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5. Land and Resource Management Projects

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Fire Management Projects

SUMMARY OF DOI SCIENCE NEEDS RELATED TO FIRE MANAGEMENT PROJECTS
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DOI Lands Fire Management Plans

Project Purpose and Major DOI Interest
Fire Management Plan are a detailed program of action, which carries out established fire management policies and achieves fire goals and objectives in a safe and cost-effective manner. All DOI lands on which prescribed burning occurs must have an approved fire management plan. Everglades National Park was the first unit in the national park system to use fire to manage vegetation, and its fire management program remains a progressive institution, evolving with the body of knowledge about ecology and natural system management. In addition to ENP, LNWR, FPNWR, Florida Keys NWR, and J.N. Ding Darling NWR use fire for natural system management

Fire is and always has been an integral part of the development and maintenance of the Everglades. The pervasiveness of fire in the predrainage Everglades and its associated long-term ecological influence is evidenced by the common occurrence of charcoal fragments (fusinite) in soil core samples taken throughout South Florida. By the 1950s researchers were concluding that "the herbaceous everglades and the surrounding pinelands were born in fires" and that "enlightened administrative procedures will require a background of full information on all aspects of fire effects in the area." By the late 1960s and early 1970s ENP management was moving away from the "fire control plan" approach toward a more adaptive "fire management plan." In 1989 the recommendations of an Interagency Fire Management Team were adopted as NPS policy. Today, based upon historic and current research, it is clear that fire is an important natural ecological process and necessary in the preservation and conservation of ecosystems within Everglades National Park and on other DOI managed lands.

What Is Known
Fire has been one of the most influential and important ecological disturbances in the development and maintenance of ecosystems in South Florida. Fire was, and continues to be, important to the development and survival of many vegetative communities in the Everglades. Historically, fire preserved the dominance of sedges and grasses in short- and long-hydroperiod prairies by removing less fire-resistant species that might otherwise tend to gradually encroach upon them. Fire helped to clear areas of surface fuels, thus decreasing the potential for more severe, catastrophic fires. Fire aided in reducing live hardwood species in areas where softwoods, like South Florida slash pine, were dominant. Above all else, fire maintained the mosaic of species compositions and individual densities throughout the Everglades region.

Fire histories in ENP between 1948 and the 1950s are known to have inaccuracies; all fires ignited during this time period were typically recorded as "incendiary" or "human started" because local attitudes were that lightning did not ignite fires. Inadequate detection techniques from 1940-60 resulted in underestimation of lightning fire frequencies. Other than statistical work conducted with fire records and an analysis of various documented sources from 1910 forward, no comprehensive long-term fire history studies have occurred.

Perhaps the strongest biological evidence for relatively frequent fire occurrence prior to European arrival relates to the habitat requirements of some of the native plants. Documentation of the ecology and occurrence of more than 15 species of native herb species in the ENP pinelands in various long-term studies has shown that favorable conditions for these species rapidly decline as the fire-free interval (period of time when no fires occur) increases. Within a few decades of fire exclusion, pinelands turn into closed hardwood hammocks, which contain none or very few of the endemic herbs. More than 70% of the approximately one hundred herbaceous and low-shrub species native to southeast Florida occur in communities maintained by periodic fire.

The role of fire in the control of exotic plant species is generally understood for some species, including melaleuca and Brazilian pepper, but is not as clear for others, including Lygodium. Melaleuca is highly fire adapted. Melaleuca has a thick fire insulating bark and a high volatile oil content in its leaves, leading to high intensity fires. In areas where melaleuca is mixed with fire adapted native species, these high fire intensities typically result in the mortality of the native species. Melaleuca has serotinous capsules that are stimulated by fire to open and release seeds. Following a fire an average tree can release upwards of 10 million seeds on competition-free, nutrient-rich seed beds. This results in monotypic even-age stands of melaleuca that are commonly seen in natural areas of South Florida. Thus, fire should be excluded from areas containing mature melaleuca. Prescribed fire can be utilized post treatment to control seedlings. Melaleuca seedlings less than one meter in height are usually killed by fire, but this requires specific time of the burns and this procedure is not commonly used on NPS lands.

Fire can be a useful tool for controlling Brazilian pepper seedlings and saplings, but it provides very poor control of mature trees and no control in monotypic stands. In ENP, pine rockland areas are maintained largely free of Brazilian pepper through a five-year fire rotation; however, fire is not an effective control for mature trees.

Fire has been shown to reduce biomass accumulation and reduce herbicide needed to control Lygodium, although fire alone is not an effective control. Lygodium is fire tolerant and can cause natural/prescribed fires to spread into tree canopies of pine and cypress communities and kill canopy and subcanopy trees. Lygodium can also lead to the increased incident of spot fires. It is currently understood that cypress strands, hammocks, etc., should not be burned if Lygodium is present because trees may be injured or killed by burning Lygodium. The role of fire in Lygodium reproduction is not fully understood.

Though it is known that fire is a natural process and can help to improve habitat conditions care must be taken when using fire to ensure that it is not contributing to the water quality issues. Fire is known to alter soil nutrient concentrations with varying effects. Generally, the extent of the effects is related to the type of soils, vegetation present, and the type of fire. Surface fires in areas where soil moisture is relatively high and where only a portion of the above ground biomass is consumed may have little impact on soil nutrient status. More severe ground fires (peat fires) may result in the combustion of soil organic matter and a change in soil nutrient status making nutrients such as phosphorus more available to wetland vegetation. The exact relationships between fire, soil phosphorus, and water column total phosphorus are unknown.

What Is Needed
Research to determine prehistoric and predrainage fire frequencies and occurrences. An accurate fire history record for Everglades National Park and other DOI managed areas will require soil sample analysis as well as review of the records of historical human influences on fire. The historic documentation describes the occurrence of fire in an ecosystem that was increasingly altered by hydrologic changes. Little information exists about the natural fire ecology associated with predrainage hydrologic conditions.

Research to understand the links between hydrology and fire ecology. Additional paleoecological research is needed to evaluate the interrelationships between hydrologic and ecological processes and disturbance regimes, such as fire, in the predrainage Everglades.

Predictive models simulating ecological changes due to hydrologic restoration activities

Research on the tolerance of exotic species to fire and hydrologic change

Research to understand the link between the seasonal occurrence of fire and the life cycles of threatened and endangered species

Identification and monitoring of indicator species

Monitoring and research to understand the links between fire and water quality


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