200 ft. elevation, but occasionally found down to about 1,500 ft.  This system includes a few lower elevation “talus gorges” such as Ice Gulch and Devil’s Hopyard.  Talus areas that are completely forested with no openings or woodland structure are likely to be better classified as a rocky example of a sugar maple - beech - yellow birch forest, high-elevation spruce - fir forest, or northern hardwood - spruce - fir forest natural communities.

The main community (birch - mountain maple wooded talus) in this system is partially wooded and has a patchy understory of shrubs, herbs, and sometimes dense carpets of bryophytes.  Subalpine cold-air talus shrublands correspond to talus areas with large, ice-cooled boulders where the microclimate supports black and red spruce, heaths and evergreen shrubs, and lichen and mosses characteristic of alpine and montane habitats.  Mosses and lichens are abundant but not well documented to the species level.  Herbaceous species are notably sparse or absent.  Little is specifically documented about the biota in lichen talus barrens, but crustose, umbillicate, and foliose lichens are prominent.

Diagnostic natural communities:

      • Birch - mountain maple wooded talus (S3)

      • Subalpine cold-air talus shrubland (S1)

      • Montane lichen talus barren (S3)

      • Montane landslide barren and thicket (S3S4)

      • Spruce - moss wooded talus (S2S3)

Peripheral or occasional natural communities:

      • Alpine/subalpine pond (S1)

Landscape settings: most common below cliffs on steep, mid- to lower-slope positions (concave or neutral slope); occasionally found in deep talus gorges or without a cliff

Soils: variable soils including no soil development on open talus; coarse to fine mineral colluvium accumulation among talus boulders or in gullies, often mixed with organic matter; with or without shallow organic layer development

Spatial pattern: small to large patches (<1 to 100’s of acres); variable shaped but often somewhat linear-elliptical along base of cliff

Physiognomy: woodlands, sparse woodlands, and open talus with trees, herbs, shrubs, bryophytes, and/or lichens

Distribution: mid to high elevations in the White Mtns (mostly above 2,200 feet, occasionally to 1,500 ft.)

Characteristic species:

Birch - mountain maple wooded talus:
Trees and tall shrubs
   Betula papyrifera (paper birch)
   Betula cordifolia (heartleaf birch) 
   Betula alleghaniensis (yellow birch) 
   Sorbus americana (American mountain ash)
   Sorbus decora (showy mountain ash)
   Acer spicatum (mountain maple)

Herbs, short shrubs, and vines
   Polypodium virginianum (rock polypody)
   Parthenocissus quinquefolia (Virginia creeper)
   Polygonum cilinode (fringed bindweed)
   Vaccinium angustifolium (lowbush blueberry) 
   Deschampsia flexuosa (common hair-grass) 
   Vaccinium myrtilloides (velvet-leaf blueberry) 
   Solidago randii (Rand’s goldenrod) 
   Juncus trifidus (highland rush)
   Ribes glandulosum (skunk currant)

Spruce - moss wooded talus:
Trees and tall shrubs
   Picea rubens (red spruce)
   Abies balsamea (balsam fir)

Herbs and short shrubs
   Vaccinium vitis-idaea (mountain cranberry)
   Clintonia borealis (bluebead lily)

Mosses and liverworts abundant

Subalpine cold-air talus shrubland:

Dwarf shrubs
   Ledum groenlandicum (Labrador tea)
   Kalmia angustifolia (sheep laurel)
   Empetrum nigrum (black crowberry)
   Empetrum atropurpureum (purple crowberry)
   Vaccinium vitis-idaea (mountain cranberry)
   Vaccinium uliginosum (alpine bilberry)
   Vaccinium myrtilloides (velvet-leaf blueberry)
   Vaccinium angustifolium (early low blueberry)
   Rhododendron canadense (rhodora)
   Gaultheria hispidula (creeping snowberry)

Mosses and liverworts abundant
Crustose, umbillicate, and foliose lichens abundant

Associated natural community systems: Montane acidic talus slopes are often, but not always, found below montane cliff systems, and surrounded by either northern hardwood or high-elevation spruce – fir forest systems.

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