• IMMEDIATE FIRE EFFECT ON PLANT
• DISCUSSION AND QUALIFICATION OF FIRE EFFECT
• PLANT RESPONSE TO FIRE
• DISCUSSION AND QUALIFICATION OF PLANT RESPONSE
• FIRE MANAGEMENT CONSIDERATIONS

IMMEDIATE FIRE EFFECT ON PLANT:

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:

Not only were mean concentrations of particular nutrients elevated following fire, but spatial variation in those concentrations was also increased. This was particularly true for nitrogen and phosphorus. Thus, high and low nutrient patches were created in an area characterized by uniformly low prefire nutrient concentrations. This redistribution of resources might lead to the creation of patches of high and low production within a bog [87].

PLANT RESPONSE TO FIRE:

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

Heat generated by a ground fire is usually of sufficient intensity to open the serotinous cones of pond pine [6]. Pond pine cones do not characteristically remain closed for longer than 4 to 5 years [79], and observations suggest that cones open rapidly on felled trees during midday on clear summer days [6,83] when the outside temperature may be sufficient to open the cones. Seeds up to 14 years old have been germinated [83]. Pond pine cones germinate best after a burn on soil that is moist. This may be because the root system of pond pine is superficial and the seedlings many not be able to obtain enough water to survive in dry conditions [6].

Fire removes competition, exposes the soil and causes the seed of pond pine to fall. Volume of seed caught in traps averaged about 3,000 sound seed per acre per year for undisturbed and unburned seed tree stands. From 2 uncut but burned stands the average was 53,000 sound seed/acre over a 6-week period following the burn [16]. After a fire on Cumberland Island, Georgia, pond pine, loblolly pine, and slash pine reseeded where the pine canopy was killed [9].

Season of burning is largely determined by availability of ignition sources and seasonal variation in fuel flammability. A major factor affecting flammability is seasonal variation in moisture. Seasonal variation in the dead-to-live ratio is also important in shrub bogs [14]. Low-severity winter fires are valuable in preparing favorable seedbeds for establishment of pine seedlings and in partially controlling associated hardwoods [43]. Most wildfires in the pocosins occur during the early spring and before the evergreen vegetation has increased its moisture content through spring growth [44].

FIRE MANAGEMENT CONSIDERATIONS:

Fire exclusion is an unrealistic management objective for sustaining ecological communities, such as those containing pond pine, that are adapted to and dependent upon recurring fires to maintain balance. Prescribed burning is a more reasonable management goal as it approximates natural processes inherent to a fire region.  Under natural conditions, frequent fires maintain vegetation, recycle nutrients, and drive vegetation cycles [76]. However, because seedlings are either killed outright or set back by fire during their early years, prescribed burning is not recommended for most pine species until they are at least 9.8 to 13 feet (3- 4 m) tall [75], and too frequent burning of pond pine at any age may eliminate the species from an area altogether [26].

Prescribed fire appears to be a potentially valuable tool in the management of pond pine by promoting seed fall from the serotinous cones and in preparing the seedbed. Fires of sufficient intensity to achieve these results, however, are usually difficult to control and tend to burn deeply into the organic soil. The problem has become more acute in the past 10 years because of increased commercial importance of pocosins as pulpwood and timber processing areas [85]. Following harvest of mature pines, flatwoods sites are often prepared for pine regeneration by use of prescribed fires. Objective of this burning is to consume as much surface litter and remaining understory biomass as possible, creating a site easy to plant by machine and removing potential competing vegetation. Burning is also often used in established stands to reduce potential for hazardous fire in young stands and to control disease and insect pests [2].  

Although recommendations for optimum season of burns of southeastern forests are somewhat contradictory, Streng, Glitzenstein, and Platt [71] concluded that growing season burns do not reduce growth or survival of pines more than do dormant season burns; therefore, growing season prescribed burns can be conducted without undue fear of creating damaging fires.

In North Carolina pocosins, growth and vigor of pond pine seedlings are much better on burned-logged areas than on burned-unlogged. It is speculated that there is less root and top competition for seedlings on the burned-logged areas. Seedlings that germinate during the 1st, 2nd, or 3rd years following logging and burning have the best chance of surviving competition with the brush [6]. Although logging opened up the tree canopy of a Coastal Plains pond pine forest, it did not significantly affect seedling establishment. Rate of seedling establishment was extremely low on unburned sites regardless of logging treatment [66]. 

Grazing of pond pine habitats without a fire disturbance may be beneficial to pond pine establishment, although grazing after a fire may reduce the number of pond pine seedlings. The average number of new pond pine seedlings per acre that became established in grazed and ungrazed plots before and after fire disturbance in the southern Coastal Plains follows [66]: