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Acidic Cliff

Scientific Name: Acidic Cliff - Gorge; State Rank: S1

photograph of an acidic cliff gorge

Community Description: Sparse vegetation occurs on steep outcrops or cliffs of granitic or other acidic rock. Marginal wood fern and rock polypody are characteristic ferns; fragrant wood fern can be found on cooler sites. Rock tripe lichens may form extensive patches. Back to top.

photograph of an acidic cliff gorge

Soil and Site Characteristics: Sites occupy nearly vertical to vertical outcrops of non calcareous, erosion resistant rocks. Most are dry, with large unvegetated areas; a moist microclimate is maintained over local areas by runoff or seeps from higher elevations, or, in gorges, by the flowing streamwater. Smaller ledges and outcrops (e.g., less than 5,000 square feet of rock exposure) should be considered as inclusions in the surrounding forest rather than distinct natural communities. Back to top.

Diagnostics: Sparsely vegetated cliffs occur below treeline, without circumneutral indicator species. Back to top.

Similar Types: Circumneutral Outcrops have circumneutral indicator species such as shrubby cinquefoil or certain uncommon herbs. Low Elevation Balds are on summits, not cliffs, and usually have heath shrubs mixed with the herbs. Back to top.

Conservation, Wildlife and Management Considerations: Many sites are relatively inaccessible and minimally affected by either forestry or recreational activities. Several are within public lands or conservation ownership.

Common ravens, peregrine falcons, and golden eagles may nest on cliffs in western, northern and coastal Maine. Back to top.

Distribution: Essentially statewide except for extreme southern Maine, more common northward. Landscape Pattern: Small Patch. The minimum mapping unit is 5,000 square feet of rock exposure; smaller ledges and outcrops should be considered as inclusions in the surrounding forest rather than distinct natural communities. Back to top.

map showing statewide distribution of acidic cliff gorge in Maine map legend

Characteristic Plants: These plants are frequently found in this community type. Those with an asterisk are often diagnostic of this community.

  • Herb
    • Brownish sedge
    • Common hairgrass
    • Marginal woodfern
    • Rand's goldenrod
    • Rock polypody
  • Bryoid
    • Rocktripe lichen

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Associated Rare Plants

Associated Rare Animals

  • Golden eagle
  • Peregrine falcon

Examples on Conservation Lands You Can Visit

Example County
Deboullie Ponds Public Lands Aroostook Co.
Dunn Falls, Appalachian Trail Oxford Co.
Grindstone Falls Penobscot Co.
Mount Kineo Public Lands Piscataquis Co.
Tunk Mountain, Donnell Pond Public Lands Hancock Co.

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photograph of an acidic cliff gorge