The Wildfire Environment
The wildfire environment is the surrounding conditions, influences, and modifying forces that are in place as a fire is ignited. Fire itself is the result of complex interactions of aerodynamics, chemistry, thermodynamics, and combustion physics. The current state of each of these influences and their interactions may vary wildly over time and space. Fire behavior, therefore, is the interactions of the environmental components, generalized as fuels, weather and topography, with each other and with the fire at any particular moment.
Fire has played a significant role in the development and distribution of the natural communities found within the NJ Pinelands, and New Jersey in general. The New Jersey Pinelands is a fire adapted forest ecosystem that depends on wildfire for reproduction and the control of fuel buildup. This forest community is one of the most hazardous wildland fuel types in the nation. Pinelands fires burn extremely hot and spread rapidly. New Jersey’s high population density has created land use pressures in which more people are moving from urban areas to build homes in rural wildland areas. With more people living in, and enjoying the state’s wildlands for various forms of recreation, the number of fire starts and the seriousness of their consequences increases. A potentially explosive combination is created when the factors of hazardous wildland fuels, interface home development, and an increased risk of human caused ignition come together under extreme fire weather conditions.
The unique vegetation assemblages seen today in the NJ Pine Barrens region are the product of variety of factors. Local climate, amount and frequency of precipitation, and chemical and physical properties of endemic soils interact dynamically and set the stage on which plants must grow, compete, reproduce and die. This abiotic environment interacts with existing vegetation, available plant-propagules and exogenic, often human-derived, disturbances resulting in an ever-changing mosaic of plant communities in the New Jersey Pinelands - perhaps with greater frequency than in other areas of the state.
While the climate, precipitation and potential seed sources of the Pinelands do not differ profoundly from other areas of the state or Mid-Atlantic region, the general character of the soils differs markedly. Especially on the Outer Coastal Plain, soils tend to be sandier, more drought-prone and lower in many plant nutrients. Differences in these edaphic factors – especially limitations in available soil moisture - are ultimately responsible for the much of the unique vegetation in the region. Despite the fact that, like the rest of the state, our Pinelands average over 42” of rain-equivalent per-year, upland plant communities are all dominated by xeriphytic species adapted to establishment, growth and reproduction in drought-prone sites.
The compositions of these plant communities, as well as their vegetative and growth characteristics, are significantly affected by fire. Indeed, fire is cited as the primary agent of ecological disturbance in most upland vegetation types in the Pine Barrens. Many upland plant species have adapted to fire and some are dependent on it for reproduction. Some trees and shrubs produce new sprouts from stem and root buds after fire has killed the original growth of branches and leaves. The seeds of some are released when exposed to the heat generated by a fire and germinate readily on the relatively bare, sunny landscape that remains following fire. Other plants may be killed easily by fire and eliminated from an area due to inadequate sprouting capability, the destruction of viable seeds, or the absence of a suitable seedbed for reproduction.
It is this dependence on fire that makes the Pinelands so unique. Many of the State’s listed threatened and endangered species thrive in the open conditions that had historically resulted from the natural fire regime. Unfortunately, the development of homes in and around the area has necessitated quick suppression of wildfires, perpetuated the successional stagnation of the plant community, and thereby influencing the success of nearly all of these ecological communities.
To maintain native Pinelands ecological communities and associated biodiversity, management techniques necessitate the integration of prescribed fire and/or forestry practices to mimic the natural or historic disturbance processes. A variety of fire behavior characteristics must be prescribed to attain the desired results for the various communities considered. The challenge is to be able to control the prescribed fire within the constraints of smoke management concerns, shortened burning windows, and property ownership issues while limiting the negative environmental impact.
Repeated burning of the groundcover and the occurrence of deep‑burning turf fires can produce significant changes in the litter layer covering the ground and affect the associated community of soil arthropods, bryophytes, and lichens. Turf fires in wetlands during drought conditions also can remove layers of accumulated organic muck and significantly lower the elevation of the terrain. Finally, changes in the plant communities due to fire will also affect the animal communities that are associated with the vegetation types and habitats.
In the north, northern hardwood, white pine, Eastern hemlock, mixed oak and a variety of other species including isolated stands of red spruce are part of the forest composition. The oak/hickory type group is, and has been, the most common type forest in NJ. This group makes up nearly half of NJ’s forested area. This forest contains many mast producing species that provide important forage for wildlife.
While wildfires rarely attain the intensity as found in the Pine Barrens, northern NJ fires spread rapidly in dry leaf litter and downed, Gypsy Moth killed hardwoods. Slope becomes a significant factor in both the spread, and the difficulty in suppressing these fires. These higher intensity fires, or those fires that burn during drought conditions which consume the soil organic layers, can be damaging to the relatively thin barked trees. Adding to the intensity are the various species of rhododendron and laurel that are found on soils with a high iron content.
During the last century, the Phragmites reed grass replaced many of the native species along the state’s waterways and estuarine areas. Phragmites grow up to 14 feet high in fresh and brackish water, forming dense homogeneous stands that may occupy hundreds and even thousands of acres. Phragmites’ stalks begin to cure in the late fall and create highly flammable fuel loads exceeding 22 tons per acre. If a wildfire begins or spreads into a stand of Phragmites, it can be very difficult to extinguish due to the inaccessibility of the terrain. Flame lengths exceeding 50 feet are not uncommon in these extreme burning wildfire.