Wildfire: Periodic, Beneficial and Inevitable

Are you old enough to remember the U.S. Forest Service-sponsored Smokey-The-Bear ads on television during the 1950’s? For those who are not I must explain. As the story goes the real Smokey The Bear was a bear cub that was severely burned during a wildfire in western forests of North America. Smokey was rescued, cared for and lived a long, natural life after the terrible incident. An offshoot of this was the Forest Service’s television ad that aired year after year and is still alive today….at least on the internet. It features a cartoon character named Smokey wearing a Forest Ranger hat. In a deep voice Smokey simply pointed at the audience and said “Only you can prevent forest fires”. That was it.

The belief at that time was that people caused wildfires through carelessness with campfires, smoking and matches. It followed that in order to prevent them, it was necessary to have a successful campaign to educate the public to be careful with fire when in natural areas.

The Yellowstone Park conflagration of 1988 did more to shape fire management policies than anything else over the last several decades. Most believed it was detrimental. Some saw it as an environmental catastrophe. Regardless of one’s opinion of the benefit or detriment of this fire, it finally taught the federal government’s land managers the futility of preventing naturally occurring fire. Ok, so people often do accidentally or maliciously provide the ignition for forest fires. But Smokey the Forest Service was wrong when they had Smokey tell us that “Only you can prevent forest fires”. If people do not provide ignition it is going to eventually occur anyway.

Why is wildfire a natural, periodic and inevitable event on Earth? Basically there are two reasons. Earth is an oxygen-rich and fuel-rich planet. We all know that there is plenty of oxygen and we know that oxygen is required for fire. But why is Earth fuel-rich? The living star we named Sun is a giant battery that provides the energy that drives natural systems on planet Earth. Photosynthesis, the single most important biochemical process on planet Earth, manufactures inestimable quantities of plant material in natural systems globally during the non-winter growing-seasons. All this living material eventually dies. In those latitudes where solar radiation is intense and the growing season is long, this dead plant material accumulates on the floors of these upland systems faster than it decays. Eventually and inevitably there is ignition. Yes, it is true that the ignition is usually caused by man but historically, even before man arrived on the scene, lightning will eventually provided the ignition. Wildlife in those upland systems, especially in the long growing seasons of the southern latitudes, is natural, periodic and inevitable. Living, herbaceous material eventually dies. And in upland habitats in southern latitudes, herbaceous material is being produced faster than its dead material can decay to become reincorporated into the soil. So the dead material accumulates and eventually there is ignition. In the natural event of fire basic plant nutrients that are locked up in the living plant and are essential for the continuation of vigorous plant growth are suddenly released and deposited on the ecosystem floor where they percolate through the soil horizon and are again taken up by the new plant. This is why following a fire in a field the new grass growth is rich and vibrantly green.

LIGHTNING AND SAWGRASS The combining of lightning and sawgrass has assured that fire has been a major factor in shaping the Everglades ecosystem for as far back as natural historians have documented to date. Lightning, usually beginning at the onset of the rainy season, has always been a ignition source for naturally occurring fires in the Everglades and it touches ground in Florida more frequently than any other place in North America. Overwhelmingly, the leading source of burnable fuel in the Everglades has always been the sawgrass of the marsh. This fire typifies those that have occurred in the Everglades for millennia. This one was ignited by man but the historical ignition source was lightning. Because there was no airboat trails to form firebreaks in the “pre-historic” Everglades, once there was ignition and excluding torrential rain to extinguish them, these fires probably burned for weeks (maybe months), covering perhaps tens of thousands of acres of the vast stands of sawgrass called “sawgrass strands”, until all available sawgrass fuel was consumed. Fires are too often reported as having ” consumed” or “destroyed” so many acres of land. The truth is that sawgrass is perpetuated by fire. Without fire, other, non-fire-tolerant and often exotic plants will succeed the sawgrass. Fire is a natural process that sets back plant succession. Again historically, within several years of such a fire, a random lightning strike would occur again and the process would repeat itself. This is a modern illustration of a natural, periodic and inevitable event that has repeatedly occurred for millennia. Fire perpetuates this sawgrass, still the most abundant habitat in the Everglades. But with pollution from the sugar industry, the invasive, noxious cattail is supplanting sawgrass. It has been estimated that more than 100,000 acres have been lost to cattail as of early 2006. And it is interesting (in a negative way) that cattail habitat does not respond to fire the same that sawgrass does. It has been my experience that stands of cattail will not burn during years of normal rainfall. Of course it would during severe drought. But I have attempted to control-burn in cattails and noted that even following widespread and persistent ignition efforts (from a helicopter) the fire extinguishes. This is either because of an oxygen deficit at the base of the thick cattail stands or the lack of continuity of dead stems. The reason that cattail stands replace the native sawgrass strands is because for decades now the sugar industry has been selfishly and illegally dumping its effluent into the native Everglades…………and Big Sugar’s Florida government crones knowingly and deliberately continue to allow them to do it. For more on this please go the section on Corrupt Corporations. Picture below illustrates how a fire eventually runs out of sawgrass fuel at the edge of a vast strand. . During the rainy season wildfires are numerous, widespread, natural and inevitable. Today, it is not unusual for a single Everglades fire during a drought year, to burn for months. Geologists have unearthed evidence that some Everglades fire burned for more than a year. This is not abnormal or detrimental, as the news media would interpret to you. In fact these fires are natural and beneficial. I am always irked when I see the media describe a wildland following a fire. They say that so many acres were destroyed. In fact, fire unlocks and releases the natural nutrients necessary for plant growth that were locked in the dead plant material. Many Everglades wildflowers bloom immediately and only following fire. The plant associations that evolved in the Everglades are either those that are relatively tolerant of fire or those that have escaped it by being located in habitats that it is unlikely to occur in or reach. The fire cannot reach some habitats because there is not enough fuel continuity on the floor or there is too much moisture in the air. Fire will extinguish and cannot be maintained in high relative humidity. The canopy of a hardwood forest is dense enough to suppress air movement. This keeps the moisture content high enough to suppress fire. I explain. Most of us are aware that the behavior of a fire is greatly affected by air temperature and wind speed. But few are aware of a third factor, relative humidity, that has greater affect on the behavior of a fire than either of the other two. Relative humidity is the amount of moisture in the air at a given temperature, compared to how much moisture the air can hold at that temperature. The “liveliness” of a fire is indirectly related to the RH. As RH increases the fire becomes more sluggish. In fact, if the RH becomes very high it is impossible to keep a fire burning. In very low RH, if there is ignition, it is nearly impossible to control a fire. This is a primary reason for the great difficulty that Western fire crews have in extinguishing the conflagrations that periodically occur out West. Relative humidities in this region are typically far lower than in regions that are near an ocean, where the air moisture is so much higher. Saw palmetto, in the slash pine – saw palmetto flatwoods, is the second leading source of fire and the most important fuel in those elevated ridges that remain, surrounding the Everglades marsh: The fire-tolerant saw palmetto regenerates several months after fire: On the day following a fire in the sawgrass or palmetto, green stems can be found sprouting from all of the plants. And within a few months following a sawgrass burn, only a trained eye can tell there had been a recent fire. Fire managers should work more to assure the media always gets the real story on the effects of a fire. Fire is a natural process that has been recurring on our oxygen-rich planet for millennia. The labeling of fire as being “good” or “bad” is invented by man. Fire is inevitable regardless of what any man thinks of it. Although most of the hardwood trees cannot survive the temperatures of fire, they are located in hammocks and tree islands, where fire does not occur. If fire had reached these areas there would not be hardwood hammocks and tree islands, because the plant species that evolved here have low-survivability in fire. But why does fire not reach these areas except during very severe drought years? The canopy density of these mini-forests, blocks the sufficient sunlight that is needed to develop a lush plant community. So ground cover is sparse. And if the ground cover is sparse there is not sufficient fuel continuity to carry a fire. The second factor that excludes fire from hardwood hammocks and heavily canopied tree island is that the canopy dramatically decreases the evaporational loss of water. Consequently and only under the exception of the most severe drought conditions, the moisture in the understory fuel prohibits it from burning. The RH in these areas is extremely high. Except under drought conditions, fire is beneficial to the living community. Among other things, a major benefit of fire is that it unlocks nutrients from the decaying plant material and deposits it on the marsh for recycling through the living plants. WILDLIFE IN FIRE Studies and field observations have shown that Everglades wildlife have adapted to the event of fire. When you think about, they were obligated to because of the continual inevitability of periodic fire. Although fire often travels rapidly through the sawgrass, the large terrestrial mammals normally have enough mobility to allow them to move out of the way of the advancing fire. The amphibians and other aquatic-dependent animals are much more common to the wet prairies and slough habitats. Although these habitats are immediately adjacent to the sawgrass habitat, it is extremely rare for fire to reach them. And since fire is much more likely to occur within the rainy season, there is a high likelihood of the refuge of water being under the sawgrass. Alligators and turtles are almost always next to a deep source of water. It is true that natural-ignition fires occurred most often during the lightning season, the same season that most ground or low-nesting birds are reproducing. And so it would seem that there would be high mortality. In reality, nestling mortality is probably low in Everglades fires. Few of the low-nesting passerines will nest in the Everglades and those that do, normally don’t choose sawgrass as nesting cover. Just twice I have seen a fledgling passerine bird, a species of sparrow, which I have been unable to identify, rise out of the sawgrass ahead of an advancing fire on what seemed to be its maiden flight. Nests of some of the marsh birds can be found on or near the marsh surface in the summer and late summer, during the lightning season. But these birds do not usually nest in sawgrass either. More frequently they will nest in thick rush, cattail, along the edges of tree islands or under the trees; fire usually will not reach these areas. Rush and cattail are quite green and succulent. And in an Everglades fire that occurs in normally dry conditions, cattail does not burn well and the rush flats do not burn at all. Wading birds nest from December through June in the glades. But their nests are always elevated far above the marsh surface in trees or brush, directly over or near water. Fire is natural and beneficial. And wildlife has adapted to fire, just as the fire-tolerant sawgrass has evolved within it and fire-intolerant plants have become established where fire does not normally occur. But fire is a complex event in which many factors come into play and some wildlife mortality is natural and unavoidable. Ignition in heavy, dry fuel, combined with relatively high winds, results in fire of exceptionally intense heat that rapidly evaporates residual fuel moisture and spreads into areas that it normally would not reach, such as hammocks. Immediately following such a fire I once found a dead armadillo that was unable to escape a fire, which had burned through a hammock. In the grasses of a wet prairie I’ve occasionally bound a box turtle that was injured or perished in fire. The box turtles are very slow and will resort to closing themselves within their plastron-hinged shell when overtaken with fire. But if the fuel is light, the temperatures are usually tolerable and the turtle usually survives the quickly passing fire. The nocturnal green frogs seek daytime refuge in the fronds of the cabbage palms and palmettos. Elevated above the ground surface, a frog is somewhat safer here. Although many of the snakes are arboreal, here the frog is less likely to fall prey to predators. Also, as a shelter, the enveloped configuration of the frond minimized evaporation of body moisture that is vital to the wet-skinned amphibian. But in fire, they are very vulnerable. If it reaches the crowns of cabbage palms, frogs can be seen leaping into space in an attempt to escape the intense heat. The native green anole and exotic brown anole are in a similar plight when fire goes through the palms or palmettos. Although the winged species such as the katydids, winged grasshoppers and butterflies are able to leave an area rapidly, it seems that most of the terrestrial invertebrates, such as wingless insects and spiders, perish in the fire. But their species quickly repopulate the burn area. Using a variation of their web-building technique, spiders are specially adapted for re-inhabiting or migrating to new areas. Did you ever wonder how a spider is able to span its web across a wide path or trail? I’ve even seen several webs that have spanned narrow dirt roads. It seems ludicrous that the creature attaches one end of its silk, crawls down the tree, across the path and up the other tree – and it doesn’t. While remaining grasped to its substrate, the spider begins to release a strand of silk from its spinnerets at the tip of its abdomen. Upon detecting that the released strand of sticky silk has become attached to a piece of downwind vegetation, the spider pulls it tight and has the beginnings of the web. And deliberate or not, spiderlings disperse to new areas in a techniques called ballooning. They raise their abdomen and continually release silk from their spinnerets until a breeze picks them up and carries them to a new locations. On cool mornings following a hot day in which sawgrass fires burned in the Everglades, I’ve found the heavily dewed webs of long-jawed orb weaver spiders on charred sawgrass stems, well within the area that entirely burned the day before. They do it by ballooning. Long-jawed orb weavers are the most common resident spiders in Everglades sawgrass; they seem to occur here in the countless millions. Some species take advantage of the conditions that a fire creates. It rapidly changes the face of the habitat, removing large amounts of dead material and visually opening up the habitat. When fire occurs, a hawk usually moves in. And in the Everglades it’s usually the resident red-shouldered. Apparently undisturbed by the smoke and heat, it chooses an elevated, visually strategic location, immediately adjacent to the burn, waits and watches. Eventually it will glide down from its perch, pick up a snake, frog or rodent and carry it off. Sometimes the hawk is initially seen flying through the smoke and across the burned area with something in its talons. Wading birds are often seen foraging over the wet marsh where fire consumed the available above-water vegetation just days before. Once I observed a water moccasin moving along a dry area of the extreme northern Everglades marsh that had burned days before. Initially, upon seeing me at close range, the snake went into a brief defensive posture, but when I left the immediate area it appeared to resume its business. I assumed it was hunting, as it moved very slowly, continually flicking its tongues. A snake’s tongue, coupled with a special organ, enhances the snake’s ability to sense odors. The tongue picks up odors from air and surrounding objects and sweeps them back to a receptor called the Jacobson’s organ, located within the roof its mouth. At a distance of probably only 20 feet I was beginning to lose sight of it on the charred landscape. Finally, the snake was not visible. There was no doubt in my mind that there had not been enough time for it to leave the area. The charred area was too open for anything to hide on. Peppering the surface of the dry marsh were many small holes that lead to shallow subsurface cavities. The subsurface cavities were a result of the fire consuming the desiccated organic muck. Water moccasins will eat carrion, and apparently this one was hunting the area for animals that were dead or dying as result of the fire. Although some wildlife mortality does occur in a fire, it is eventually compensated for. The energy of all wildlife species is directed toward occupying every available piece of habitat that meets its minimum requirements for survival. Over the long run, habitat will hold no more or no less of each species than it can support. Fluctuation in the numbers of individuals is constant. But the effort to survive is relentless and each species has its periodic reproductive cycle during which mortality is compensated for.

PRESCRIBED FIRE – “Ya don’t burn on a west wind.” In preaboriginal days, fires undoubtedly occurred as result of random lightning strikes in sawgrass strands, and depending on the size and shape of the strand and the wind direction, the fire might burn for many days, into weeks and even months. In some cases fires were often started in small stands, segregated by sloughs or bordering tree islands and unable to continue over a large area. And many of the smaller, segregated strands may have avoided ignition for years. With the advent of Indians and then white man, fires became more frequent. It was used to “cleanse the land” to get rid of ticks and chiggers and to clear areas for grazing, a practice which continues today. And increasingly, fires probably had greater impact, because along with the Whitman came large-scale draining of the swamp and lower water tables. Today, prescribed fires, under controlled conditions, are set by those responsible for managing Everglades habitat. Wildlife management, probably more often than not, consists of the management of wildlife habitat and prescribed fire is one of the tools to that end, which also offers wildlife resource people the opportunity to observe the effects of fire on the habitat. Depending upon jurisdictional lines and management agreements, prescribed fire may be done by Florida’s Division of Forestry, the Florida Game and Fresh Water Fish Commission or Everglades National Park. In the areas of the Everglades that I worked in, north of Tamiami Trail, FGFWFC and DOF worked jointly in prescribed burns. With solar energy, photosynthesis assures that the cycle of plant growth, death and the accumulation of dead material are continuous. Following a sawgrass burn, the regeneration of the strand and resulting accumulation of dead material, assure that conditions are normally set for it to burn again in two years. If a sawgrass strand inadvertently escapes fire, depending upon the depth of muck, it will grow to a dense, ten feet in height. There are over several hundred thousand acres of sawgrass in northern central sections of the Everglades. Historically, these sections had only the natural firebreaks of hammocks, sloughs and wet prairies. And it took just one lightning strike to set the stage for burns that would last for weeks, consuming tens of thousands of acres of dead sawgrass. Even today, with the addition of many airboats trails and camps, there are huge blocks of continuous sawgrass. In the CA3AN compartment, east of the Miami canal, where the largest wading bird rookery in the entire Everglades exists, there are nearly 112,0000 acres of sawgrass. Due to the frequency of lightning strikes alone, this area will inevitably and entirely burn once every 4 or 5 years. On the south, it is bordered by Alligator Alley, the new I-75, and on the east by Us 27. Burning it under controlled conditions requires fairly intense fire management. The practice of controlled burning is an ever-changing applied science, requiring skills in burning and safety techniques and an understanding of an array of weather factors. It has recently evolved from many of the on-ground techniques to one of aerial ignition in which small, chemically combusting plastic balls are continually expelled from a helicopter, flying along pre-set fire lines. This technique enables fire managers to prescribe-burn thousands of acres within a few hours.

JUSTIFYING CONTROLLED BURNING: Whether fire has an overall beneficial or detrimental effect on the habitat of the Everglades has remained an ongoing topic of debate for decades. And although controlled burning is a widely accepted habitat management tool, even the best professional managers of Everglades habitat are divided on this question. Dan beard, in his 1938 report, wrote of the detrimental effects of fires in Everglades National Park. He was correct in his belief that fire burned away the precious and thinly available organic material on the surface of the Miami oolite and that it set back plant succession in hammocks and pine flatwoods, guaranteeing that increasingly these areas would not be able to reach their climax stages. Regardless of one’s beliefs, fires in the Everglades have always been and remain, yearly, numerous, widespread, natural and inevitable. We will see here why fire is also beneficial in many ways. One of the tasks assigned to me a s a wildlife biologist in the Everglades was to plan and coordinate controlled burning of the 750,000 acres north of Tamiami Trail. It made little difference whether I felt burning was beneficial or detrimental; I was given the task of completing it. Everyday I worked with a few people in the field who were outspoken against controlled burning. I worked for supervisors who gave me the task of completing controlled burns. On the question of benefits verses detriments of controlled burning, I remained undecided for my first five years in the Everglades. When I finally began to recognize the inevitability of fire in upland habitats in southern latitudes I then began to ponder if this fire was “good” or “bad”. It does not take much thought to realize that this is like so many other things in nature. Consider predation for example – you may not like it and you may find it revolting, but it is natural and is going to continue, regardless of how it affects you emotionally. So, this fire is only “good” if we want to perpetuate the nature that has evolved here in this fire regime that has been occurring for thousands of years. And of course we do want to perpetuate these species. As a habitat manager, I know, inarguably, fire is the only tool that will reach that end. So the case it closed.

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