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Monadnock

Sites

Monadnocks and high ridges, generally on quartzite, rhyolite, or other highly resistant rocks.

Soils

Rocky, well-drained, generally very acidic soils. Series include Georgeville, Goldston, Herndon, Tarrus, and Wedowee.

Hydrology

Terrestrial, dry to xeric.

Vegetation

Canopy

The canopy is strongly dominated by Quercus montana (Rock Chestnut Oak), occasionally codominated by Q. coccinea (Scarlet Oak). Other canopy trees may include Q. alba (White Oak), Q. marilandica (Blackjack Oak), Q. stellata (Post Oak), Q. falcata (Southern Red Oak), Carya glabra (Pignut Hickory), C. tomentosa (Mockernut Hickory), Pinus echinata (Shortleaf Pine) and P. virginiana (Virginia Pine).

Understory

The understory is typically strongly dominated by Oxydendrum arboreum (Sourwood) and Acer rubrum (Eastern Red Maple), with some Nyssa sylvatica (Black Gum), Cornus florida (Flowering Dogwood) and other species. A patchy shrub layer may consist of Vaccinium stamineum (Common Deerberry), V. pallidum (Hillside Blueberry), Gaylussacia spp. (Huckleberry) or Vitis rotundifolia (Muscadine).

Herb Layer

The herb layer is sparse, with Chimaphila maculata (Pipsissewa), Hieracium venosum (Veiny Hawkweed), Danthonia spicata (Poverty Oat-grass), Coreopsis verticillata (Threadleaf Coreopsis), Hylodesmum nudiflorum (Naked Tick-trefoil), Tephrosia virginiana (Virginia Goat’s-rue), Schizachyrium scoparium (Common Little Bluestem) and Pteridium aquilinum (Eastern Bracken) also characteristic.

Dynamics

The exposed position of monadnocks makes these forests very susceptible to disturbance by high winds and lightning. Canopy gaps are probably larger and more frequent than in most Piedmont forests, but forests are generally uneven-aged and often contain old trees. Monadnocks are likely sites for lightning fires to start, as well as being very susceptible to fires spreading from below. They may have burned more frequently than most Piedmont communities. Because the herb layer is sparse and the component species fire tolerant, fires may have had little effect on community composition or structure.

Associations

Grades downward to Dry or Dry-Mesic Oak-Hickory Forest. May grade into Acidic Cliff or Heath Bluff. May rarely grade to Pine-Oak Heath on sharp high ridgetops.

Comments

Monadnock Forests are generally very low in plant diversity and not all isolated hills support this community type. The abundance of rock may be an important factor in determining its occurrence, as may soil chemistry. Extreme soil acidity, accompanied by aluminum toxicity, has been suggested as important.