Chapter 4 Habitats
Addendum 2
Monadnock sites tend to be dry. Increased dryness might stress chestnut oaks, but it is unclear how serious this is; they do not appear to be limited by moisture at present. The shortleaf pine component may increase, particularly if there is more fire. Most species will probably persist but those that are confined to monadnocks or other small patches of habitat may be vulnerable to increased perturbations, such as fire, if their entire block of habitat is affected by any one event. • Xeric Hardpan Forests are rare Piedmont communities that are intermediate between oak-hickory forests and glade or barrens habitats. They occur on upland flats where soils high in shrink-swell clays interfere with water penetration and root growth. Most are on diabase or gabbro and have species typical of the less acidic conditions, but an even rarer subtype occurs on acidic shales. The distinctive soil properties produce conditions that appear drier than Dry Oak — Hickory Forest, drier than the climate of North Carolina would suggest. Nevertheless, these communities are often associated with Upland Depression Swamp Forest communities. The canopy is dominated by some of the most drought tolerant species in the state, post oak and blackjack oak, and in mature stands the canopy is somewhat open. With the persistent fire regime that once prevailed across the Piedmont, these forests would be more open, appearing as woodlands or savannas, perhaps with open prairie patches on the most extreme soils. While dense brush is often found beneath the open canopy now, these communities presumably were once open and grassy beneath. Numerous plants that need full sunlight are present in canopy openings and along maintained edges such as roadsides and powerline corridors in areas where Xeric Hardpan Forests occur. Drought will likely shift them to more open structure that resembles their natural condition, perhaps even without increased fire. • Mixed Moisture Hardpan Forest communities are dominated by a mixture of tree species typical of hydric and xeric conditions, occurring on sites with clay-rich soils that have restricted internal drainage or shrink-swell properties. Typically, willow oak is mixed with white oak, post oak, or southern shagbark hickory as the predominant canopy. Mixed Moisture Hardpan Forest is distinguished by the co-occurrence of wetland and upland oak and hickory species, generally including both willow oak and post oak in significant numbers, without segregation into distinct Xeric Hardpan Forest and Upland Depression Swamp communities. The site generally shows evidence of shallow ponding of water but not water flow. Mixed Moisture Hardpan Forests occur on unusually flat upland areas of the Piedmont, generally associated with diabase, gabbro,
2022 Addendum 2 NC Wildlife Action Plan
4A2- 3
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