Prescribed Fire in Pocosins and Large Shrub Bogs

Prescribed fire is used in pocosins for fuel management and for the maintenance of biodiversity and natural processes (Bucher and High 2000). It is also used for silvicultural purposes such as site improvement, pond pine seedling establishment, and for fire hazard reduction during early pine growth (Christensen 1981, Taylor and Wendel 1964).

Implementing a prescribed fire program in large tracts of pocosin vegetation is more difficult than in many other plant communities. Domed peatlands are large in extent, with very high fuel loads situated on organic soils where access is difficult. Several key operational issues emerge in burning pocosins:

1. Burning large blocks of vegetation is rarely feasible due to fire control issues and restrictions on smoke production, particularly in a community type that only sustains fire under droughty conditions. Thus, blocks need to be broken up into manageable units.
2. When creating firebreaks in wetlands, wetland permits must be sought from appropriate local, state and federal agencies. Pocosins are regulated under Section 404 of the Clean Water Act and activities within pocosins require permits from the Army Corps of Engineers. The ecological effects of ditched firebreaks must also be considered.
3. The width of firebreaks required to control fires in pocosins is also larger than in most other community types. Firebreak widths of 1.5 to 2.5 times the flame length are recommended by National Wildfire Coordinating Group, which result in firebreak widths of 15-60 ft wide depending on conditions.
4. There is uncertainty in using prescribed fires in areas with organic soils because
   • Igniting a ground fire, though sometimes desirable from an ecological perspective, can be hazardous because of excessive production of smoke resulting from smoldering ground fires.
   • Factors that determine ignition and sustained burning of organic soils have only recently received intensive study and in the past, literature was often confusing regarding safe conditions under which burning could be conducted.
   • Smoldering ground fires are often hard to extinguish, can go on for long periods and create potential for fires to re-ignite and for escapes. Some of these concerns may be ameliorated where water control structures are present such that the water table may be manipulated to assist in extinguishing ground fires as needed.

Several of these factors make fire practitioners uncomfortable using fire in pocosins but, despite these challenges prescribed fires have been safely applied to pocosin vegetation (Hungerford et al.1998, Bucher and High 2000).

In addition to operational considerations, ecological factors to consider in burning pocosin vegetation include:

1. Planning for ground fires that promote openings that support not only herbaceous species but also rare plant species is important to maintain diversity.
2. Maintenance of diversity involves considerations of frequency and the patch mosaic in which past fires have burned, because plant diversity is highest soon after fires (Christensen 1981).
• Robertson et al. (1998) have recommend, as an approximation, burning low pocosin every 20 years and that the need for burning can be assessed by the extent of herbaceous openings.
• The same authors suggest burning high pocosin on 5 to 8 year intervals. This fire return interval is at the more frequent end of the cited historical return interval because the authors were promoting the restoration of canebrake communities. Managing for pure canebrake communities may promote a less diverse community because of the often monotypic stands of cane that can develop in pocosins under a frequent fire regime (Frost 1995). When setting a target fire return interval, consider objectives with regard to diversity.
3. The presence of rare plants may necessitate a particular fire regime and depending on the plant, different regimes may be prescribed (Robertson et al. 1998). Life history information on the species of concern should be consulted when it is available.