Archbold Biological Station
Biennial Report 1995-1996
P.O. Box 2057 Lake Placid, Florida 33862 USA
Phone: 863-465-2571 FAX: 863-699-1927
back to biennial 1995 home page
Conducted 20 burns at the Station and 5 burns at the Lake Placid Scrub Preserve, totalling over 1300 acres.
Conducted 2 interagency fire schools (taught U.S. Forest Service courses: S-190, S-130, and Standards for Survival) for 56 people.
Conducted 4 Station prescribed burn introduction courses for people who could not attend the interagency fire schools.
Kevin Main is a member of the Steering Committee for Central Florida Prescribed Fire Council and the Fire Committee of the Arbuckle Ecosystem Working Group.
Burn units and their fire-return intervals
Fire Management and the Fire Management Plan
Project Directors: Kevin N. Main, Land Manager and Eric S. Menges, Research Biologist
Before human settlement, Florida was a landscape molded by fire. Lightning-ignited fires burned across vast areas at regular intervals. They were stopped only by rainfall or natural barriers. Wetlands, such as bayheads and cypress strands, served as firebreaks in wet years, but during extended droughts provided accumulated fuels and muck soils that could burn for weeks. Areas burned frequently where fuels accumulated rapidly, such as in prairies, flatwoods, and sandhills. Other vegetation types, such as sand pine scrub and scrubby flatwoods, burned less often, acting as fire breaks until the right mix of weather and accumulated fuel loads allowed them to burn again. Variation in vegetation types, combined with variable weather patterns and drought conditions combined to create a landscape that was very patchy, at least with respect to fire. This patchiness provided the variety of habitats needed by Floridas wildlife.
Today lightning still strikes the land, but the land is no longer a vast wilderness that fire can burn across. Instead, it is a matrix of natural areas, pastures, citrus groves, cities, housing developments, and roads and highways. Since many human-modified areas act as barriers to the spread of fire, most isolated natural areas no longer burn at pre-settlement frequencies or scales.
Fire-management history. Several historical periods of fire management at the Station can be defined. Before settlement, fires were generally lightning-ignited and could burn across vast areas. Early settlers made the first attempts at fire suppression, but also ignited fires to serve their needs. The original Station property (1,050 acres) was acquired by John A. Roebling in 192930 and all fires were suppressed on this tract until 1985. The first prescribed fire conducted by Station personnel occurred in the West Sections in 1977. The use of prescribed fire accelerated during the 1980's, and in 199596, prescribed fire continues to be the primary habitat management tool.
The areas managed by Archbold Biological Station are now isolated natural areas, surrounded by citrus groves, pastures, and housing developments. Lightning-ignited fires on Station-managed properties are rare and must usually be confined to small areas to reduce the risk to adjacent landowners. Since we cannot rely on lightning-ignited fires to burn enough area to meet management goals, the Station uses prescribed burning to maintain its native habitats.
The Fire Management Plan (The Fire Plan) for Archbold Biological Station, extensively revised in 199596, guides decisions about where and when to burn [PDF file,103 pages]. The Fire Plan contains the framework for all Station activities related to fire and it attempts to balance diverse goals and to provide temporal and spatial heterogeneity across the landscape. The major goals of The Fire Plan are; maintain biological diversity, mimic natural processes, provide a diversity of research and educational opportunities, reduce fire hazards, and conduct safe burns. A mosaic of land units of various sizes, burned at various fire-return intervals, should satisfy these goals.
The Fire Plan is built around five fire-return intervals. Each interval is a range of years within which individual burn units are scheduled for burning (see map, page 23). A key element is the assignment of modal fire-return intervals to vegetation types (e.g. most sandhill habitats will burn every 25 years, most rosemary scrub will burn every 2059 years). Using fire-return intervals, rather than a fixed number of years, increases heterogeneity, provides research opportunities, and creates a plan with flexibility, including the ability to absorb most lightning-ignited fires. Heterogeneity is also provided by assigning units to intervals other than the modal one for the vegetation and by promoting variation in timing of fires, fire patchiness, fire intensity, and size of burns. Assigning fire return intervals to meet specific research needs, such as assigning a variety of fire return intervals to units containing critically-endangered species is useful for providing research-based management information.
The Fire Plan provides the framework for determining burn dates for individual burn units. Candidate burn units are selected based on the assigned fire return interval for each unit in relation to the time since the unit last burned. Initial burns in fire-suppressed areas (overdue for burning) are staggered to be burned over a time period corresponding to the modal fire return interval. Specific goals for burning vegetation types, overdue vs. maintenance burns, season of burn, research needs, and management and safety constraints are all factors used to further select or deselect units to be burned each year.
Planning and executing individual fires involves surveying units, preparing unit prescriptions, prioritizing which units to burn first, and preparing the units for burning. Unit prescriptions specify weather and drought conditions under which a unit may be burned, along with information on vegetation types, research needs, fire breaks, problem areas, and contingency plans. Priority of burning is based on several factors, including safety constraints, research need, narrow prescription window and species-specific needs (for example, waiting until all scrub-jays have fledged before burning a unit). Physical preparation to burn units include mowing road shoulders, disking firelanes, and felling snags close to unit boundaries.
Station fire policies are the rules governing all fire-related activities. Included are details on how to handle wildfires, fire crew training, personal safety equipment, and fire vehicle information. The wildfire guidelines provide a map of fire-sensitive areas and a specific set of instructions to follow in the case of an unplanned fire. Fire training is essential for conducting safe burns. Burn bosses must take training for State certification and all fire crew members must at least have entry level training. Mandatory personal safety equipment includes NOMEX fire clothing, hard hats with neck protectors, boots, and leather gloves. The policy provides specific directions for use of radios and fire vehicles.
The Fire Plans final section describes post-fire monitoring and research. After each fire, detailed fire-intensity maps are digitized onto the Stations GIS to provide a long-term historical database. Research following fires may or may not be burn-specific. Across the Station landscape a variety of times since fire and patchiness of individual fires provide scientists with a variety of opportunities for ecological studies related to fire effects and maintain biodiversity by mimicking what we understand about presettlement conditions.
Lohrer, F.E. (Editor). 1998.
Archbold Biological Station, Biennial Report 1995-1996. Archbold Biological Station, Lake
Placid. 62 pp.
© Archbold Biological Station, 1998 October.
Webmaster: Fred Lohrer, email: firstname.lastname@example.org