Non-alluvial wetlands dominated by pond cypress (Taxodium distichum var. nutans) including Cypress ponds, cypress strands, cypress domes, sinkhole ponds, cypress-gum ponds and cypress savannahs are a common feature of the southeastern coastal plain. These wetlands tend to be isolated, situated within a matrix of fire-adapted communities. Rain, runoff and shallow groundwater are the dominant sources of water in most of these pond cypress wetlands. Water levels fluctuate widely, and hydroperiods are long ranging from 6 to 12 months per year. The soils of these communities range from organic and peat accumulations to mineral soils.

The vegetation of these cypress-dominated wetlands differs in composition and structure. The canopy can be almost purely pond cypress in cypress savannahs to mixtures of cypress, pine and hardwoods in other cypress wetlands. Shrubs may dominate midstories or shrubs may be absent. Herbs can be common, where shrubs are absent and where standing water is not too deep. Wetland margins are habitat for many rare plants.

Animals that use pond cypress wetlands include a diverse assemblage of invertebrates. Fish populations are not well developed in cypress wetlands that are ephemeral. However, amphibians and reptiles take advantage of the ephemeral nature of the wetlands and are common and important components of cypress wetland fauna. Several listed species of amphibians use cypress wetlands for breeding. Bird fauna is dominated by passerines. Mammal species found in these cypress systems tends to be similar to those that use the surrounding communities.

The fire regime of isolated wetlands is influenced by the surrounding fire adapted communities. Historically, the margins of these isolated wetlands may have experienced a higher fire frequently than the centers of wetlands as fires spread from upland into wetlands. Wetland margins may have burned as often as every 3 years and entire wetlands may have gone as long as 10 to 100 years depending on the frequency of drought and draw down. Natural fires are thought to have occurred in early lightning season and coincided with a time of common drawdown of wetlands. Human alterations of the natural fire regime include decreases in frequency of burns in wetlands and shifts from the natural lightning season to dormant season burns. Further, wetlands have often been “protected” from fire by plowed fire lines.

Fire helps shape the vegetation of pond cypress communities. Pond cypress is resistant to fires and will survive fires that hardwoods do not. Pond cypress is known to sprout following injury from fires. However, severe ground fires will cause mortality of pond cypress. Fire and hydrology are instrumental in limiting hardwood invasion of pond cypress wetlands. Little research has been conducted on fire effects on shrubs in cypress wetlands; however, shrub response is likely similar to shrubs of other wetland and pine systems with frequent fires helping to limit shrub invasion. Frequent fires are important in maintaining herbaceous ecotones and herbs in some wetlands.

Animal species are influenced by fire through the effects on plants. Infrequent fires resulting in canopy closure decrease use by wading birds, amphibians and reptiles. Grassy ecotones are particularly important for reproduction of several listed amphibian species including the flatwoods salamander, striped newt and gopher frog.

Prescribed fire programs have often excluded fire from pond cypress wetlands through the use of plowed firebreaks and by burning under wet conditions. Smoke management and fire control may be an issue when burning cypress wetlands with organic soils. Allowing fires to burn into and through wetlands is ecologically desirable because of the effects of fire on vegetation and the effect of vegetation on animal habitat, including listed species habitat. However, the conditions under which vegetation within cypress stands will burn and any organic soil will not, are precise. Prescriptions that include such goals may create narrow burn windows.

Cypress ponds and related communities, cypress strands, cypress domes, sinkhole ponds, cypress-gum ponds and cypress savannahs, are all non-alluvial wetlands, dominated by pond cypress (Taxodium distichum var. nutans). These wetlands are a common feature of the southeastern costal plain occurring in Florida, Georgia, South Carolina, North Carolina, Alabama, Mississippi, into southeastern Louisiana and as far north as southeastern Virginia (Ewel 1995). These wetlands range widely in size from less than 1 ha (0.25 acres) to greater than 10 ha (25 acres) (Ewel 1998, Schalles et al. 1989), but within the landscape, small wetlands are much more common than are large wetlands (Schalles et al. 1989, Semlitsch and Bodie 1998). These wetlands are situated in basins or depressions and generally have no connection to aboveground streams or river systems (Russell et al. 2002). Fire plays an important role in shaping these communities (see Fire Regime).

Rainfall patterns and thus hydrology differ among these wetlands within their range. In south Florida, there tends to be distinct wet and dry seasons (Wade et al. 1980). In northern Florida and southern Georgia there tends to be two wet seasons, one in winter, associated with passing cold fronts and another in summer due to convective storms (Chen and Gerber 1990). Farther north and west in the costal plain, rainfall tends to be more evenly distributed throughout the year (Kirkman et al. 2000).

Rain, runoff and shallow groundwater are the dominant sources of water in pond cypress wetlands, with the exception of sinkhole ponds, which are sometimes connected to deeper aquifers (Ewel 1990, 1998). All of these wetlands are subject to widely fluctuating water levels, which are often unpredictable. Water fluctuation is important in these wetlands as cypress requires dry ground for germination (Demaree 1932) and under non-flooded conditions hardwoods out-compete cypress (Marios and Ewel 1983). Hydroperiod in these wetlands ranges from 6 – 9 months per year for cypress domes and savannahs (Marios and Ewel 1983, FNAI 1990, Sutter and Kral 1994) to 6-12 months for pond cypress ponds and cypress gum ponds (Sutter and Kral 1994). Basin depth (water plus accumulated peat) is typically shallow, < 1.5m (Casey 1997) and water is acidic (Brown 1981).

Cypress domes are thus named because of their domed appearance with tallest trees at the center and shortest vegetation at the edges. Of the pond cypress dominated communities, cypress domes and strands are most likely to contain peat deposits, though peat is not always present. Where peat or surface organic soil layers are present, they are deepest in the center of the wetland. Some domes contain non-forested areas of nearly permanent standing water in the deepest center portions of the dome. This community type is most common in Florida and southern Georgia. Cypress strands, also most common in Florida, particularly in south Florida, are shallow depressions in close proximity to one another that coalesce and contain flowing water in times of flood. Strands can be hard to distinguish from cypress domes under conditions of low water. The deepest portions of strands that often contain flowing water can have bald cypress present (Ewel 1990). Cypress ponds and cypress gum ponds are most common from the panhandle of Florida northward. They occur in shallow depressions but tend to be characterized by mineral soils or organic soils rather than peat and can occur in Carolina Bays, a type of depression of uncertain geologic origin, lime sinks or in other depressions. Cypress savannahs occur in broad basins with mineral soils underlain by clay (Schafale and Weakley 1990). A variant, dwarf cypress savanna occurs over very shallow, nutrient poor soils underlain by limestone in south Florida (Wade et al. 1980). Dwarf cypress also occurs in the Panhandle of Florida (Ewel 1998).

There tends to be a gradient of nutrient availability that is mirrored by productivity ranging from low productivity in dwarf cypress savannahs to intermediate in cypress domes to moderate in cypress strands (Brandt and Ewel 1989).

Vegetation:

Pond cypress dominated wetlands differ from bald cypress (Taxodium distichum) dominated communities, which occur along river drainages and lake margins not only in fire frequency, but also in hydrology, productivity, nutrient availability, and species richness. Bald cypress tends to occur where there is flowing water whereas pond cypress occurs in still water wetlands. Nutrient availability, productivity and species richness all tend to be higher in bald cypress swamps as opposed to pond cypress swamps (Ewel 1995). Fire frequencies are higher in pond cypress wetlands (see Fire regime)

Common vegetation in cypress domes and strands includes pond cypress, swamp tupelo (Nyssa sylvatica var. biflora), and slash pine (Pinus elliottii) in the canopy. Other canopy species can overlap with those of bay swamps. Midstory can be lacking, sparse or comprised of shrubs including fetterbush (Lyonia lucida), Virginia willow (Itea virginica), button bush (Cephalanthus occidentalis), titi (Cyrilla racemiflora), and dahoon holly (Ilex cassine). Common vines include laurel greenbrier (Smilax laurifolia) and poison ivy (Toxicodendron radicans). Where shrubs are absent or sparse, groundcover can include sphagnum and various sedges (Ewel 1990, FNAI 1990).

Farther north, cypress-gum pond canopy species include pond cypress, swamp tupelo. Shrub species are sparse except around pond margins and can include storax (Styrax americana) hurrah-bush (Leucothoe racemosa) sweet pepperbush (Clethra alnifolia) and fetterbush. Sedges and canopy species seedlings sparsely cover the ground layer (Kirkman et al. 2000).

Pond cypress is the dominant canopy species in more northerly cypress savannahs and is widely spaced over a grass and herb dominated understory. Other trees can occur in the canopy including swamp tupelo, persimmon (Diospyros virginiana) and red maple (Acer rubrum). The most common shrubs include myrtle leaf holly (Ilex myrtifolia) and buttonbush. The herbaceous groundcover is diverse and variable among sites and dominant species can change dramatically from year to year within a site (Sutter and Kral 1994, Schafale and Weakley 1990). Sutter and Kral (1994) suggest that these cypress savannahs are among the most floristically diverse systems in the southeastern costal plain.

In South Florida, dwarf cypress savannah is dominated by stunted pond cypress with grasses, sedges and forbs in the understory. Cover of the understory can be quite sparse to continuous depending on the qualities of soils and overstory density (Wade et al. 1980).

Animals

There is generally a high diversity of invertebrates in cypress wetlands in comparison to other systems (McMahan and Davis 1984). Among invertebrates, bottom-dwelling species involved in decomposition likely form the base of wetland food chains (Ewel 1998). The most common small invertebrate taxa represented in dome systems in Florida included flies; ants, wasps and bees; spiders and bugs (McMahan and Davis 1984). Crayfish are also common inhabitants of these systems (Ewel 1990, Hart and Newman 1995).

The ephemeral nature of most pond cypress wetlands tends to prohibit the development of an extensive fish fauna, although fish populations can be important in wetlands with permanent or semi-permanent water (Ewel 1990, Hart and Newman 1995). Presence/absence of fish is related to the period of flooding and the proximity of the wetland to permanent wetlands from which fish emigrate during floods (Snodgrass et al. 1996, Hart and Newman 1995).

A particularly important component of these small, isolated, temporary ponds are amphibians and reptiles (Semlitsch and Bodie 1998, Russell et al. 2002). The general lack of predatory fish creates an environment important for amphibian breeding and larval development. Reptiles utilize these wetlands for cover, foraging and hibernation (Russel et al. 2002). High diversity and densities of amphibians and reptiles using small isolated wetlands have been documented all over the Southeastern Costal plain. Russel et al. (2002) documented 26 species of amphibians and 36 species of reptiles utilizing wetlands. Similar numbers of reptile and amphibian species have been found in other isolated wetlands in the southeastern costal plain (Harris and Vickers 1984, reviewed in Semlitch and Bodie 1998, and Russel et al. 2002). Frogs and toads are particularly numerous (Harris and Vickers 1984). Various species of salamanders also utilize these wetlands including the federally threatened flatwoods salamander and the striped newt, a candidate for listing.

Bird life tends to be dominated by passerines, including many migrants, and cavity nesting birds. Common species include common yellow throat warbler, robins, woodpeckers, Carolina wrens and occasionally wood ducks (Workman 1996, Harris and Vickers 1984). These birds tend to forage for insects in evergreen vegetation and some take advantage of fruits produced by various shrubs and vines. Wading and water birds are not common in shrubby cypress systems, but are known from systems with open understories, and will utilize clear-cut systems (Harris and Vickers 1984, Workman 1996). Cypress wetlands in Florida are known to contain wading bird rookeries (Ewel 1998)

Use of pond cypress wetlands by mammals is not as frequent or intensive as in other nearby systems (Harris and Vickers 1984), and there are no mammals that are restricted to or endemic in these wetlands (Ewel 1998, Schalles et al. 1989). Small mammals that use these wetlands tend to utilize the periphery or ecotone of the wetland (Harris and Vickers 1984). Various species of mice and rats, shrews, otters, possums, raccoons, mink and white tailed deer utilize wetlands (Hart and Newman 1995). These wetlands may be important sources of food and cover for some species of mammals (Hart and Newman 1995).

Wetlands are important habitat for numerous rare plant species (Edwards and Weakley 2001, Harper et al. 1998, Robertson et al. 1998, Chafin 2000, Walker 1993). Among rare plant species associated with longleaf pine ecosystems, rare species were much more likely to be found in wet habitats than dry (Walker 1993). Numerous rare species utilize ecotones (Edwards and Weakley 2001, Harper et al. 1998, Robertson et al. 1998, Chafin 2000, Walker 1993). Of rare species associated with longleaf pine systems or with non-peat wetlands, most rare species were non-woody plants (Walker 1993, Edwards and Weakley 2001).

Thus, an important management concern is the maintenance of wetland ecotones as habitat for rare plant species. Fire management programs have often negatively affected forested wetland ecotones by placing fire lines there and “protecting” wetlands from fire. Alterations of the natural fire regime have also negatively affected rare plant habitat.

Species that utilize ecotones of forested wetlands are maintained by a combination of soils, hydrologic conditions and frequent fire. Frequent fire maintains the herbaceous ecotone, by controlling the distribution of shrubs which shade and out-compete many herbs (Drewa et al. 2002a, 2002b).

Several forested wetland types have these ecotones, often herbaceous, that support rare species including, cypress wetlands, shrub bogs, pond pine woodlands associated with pocosins (sometimes considered a type of pocosin), seepage slopes, and bay forests.

The following are a selection of rare species that are Federally listed as threatened, endangered, candidates for listing or species of Federal management concern associated with these wetlands and ecotones. Numerous other species that utilize forested wetlands and/or their ecotones are tracked by State Heritage programs and states. Each of these plant species may also utilize habitats other than forested wetlands. For a tabular representation of wetland rare plants occurring on military installations and their habitats see Harper et al. (1998) and Robertson et al. (1998). For more information on Southeastern rare plants tracked by States or State Heritage programs see:

• The Florida Natural Areas Inventory Field Guide to Rare Plants and Animals or
• Endangered, Threatened, & Rare Plant Species of the Southeastern United States.

Pond Cypress Wetlands

Two Federally listed species restricted to the Florida Panhandle, threatened Godfrey’s butterwort (Pinguicula ionantha) and endangered Florida scullcap (Scutellaria floridana) are known from cypress wetland margins. Both of these species are dependent on fires (Chafin 2000, USFWS 1992, 1993). Godfrey’s butterwort does not tolerate shading from shrub encroachment and Florida scullcap requires fire to maintain vigorous growth (USFWS 1992, 1993). Canby’s dropwort (Oxypolis canbyi), a federally endangered plant, is also dependant on fires. A population was observed to increase after fire and may depend on fires to maintain an open environment (Hessl and Spackman 1996). Another species of Federal management concern, Lobelia boykinii depends on fires to keep canopies open to provide sufficient light for growth, particularly in drier wetlands where the hydroperiod is too short to prevent hardwood encroachment. Further, fire is important for removing leaf litter, a requirement for plant germination (Lacy et al. 2001). See also: Fire Ecology and Management of Pond Cypress Wetlands.

Shrub Bogs

Federally listed plants associated with streamhead shrub bogs include the endangered rough leaved loosestrife (Lysimachia asperulifolia). Loostrife is shade intolerant and is dependent on frequent fires to eliminate shrub competition (USFWS 1987, Robertson et al. 1998). Several other species that are narrowly distributed and occur only in the panhandle of Florida are also associated with streamhead shrub bogs including the Florida skullcap (see above), Chapman’s rhododendron (Rhododendron chapmanii), Panhandle lily (Lilium iridollae) and Harpers beauty (Harperocallis flava). Chapman’s rhododendron, a woody plant, requires fire to eliminate better shrub competitors and to stimulate flowering and new vegetative growth (Chafin 2000, USFWS 1979). The herbaceous species require fires to control competing shrubs. Numerous other species of federal management concern or candidates for federal listing also use these transition zones including Carolina goldenrod (Solidago pulchra), Carolina asphodel (Tofieldia glabra), bog spicebush (Lindera subcoriacea), venus flytrap (Dionaea muscipula) and the formerly listed white wicky (Kalmia cuneata) (Robertson et al. 1998, Chafin 2000, Hart and Newman 1995, Harper et al. 1998). Fire is thought to stimulate the flowering and vegetative growth of white wicky (USFWS 2000). See also: Fire Ecology and Management of Shrub Bogs.

Pond Pine Woodlands and Pocosins

Rough leaved loosetrife is known from pocosin margins (see above). See also: Fire Ecology and Management of Pond Pine and Fire Ecology and Management of Pocosins.

There is widespread recognition that cypress dominated forests are tied to fire (citations in Ewel and Mitsch 1978 and Wade et al. 1980). Because these systems are isolated wetlands within a matrix of other fire adapted community types such as pine flatwoods, wet prairies, pine savannahs or marshes, fires periodically spread from the upland pyric communities into wetlands especially in the dry season (Ewel and Mitsch 1978, Kirkman 1995). Fire frequencies in these isolated, pond cypress dominated wetlands appear to be on the order of decades (every 10-50 years) rather than centuries as for bald cypress dominated wetlands (Ewel 1990).

Different types of pond cypress wetlands and different portions of wetlands likely experienced different fire frequencies. The actual historical frequency of fires in these systems is not well understood. The frequency of fire is likely inversely related to the length of hydroperiod and depth of flooding in the wet season (Ewel 1998, Kirkman et al. 2000). Historically, the margins of these isolated wetlands may have experienced a higher fire frequency than the entire wetland as fires from the uplands spread down into wetlands before reaching non-flammable vegetation or saturated soils (FNAI 1990). For dome swamps the outer edge may have burned as frequently as the surrounding natural community (every 3-5 yrs; FNAI 1990), where the centers of domes, especially large domes, may have burned only every 100-150 years (FNAI 1990). A frequency of one burn in 20+ years is cited for domes by Sutter and Kral (1994). Cypress ponds and cypress gum ponds with mineral or organic soils burned infrequently, every 20 to 50 years (Sutter and Kral 1994). Cypress savannahs likely burned more frequently than domes, once per decade (Wade et al. 1980). Cypress strands are thought to have burned less frequently than domes (Wade et al. 1980). In the absence of fire, hardwoods out compete cypress and cypress dominated wetlands are thought to succeed to hardwood swamps (Ewel 1998, literature cited therein). Shrub invasion has been documented where dome hydrology was altered due to ditching and where fires were excluded (Marois and Ewel 1983).

The natural fire season of cypress wetlands was likely the early lightning season, before the onset of the summer rainy season when wetlands were likely to be dry, increasing the probability that they would burn with the surrounding communities (Robertson et al. 1998).

Pond cypress wetlands with extensive peat accumulation (i.e., deeper basins) may be susceptible to infrequent, severe ground fires. These fires can consume soil killing much or all of the vegetation rooted therein. Drained cypress domes and strands are likely at a greater risk of severe ground fires (Marios and Ewel 1983). Observations suggest that severely burned cypress domes and strands are invaded by shrubs such as Carolina willow (Salix caroliniana) in south Florida (Wade et al. 1980), tupelo and titi farther north (Ewel 1995, Marios and Ewel 1983) or may become herbaceous wetlands or aquatic sites such as the open water at the center of cypress domes. This process of severe fire during drought is important in maintaining characteristics of Carolina Bays (a wetland of specific geologic origin, in which pond cypress can occur) (Schalles et al. 1989).

Anthropogenic Alterations of the Fire Regime

Fire is rarely applied directly to forested wetlands, aside from silvicultural applications (Brandt and Ewel 1989). Much of the surrounding habitats have routinely been prescribe burned in the dormant season. This shift in season of burn for surrounding communities, i.e., burning in the dormant season as opposed to the natural lightning season, has likely inadvertently lead to a decrease in fire frequencies within cypress wetlands. Wetlands typically hold more water in winter, thus are less likely to carry fire in winter than in droughty spring periods (Kirkman et al. 2000). In addition, many wetlands are “protected” from fire by plowed firebreaks (Kirkman et al. 2000).

Vegetation

Surface fires typically leave cypress unharmed (citations in Wade et al. 1980), especially where cypress can root at least partially in mineral soil or where peat soils do not ignite (Ewel and Mitsch 1978). Bald cypress is known to be very tolerant of fire with only longleaf pine, slash pine and loblolly being more tolerant given similar bark thickness (Hare 1965). Though fire tolerance of pond cypress was not systematically compared with bald cypress, the bark of pond cypress tends to be thicker and shaggier than that of bald cypress suggesting that it may be even more fire tolerant than bald cypress (Ewel 1998). Cypress is known to sprout epicormically when branches are killed by fire and coppice following cutting and burning where above ground stems were killed (Ewel and Mitsch 1978). Cypress coppice, however, are often killed by fire (Ewel 1995).

Severe ground fires can kill mature cypress trees particularly when growing on deep peat (Ewel and Mitsch 1978). If cypress is not killed by a severe ground fire, the tree can be wounded leading to fungal infection and heart rot (Ewel 1995). Heart rot may contribute to tree cavity development. Furthermore, some ground fires that do not cause direct mortality may contribute to secondary mortality from windthrow by consuming soil and roots that function to anchor trees.

There is some suggestion that fires may stimulate cone production in cypress, but further investigation is needed to confirm this (Ewel 1995).

A combination of fires and hydrologic regimes limits hardwoods within cypress wetlands. Hardwoods are generally recognized as being less tolerant of fire than cypress (Hare 1965). In one study, hardwoods suffered more mortality than cypress after a wild fire (Ewel and Mitsch 1978). This suggests that frequent fires play a role in limiting hardwoods within pond cypress wetlands.

Little research has been done specifically on the effects of fire frequency or season on shrubs in cypress wetlands. The role of fire frequency, season and intensity in controlling hardwoods and shrubs in upland systems is relatively well studied. In general, very frequent fires (annual) in the growing season are most effective at reducing hardwoods and shrubs in upland systems. Many of the shrubs and hardwoods studied in various upland systems such as flatwoods and pine savannahs are the same shrubs that occur in pond cypress wetlands. In addition, observations of fire practitioners suggest that frequent fires may be important in reducing shrubs in wetlands. For instance, Ferguson (1998) observed that growing season fires applied in the Apalachicola National Forest had the effect of reducing titi (Cyrilla racemiflora, Cyrilla parviflora and Cliftonia monophylla) and opening the transitions to wetlands. In examining aerial photography, Huffman and Blanchard (1991) observed that woody plants invaded wetlands after a period of fire suppression, and after reintroducing fires under droughty conditions, noted that hardwoods appeared to decrease. Literature on herbaceous bogs also suggests that frequent fire maintains them as such and the absence of fire promotes shrubby systems (reviewed in Harper et al. 1998). However, recent studies in shrub bogs and marshes suggests that fires do not decrease shrub density, but frequent fires can eliminate recruitment into new areas and thus maintaining shrub free zones (Olsen and Platt 1995, Drewa et al. 2002a, 2002b) and frequent or lightning season fires may decrease the cover of shrubs (Lee et al. in press, Lee et al. In prep)

Similar to upland systems, the abundance of herbaceous plants including many rare plants is dependent on fire regime. An open canopy in cypress domes has been correlated with greater abundance of grasses and sedges (Marios and Ewel 1983). Fire with the hydrologic regime are important in keeping canopies open and limiting shrub layers of cypress wetlands thus eliminating competition for herbaceous species. The number of rare plant species found there demonstrates the importance of fire in maintaining an herbaceous wetland margin. 

The process of frequent fire may have been important in limiting organic soil buildup and peat accumulation, especially in more shallow wetlands by removing plant debris that would otherwise accumulate as peat (Kirkman et al. 2000, Schalles et al. 1989).

Animals

There has been little study of the direct effects of fire on wildlife inhabiting domes; however, a growing body of literature is beginning to implicate the indirect effects of fire suppression on vegetation in and around wetlands in declines and changes animal populations, particularly amphibian populations (Russell et al. 2002).

Canopy closure due to invading hardwoods and an increase in shrub dominance in the absence of fire (see plant response) affects animal species composition and abundance. Wading birds appear to prefer permanent water, large diameter trees, sparse hardwoods and an open understory (Harris and Vickers 1984). Several amphibian species including the pig frog, striped newt and flatwoods salamander utilize seasonally flooded grassy ecotones for foraging or breeding (Hart and Newman 1995, Palis 1996, Franz and Smith 1999). Canopy closure of wetlands historically used by the federally endangered Mississippi gopher frog is one of the factors cited in many wetlands becoming unsuitable breeding sites (USFWS 2001). Canopy closure in wetlands has decreased the abundance of some species of amphibians and has been correlated with extinctions of others (Werner and Glennemeier 1999, Skelly et al. 1999).

Several Federally listed amphibians such as the flatwoods salamander and the Mississippi gopher frog; a candidate for listing, the striped newt; and regionally rare species such as the Dusky gopher frog and the Florida gopher frog utilize habitats maintained by frequent fires. All species utilize upland habitats in stages of their life cycles, but breed in small, ephemeral wetlands including cypress dominated wetlands (Johnson 2000, Palis 1996, Franz and Smith 1999). Habitat loss due to modification by agriculture, forestry operations or other uses is the largest threat cited for all species. However, where suitable habitat remains, much of it has been degraded by fire suppression in both uplands and wetlands (Palis 1996, USFWS 1999, USFWS 2001, Johnson 2000, Franz and Smith 1999).

The role of frequent fire in maintaining herbaceous plants is particularly important for these amphibian species. Grassy wetlands, with an open canopy are critical for flatwoods salamander and gopher frog reproduction. Gopher frogs use emergent vegetation for deposition of eggs and larval flatwoods salamanders utilize herbaceous vegetation for cover and for foraging (USFWS 2001, Palis 1996). Maintenance of the grassy nature of the wetland particularly the ecotone requires frequent early lightning season fires to prevent shrub invasion (USFWS 2001). Less is known of the biology of the striped newt; however, it tends to persist only in frequently burned habitats (Johnson 2001). It appears that herbaceous vegetation in wetlands and uplands is important in this species’ life cycle. Placement of firebreaks around wetlands can lead to detrimental changes in these species habitats.

A decrease in fire frequency, nearly to the point of excluding fire from cypress wetlands has been the outcome of many prescribed fire programs. Many wetlands have historically been protected from fire by plowing fire lines around the wetland (Frost, Walker and Peet 1986). Recently though, the importance of fire to the ecology of these wetlands and the detrimental effects of fire lines that “protect” these wetlands has been recognized. The practice of protecting wetlands from fires stems from the misconception that forested wetlands shouldn’t burn and from the practical concerns of smoke management and fire control.

When implementing a prescribed fire program in cypress wetlands a number of issues should be considered:

1. For the maintenance of the natural community must be balanced with practical limitations in burning. Examination of wetlands to determine the risk of ground fires, i.e., how much organic soil or peat is actually present, and the water content of peat throughout the soil profile are important considerations. If peat is not present there is effectively no risk of a severe ground fire and using fire in these wetlands may help prevent the formation of organic soil layers (Kirkman et al. 2000). However, accumulated litter, though it is not technically peat can create similar challenges. An alternative method of keeping fires out of wetlands includes using mowed breaks.
2. Burn as often as surrounding communities and in the growing season (every 2-5 years where flatwoods or pine savannah is the surrounding community). The likelihood of Cypress wetlands burning is dependent on the moisture levels in the wetland, which tend to vary seasonally. Dormant season fires, often the norm, coincide with periods when cypress wetlands hold relatively more water, thus are less likely to burn. Conversely, wetlands often experience drawdown in spring, precisely when lightning season fires were historically most common (Kirkman et al. 2000). From an operational standpoint, the precise moisture condition required for fire to carry through these wetlands without igniting accumulated organic matter, are rare and make it challenging for fire managers to provide fire within these communities. This is further complicated because, since fire typically enters these communities from burns in the adjacent uplands, conditions dry enough to burn the cypress communities can be too dry for desirable results from a prescribed burn in adjacent uplands.
3. In cypress wetlands that have been altered through fire suppression or drainage, consideration should be given to reducing fuel loads with dormant season burns before reintroducing growing season fires. The dense shrubby midstory that often surrounds fire-suppressed cypress swamps, including species like titi, fetterbush or gallberry, may not carry a backing fire under weather conditions commonly prescribed for a burn. This effect is more pronounced in the dormant season. If the area is consistently burned with the same wind direction, a pronounced fire shadow may be left even after several prescribed fires. This dense midstory may be top-killed by burning on a variety of wind directions, altering firing techniques (strip head fires, head-firing the swamp from the inside out, etc), by introducing growing season burns, or by mowing. Fire lines, canals, and beds in wetlands or their ecotones should be rehabilitated to restore hydrology and to facilitate fire spread. Where this is not feasible, the firing technique can be altered to carry fire over barriers that prevent fire spread. Fire spread into wetlands may be hindered by the orientation of features such as beds relative to the direction of fire spread (i.e., under wet conditions fires may only spread in the direction of beds unless shrub midstories carry fire).
4. Listed species are known to occur, life histories of known species should be considered when implementing a fire program.

Fire managers have a history of protecting forested wetlands from fire. Wetlands commonly “protected” from fire include pond cypress wetlands, streamhead and small basin shrub bogs, swamps, and isolated bay forests. The effects of fire suppression due to fire lines have repercussions in plant communities notably increases in woody plant dominance and canopy closure. These changes in turn affect plant and animal communities. Changes in hydrology caused by fire lines have also been implicated in changes in plant and animal communities.

Vegetation Structure and Composition

Ecotones of wetlands are often where fire lines are constructed and where many of the detrimental effects of fire lines are seen. The ecotone of many forested wetlands has a zone that is herb dominated, likely maintained by a combination of hydrologic conditions and frequent fire (Robertson et al. 1998). Construction of fire lines in the ecotone can lead to the elimination of this herb-dominated zone. Where fire is excluded in areas down slope from fire lines, shrubs invade. Shrubs often out compete herbs, thus eliminating the herbaceous ecotone between forested wetlands and surrounding fire maintained communities. Subsequent fire lines are often constructed up slope from the last thus exacerbating the shrub expansion problem (Frost, Walker and Peet 1986).

Wetland ecotones are noted as the habitat for a number of rare plant species (Harper et al 1998, Hart and Newman 1995, Robertson et al.1998, Chafin 2000, Edwards and Weakley 2001). Many of these rare plants utilizing these habitats are non-woody (Walker 1993, Edwards and Weakley 2001). Invasion of shrubs into these ecotones threatens these rare non –woody plants that tend to decrease in abundance as shrubs increase (Harcombe et al. 1993, Peet and Allard 1993). Plowing lines in this zone can also physically destroy some of these plants (Frost, Walker and Peet 1986).

Several rare amphibian species including the flatwoods salamander, striped newt, gopher frog and Pine Barrens tree frog, are also depend on herbaceous wetland ecotones for completion of their life cycle (Palis 1996, USFWS 1999, Harper et al. 1998). Changes in habitat structure (i.e., elimination of open herb and grass dominated areas) due to fire suppression are implicated in the degradation of gopher frog and flatwoods salamander breeding sites (USFWS 1999). Pine barrens tree frogs also utilize the interface between shrubby areas and open pools (Harper et al. 1998). (See: Fire Ecology of Pond Cypress Wetlands)

Hydrology

In addition to changes in vegetation structure, plowed lines can change hydrology of isolated wetlands (Bacchus 1995).

• Plowed lines can make connections to adjacent permanent water wetlands (Harper et al. 1998)
• They can alter hydroperiod (Palis 1996).
• Fire lines have been implicated in altering seepage hydrology by channeling water away from the site (Bacchus 1995, Hermann 1995).
• Erosion can also become a problem where fire lines are constructed in wetlands with topographic change such as streamheads (Robertson et al. 1998, FNAI 1990, Frost Walker and Peet 1986).

Some of effects of theses hydrologic changes are as follows:

• Hydrologic changes to wetlands are known as causes of floral and faunal changes in wetlands (Ewel 1990, Harris and Vickers 1984).
• Direct effects of fire line construction include plowed lines ponding water, which amphibians use as breeding sites. These sites are often unsuitable because they are isolated and falling water levels strand and kill amphibians in the aquatic phase of their lifecycle (Harper et al. 1998).
• Fire lines that connect isolated wetlands to permanent water bodies can allow colonization by predatory fish. This process is detrimental to amphibian populations whose larval stages can then fall prey to predatory fish (Palis 1996).

Management Guidelines

Fire is important in forested wetlands for maintenance of vegetation structure and composition and for maintaining plant and animal habitat. Fire managers have created firebreaks in wetland ecotones in part to widen the hydrologic window under which adjacent communities can be burned (excluding wetlands due to risk of ground fire). Some managers feel that hard firebreaks separating wetlands are necessary to meet management targets with respect to burn season, frequency and fire effects in the surrounding natural communities. The negative ecological effects of plowed fire lines should be weighed with operational needs.

The following guidelines should be considered in management of forested wetlands embedded within fire type communities:

• Do not place plowed lines in ecotones.
• Allow fire to burn through wetlands or allow fire to penetrate into wetlands.
• Determine the necessity of protecting wetlands:
  • Is organic soil actually present?
  • Under what moisture regime and organic matter content might soils ignite?
  • Is it possible to allow organic soils to ignite from smoke management, containment, and legal perspectives? Many local and state governments have implemented laws and rules that effectively prohibit smoldering ground fires (see organic soils).
• Utilize alternatives to plowed lines when not allowing fires into wetlands.
• Burn under conditions of high moisture when wetlands are not likely to burn.
• Utilize mowed breaks rather than plowed lines.

Organic soils are often, though not always, present in some types of forested wetlands and in some herbaceous wetlands. Long hydroperiods are often associated with organic matter accumulation (Kirkman et al. 2000, Ewel 1990, Kushlan 1990). Deep duff and organic surface horizons can also develop in some sites after long fire-free periods.

Fire practitioners are often wary of burning wetlands with organic soils. The problems are twofold:

1. Organic soils will ignite under certain conditions resulting in often long lasting, smoldering fires that produce copious amounts of smoke.
2. Long lasting, smoldering fires are difficult to extinguish, can be sources of ignition causing reburn or escapes and thus present control problems.

These two problems can result in violation of state or local laws that regulate open burning (Ex: Florida Statute 590). Rules and laws that govern air pollution and visibility, and requirements for extinguishing fires within certain time frames may be violated when hard to extinguish and smoke producing ground fires are ignited. (For more information and examples of State level open burning statutes please visit The Nature Conservancy Information Resource Center).

If a fire starts in organic soils, it may burn for months and typically will continue to burn until one of the following conditions occurs:

1. Organic soils burn down to mineral soil and the fire runs out of fuel.
2. Significant rain occurs which either raises the water table until it reaches the fire or moisture content of the organic soils reaches the moisture of extinction.
3. Intensive suppression efforts isolate and then suppress the burning organics. Suppression typically requires a fireline constructed to mineral soil to isolate the burning area, followed by copious amounts of water applied to the burning area. The ecological harm resulting from this type of suppression is extensive. These suppression efforts are also extremely expensive, costing thousands of dollars per acre.

There has historically been a considerable amount of uncertainty in knowing under what conditions fires in organic soils would ignite. A large range of values of minimum moisture content for safely burning sites with organic soils has been reported in the literature (reviewed in Hungerford et al.1996). However, recent research has helped to clarify factors contributing to organic soil ignition. The probability of igniting a ground fire varies with the amount of organic matter in the soil and the moisture content of the soil (Hungerford et al. 1996). Soils with higher levels of organic matter will ignite at lower temperatures than soils with lower levels of organic matter given the same moisture content. And given the same organic matter content moister soils are less likely to ignite than drier soils. Hungerford et al. (1996) have quantified this relationship (see graph). The moisture content of hummocks also plays a role in initiation of ground fires (Hungerford et al.1996). An understanding of these factors is necessary when planning a fire that may result in whether or not to ignite ground fires.

While there is long term ecological benefit from the periodic burning of these organic soils, the immediate smoke production, control difficulties, and unpredictability of these fires makes burning the organic soil impracticable for all but a few locations. In most situations, smoke management and fire control requirements compel managers to avoid igniting organic soils and to extinguish them where they do occur.

When managers are faced with burning areas that include organic soils several factors should be considered.

• Probability of igniting a ground fire (percent organic matter within soils and moisture content of soils)
• Water table levels
• How extensive are organic soils
• How would an unplanned ground fire affect operations
  • Is excessive smoke production acceptable as determined by smoke screening procedures and local and state laws?
  • Is the ground fire likely to result in escape?
• When necessary, how can fire be excluded from areas of organic soils without causing unwanted ecological damage? (i.e. mowed rather than plowed breaks or very moist environmental conditions.)