Wet Pine Savannas
The 2015 North Carolina Wildlife Action Plan defines 41 priority habitats for the state. More information about this habitat can be found in Section 4.3.11.
Contents
Habitat Priorities
Surveys
Monitoring
- Initiate long-term monitoring once baseline surveys have been conducted. Focus should begin with herpetofauna and bird species in decline, or for which little is known about the population fluctuations and demographics.
Research
- Determine better ways to construct fire lines and better ways to burn around populated areas where smoke would otherwise be a concern when burning.
- Determine how to effectively restore altered portions of this habitat type and develop methods to manage them without fire.
Management Practices
- Establish examples of well-maintained and burned savannas as demonstration sites for landowners to emulate. Burning should be accomplished without placing firelines in transition zones from uplands to wetlands and with the fire allowed to burn through transition zones.
- Habitat restoration should primarily occur through growing season prescribed burning, to develop and maintain the herbaceous layer and open pine stands. Where growing season burns cannot be administered, winter burns can be constructive. Burning should be accomplished without placing firelines in transition zones from uplands to wetlands and with the fire allowed to burn through transition zones.
- Snags should be retained during logging operations to increase the numbers available for cavity-using wildlife species.
- Maintain sufficient levels of woody debris in stands for reptiles, amphibians, and small mammals.
- Create borrow sites or ponds for breeding use by amphibians. Otherwise, amphibians are scarce in most flatwoods and savannas devoid of pools or open water.
- Watch for arrival of Cogon Grass and other new invaders and control promptly.
Conservation Programs and Partnerships
Description
The communities in wet pine savannas are Coastal Plain mineral soil wetlands that under natural conditions were frequently burned. With frequent fire, they have an open canopy dominated by longleaf or pond pine over a grassy herb layer. Shrubs are short and sparse with frequent fire, but become dense if fire is suppressed for more than a couple of years. There are three community types in this ecosystem group: pine savanna, sandhill seeps, and wet pine flatwoods.
- The pine savanna type occurs in flat areas that are saturated or even slightly flooded during the wetter parts of the year. The herb layer is dominated by grasses and sedges and a variety of low shrubs may be present, but are low and open if the savanna is frequently burned. The herb layer usually contains many showy composites, orchids, and insectivorous plants. One of the most notable features of pine savanna communities is their tremendous plant diversity at small scales.
- Sandhill seeps occur on sloping seepage areas, where the wettest parts are essentially permanently saturated. They share many species with the pine savanna type but are more heterogeneous and more bog-like in character. In frequently burned seeps, grassy and sedgy areas can have a high diversity of plants, rivaling the pine savannas in species richness at small scales.
- Wet pine flatwoods communities usually occur in flat areas, though sloping areas are possible. They resemble pine savannas in general structure, with an open pine canopy over a grassy ground cover with low shrubs. Wiregrass is always the dominant herb. Shrubs become dense if fire is excluded. Unlike pine savannas, the herb diversity is low: in many cases, only one to five species may be present in a square meter.
The 2005 WAP describes Mid-Atlantic Coastal Plain wet pine savannas as a priority habitat (see Chapter 5) (NCWRC 2005).
Location of Habitat
The Green Swamp, Holly Shelter, and Sandhills Game Lands and the Croatan National Forest contain good examples of this habitat.
Problems Affecting Habitats
Intensively managed pine plantations, urban development, a lack of fire, and subsequent habitat fragmentation continue to threaten these communities. Climate change may exacerbate some of these problems. New alternative energy development in the region, such as natural gas fracking and biofuel harvesting, may be an emerging threat but it is uncertain what direct effect these will have on wildlife. Anticipated indirect impacts will include displacement from loss of habitat and loss of connectivity due to habitat fragmentation. Table 4.25 identifies the most important threats and summarizes the anticipated impacts.
Although no invasive exotic plants are a serious problem in these systems now, early detection and control of invasive exotic species (such as Cogon Grass) will reduce the ecological damage caused by invasives and the cost of controlling them. Preventative measures such as forbidding sale and transport of invasive species will help reduce the risks and cost. Fire Ants are already a serious cause for concern for many of the animal species that inhabit savannas.
These systems occur mostly in low-lying areas that are unlikely to become extremely dry even in droughts. Sandhill seeps are probably more vulnerable than other community types in this group because they depend on movement of shallow ground water. Droughts would dry them up, perhaps enough for plants to experience water stress. Many species excluded from them at present by wetness may be able to invade with drought.
Increased drought conditions and increased thunderstorm intensity may lead to more wildfires. These systems depend on fire and are often degraded by lack of fire. An increase in wildfires may allow some occurrences to burn in a way that is ecologically beneficial. However, wildfires in drought may be more likely to be too intense or extensive and to harm some species.
If droughts are frequent enough, species of drier communities that are currently excluded by wet periods may be able to establish in them. While species of dry Longleaf Pine communities are presumably excluded from wet pine savannas by moisture, most other species are excluded more by frequent fire. Composition is unlikely to change much for sites that can be burned.
Longleaf Pines are among the least susceptible trees to wind destruction, and it is unclear how significant increases in wind storms will affect them. Pines with nest cavities of the endangered Red-cockaded Woodpecker frequently snap at the cavity site because much of the internal wood has been removed by the birds. General forecasts suggest an increase in severe storms may cause more wind damage to canopy trees, especially to those with woodpecker nest cavities.
Flammability of pocosins varies with season and a change in seasonal phenology that makes them flammable earlier in the season would limit prescribed burning in savannas. Changes in phenology can disrupt pollinator and predator–prey relationships. Warmer temperatures may allow an increase in abundance or rate of spread of Fire Ants and other invasive species. Mild winters, with decreased cold damage, may allow species from the south to move into North Carolina.
These systems range well to the south of North Carolina. They and their component species are well adapted to warm temperatures. Increased temperatures might increase the range of these systems in the northern Coastal Plain and in Virginia. Most plants in these systems have limited dispersal ability even locally, so any influx of native species from the south is likely to be slow. The widespread conversion of potential sites in this region, the fragmented distribution of examples, and their dependence on fire make natural expansion difficult.
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, soil depth, size of groundwater pools, and amount of overland runoff. 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. A small net loss of acreage may occur, but more seeps may be temporarily affected by drought.
Impacts to Wildlife
Appendix G provides a list of SGCN and other priority species for which there are knowledge gaps and management concerns. Appendix H identifies SGCN that depend on or are associated with wet pine savannas.
These habitats are particularly important for reptiles and amphibians where ponds are embedded in savannas or flatwoods; such species include Carolina Gopher Frog, Ornate Chorus Frog, and Southern Chorus Frog. Several reptile species, such as Pigmy and Timber (Canebrake) rattlesnakes and Mimic Glass Lizard, are found in savannas and pine flatwoods away from pools and ponds. Many of the bird species of highest conservation concern inhabit these communities and depend on frequent fire to create suitable habitat conditions (e.g., the Red-cockaded Woodpecker, Bachman's Sparrow, Henslow's Sparrow, Brown-headed Nuthatch, American Kestrel, Prairie Warbler) (Hunter et al. 2001b; Johns 2004). Game species such as the White-tailed Deer, Northern Bobwhite Quail, Wild Turkey, Eastern Cottontail Rabbit, Gray Squirrel, and Eastern Fox Squirrel also utilize this habitat for forage and cover.
Red-cockaded Woodpeckers use these habitats, because they typically have a sparse overstory and open midstory that is preferred by the woodpeckers. Increased wind storm damage could affect canopy structure and topple some nesting cavity trees. Because of the slow reproductive rate and long life span of Longleaf Pine, increased wind mortality would reduce average age and might reduce natural canopy density. This would be detrimental to Red-cockaded Woodpeckers and other species that depend on older longleaf pine trees.
Three species of insects are endemics or near-endemics to wet pine savanna habitats in North Carolina. Five others are major disjuncts, with their next nearest populations in New Jersey, Florida, or in the case of Rattlesnake-Master Borer moth, the tallgrass prairies of the Midwest. The Coastal Plain Apamea moth appears to have a highly disjunct population in the coastal savannas but also occurs in the Southern Appalachians.
Fire suppression and a lack of growing-season prescribed burning causes a thick shrubby understory to develop which shades out grasses and herbaceous ground vegetation and greatly reduces overall plant and animal diversity. Microhabitats and ecotones can be impacted by fire line construction, and a lack of woody debris particularly impacts reptiles, amphibians, and small mammals.
While all of these species are associated with fire-maintained habitats, the majority depend on having a metapopulation structure to cope with fire, as well as other environmental perturbations. Five of these species have substantially lost their metapopulation structure and have become highly vulnerable to the effects of single catastrophic events, including wildfires. Because many examples of this habitat are now fragmented and isolated, uncontrolled fire that burns whole patches is a significant threat to many insect populations. In Summer 2009, a backfire to control a wildfire in Croatan National Forest burned the entire known habitat of the Arogos Skipper; this butterfly has not been seen there or anywhere else in the state since that fire.