High Elevation Cliffs and Rock Outcrops
The 2015 North Carolina Wildlife Action Plan defines 41 priority habitats for the state. More information about this habitat can be found in Section 4.4.7.
Contents
Habitat Priorities
Surveys
- Survey for new Peregrine Falcon nests. (Surveys Priority)
- Obtain baseline data on small mammal communities and reptile communities and habitat use (e.g., identify Timber Rattlesnake den sites). (Surveys Priority)
Monitoring
- Monitor endemic species closely for declines in the near future. Transplantation may be required to prevent extinction.
- Continue monitoring the Peregrine Falcon population.
- Monitor priority mammal and reptile population trends and habitat use.
Research
- Study Timber Rattlesnake movements, use of hibernacula, and reproductive success at gestation sites.
- Reintroduce rare species to patches or mountain ranges where they have been lost, as well as to restored areas, to improve their prospects for survival in the future climate.
Management Practices
- Maintain biologically significant areas, including Peregrine Falcon nesting areas, reptile den sites, and significant salamander occurrences through active management of outcrops to reduce the intrusion by alder, rhododendron, and other species that contribute to the disappearance of some vertebrates.
- Control invasive species and protect or restore areas already affected by invasive species to protect against changing climate conditions.
- Use a hand crew to manually cut down encroaching woody vegetation with chainsaws or brush blades. Any use of herbicides and surfactants will need to be of low toxicity to wildlife.
Conservation Programs and Partnerships
Description
High-elevation rock outcrops are extremely rare, have a very restricted range, and are subject to extreme environmental conditions. These communities occur on ridge tops, peaks, and upper slopes where soils are thin and discontinuous and rock dominates the surface. Even in the most rugged high Mountains they represent only a small minority of the landscape, generally at 4,000 feet in elevation and higher. In contrast, mid-elevations range from 2,000 to 4,000 feet and low elevations are below 2,000 feet. The vegetation is likely to be very patchy, reflecting the variability of the soil. Two community types are part of this ecosystem: high-elevation granitic domes and high-elevation rocky summits.
- High-elevation granitic domes occur on the exfoliated outcrops that form when massive granitic rock breaks off in sheets parallel to the surface. Exfoliation produces smooth dome-shaped outcrops that lack crevices. Lichens and mosses occur on the bare rock. Soil and vegetation develop together on the rock surface as moss mats gradually deepen and are invaded by a succession of herbs. Soil mats are not anchored to the rock below and eventually fall off or are pulled up by falling trees, leaving the rock bare again. The shallow soils are generally dry, but some zones of seepage are usually present on the edge of the soil of adjacent forests. A number of wetland plants can occur in these saturated areas.
- High-elevation rocky summit communities occur on fractured rock. The bare rock is similarly vegetated by patches of lichen and moss, and shallow soil mats may develop locally. The presence of fractures, however, offers patches of deeper, more permanent soil that can support deeper rooted plants, and can provide an opportunity to anchor soil mats. The vegetation pattern is less likely to shift over time.
The 2005 WAP describes high elevation rock outcrops in the Southern Blue Ridge Mountains as a priority habitat (see Chapter 5) (NCWRC 2005).
Location of Habitat
High-elevation cliffs and rock outcrops occur only in the highest mountain ranges within the Mountain ecoregion in the Great Smokies, Plott Balsams, Great Balsams, Black/Craggy Mountains, Grandfather Mountain, Roan Mountain, and in the Amphibolite Mountains of Ashe County. According to the most recent Southeast GAP analysis, rocky summit and granitic domes comprise approximately 1,180 acres (about 478 hectares) of land cover in North Carolina (SEGAP 2007; NatureServe 2007).
Problems Affecting Habitats
The conditions present at individual rock outcrops are unique, owing to geology, geography, elevation, moisture, and landscape position. They may contain discrete communities or they may be dispersed among a variety of other community types that are connected through local geology and landscape conditions. As such, the extent of habitat that each rock outcrop provides is dependent upon the entire set of conditions in and surrounding the surface rock. Those conditions influence its use by plants and animals dependent upon the surface rock and may include significant amounts of adjacent ecological community types.
Common threats across the range of high-elevation rock outcrops include recreation, development, and forest succession. The two major problems most associated with low-elevation rock outcrops include development and recreational impacts. However, low-elevation rock outcrops are subjected to short-term habitat alterations (e.g., forestry operations) more often than high-elevation rock outcrops due to land ownership patterns, proximity to markets, accessibility, and other factors.
Climate Change Compared to Other Threats
Comparing climate change to other ecosystem threats can help define shortand long-term conservation actions and recommendations. While climate change is not the most severe threat, a combination of synergistic effects with other existing conditions could stress these systems to the point where several species are unable to persist.
The effect of a changed climate is likely to vary widely among examples of these communities, depending on topographic sheltering, configuration of rocks and soil depth. These systems are tied to specialized small environments and will be unable to migrate as the climate changes. Many may change very little, while a few will shrink, will be disturbed by wind or flood, or will change substantially because of temperature changes or drought.
Impacts to Wildlife
While high-elevation rock outcrop habitat and low-elevation cliffs/rock outcrops support many of the same animals and plants, there are species of both plants and animals that are found exclusively at high-elevation rock communities (e.g., the Rock Vole, Long-tailed Shrew, Allegheny Woodrat, and several rare plant species), and others found only in low-elevation cliffs/rock outcrop habitats (e.g., the Southern Appalachian Woodrat, Spotted Skunk, and Crevice, Green, and Southern Zigzag salamanders). The elevation limit for each of these species varies; however, there are distinctions in animal assemblages in rock habitats that are defined by elevation.
For many species associated with high-elevation rock outcrops, we do not currently know the entire spectrum of threats that are affecting populations due to inadequate levels of study or knowledge. Individual wildlife and plant species may face threats specific to either their particular location or the species itself. For example, Timber Rattlesnakes face threats in addition to habitat loss, including being subject to collection, disturbance of hibernacula/gestation sites, and persecution. There has been considerable effort undertaken in the northeastern United States to determine the impact upon Allegheny Woodrat populations from a roundworm parasite that may have impacted populations in that region (McGowan 1993; Stone et al. 1993), though no studies have been conducted within North Carolina to assess the level of threat posed to North Carolina woodrat populations.
The decline of Peregrine Falcons during the last half of the 20th century has been widely attributed to the use of DDT and its concomitant effect on bird reproduction. The use of DDT was banned and Peregrine Falcon restoration efforts occurred in the late 1980s and 1990s; however the falcons still face threats due to habitat loss to development and recreation impacts at individual cliff sites. Furthermore, the North Carolina population remains at fairly low density, thereby increasing the threat of stochastic events having significant population impacts.
The insect fauna of high-elevation rock outcrops is not yet well studied and a number of additional species may yet be added. The landscape requirements of these guilds also need more study. Two endemic spiders in the Lampshade genus (Hypochilus) would be particularly vulnerable to extinction if they are intolerant to increases in temperature and drought, which seems likely (Huff and Coyle 1992). Their current restriction to extremely small ranges suggests that they have only a low level of dispersal ability and may be unable to shift their ranges fast enough to keep up with environmental change. Competition with the more widespread Lampshade Weaver (H. pococki) spider may further limit their ability to shift their ranges.