NASA scientists have determined via an innovative satellite technique that a certain type of wildfire in the Amazon rainforest is responsible for destroying several times more forest than that lost through deforestation in regards to recent years. 
 
 Called “understory fires,” they have long remained hidden because of their location far below the forest treetops; however, using a new method, researchers have developed the first regional estimate of understory fire damage across the southern Amazon. 
 
 "Amazon forests are quite vulnerable to fire, given the frequency of ignitions for deforestation and land management at the forest frontier, but we've never known the regional extent or frequency of these understory fires," Doug Morton of NASA's Goddard Space Flight Center and the study's lead author said in a press release. 
 
 The study, published in Philosophical Transactions of the Royal Society B, demonstrates that, in years with the most understory fire activity, such as 2005, 2007 and 2010, the area of forest affected was several times greater than the area affected by deforestation for expansion of agriculture. 
 
 Moreover, the study goes further, pointing to climate conditions - not deforestation - as the most important factor in determining fire risk in the Amazon at a regional scale. 
 
 Fires in the Amazon's savanna areas can burn quickly, spreading up to 330 feet per minute, according to the researchers, with grasses and shrubs in these ecosystems typically surviving low-intensity surface fires. 
 
 In contrast, understory fires appear "unremarkable when you see them burning," given that the flames reach on average only a few feet high. Capable of lasting for several weeks, they spread only a few feet per minute. 
 
 Despite this seemingly low-key presence, however, understory fires can damage large areas because Amazon trees are not adapted to fire and the long, slow burn can claim anywhere from 10 to 50 percent of the burn area's trees. Furthermore, the recovery that follows is a long, slow process. 
 
 In all, the study shows that between 1999 and 2010, understory forest fires burned more than 33,000 square miles (85,500 square kilometers), or 2.8 percent of the entire forest. 
 
 Meanwhile, results showed no correlation between understory fires and deforestation; in fact, as the pressure for clearing led to the highest deforestation rates ever seen from 2003 to 2004, adjacent forests had some of the lowest rates of fires. 
 
 "You would think that deforestation activity would significantly increase the risk of fires in the adjacent forested area because deforestation fires are massive, towering infernos," Morton said. "You make a bonfire that is a square kilometer in size, throwing ash and live cinders and preheating the adjacent forest. Why didn't we have more understory fires in 2003 and 2004, when deforestation rates were so high?" 
 
 As an answer, the researchers point to climate as the reason that fire-driven deforestation didn;t burn more surrounding forests in these years as frequent understory fire activity coincided with low nighttime humidity, as measured by the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA's Aqua satellite. 
 
 "You can look within an indigenous reserve where there is no deforestation and see enormous understory fires," Morton said. "The human presence at the deforestation frontier leads to a risk of forest fires when climate conditions are suitable for burning, with or without deforestation activity." 
 
 These human sources could include cooking, camping, cigarettes and cars, among other things. 
 
 Going forward, this new understanding regarding the scope of understory fires could have implications for estimates of carbon emissions from disturbed forests, according to the scientists. 
 
 "We don't yet have a robust estimate of what the net carbon emissions are from understory fires, but widespread damages suggest that they are important source of emissions that we need to consider," Morton said. 
 
 Currently, researchers are looking into the climate mechanisms that, given an ignition source from humans, predispose the southern Amazon to burn. 
 
 Among the leading suspects is soil moisture, report scientists at the University of California, Irvine, who are using new information derived from satellite-based measurements of the region that indicate that the amount of water in the ground may be a leading cause for flammability. 
 
 Heading the search is Yang Chen and his colleagues who, in a recent study, were able to show that water storage estimates from NASA's Gravity Recovery and Climate Experiment, or GRACE, satellites allow monitoring of the evolution of dry conditions during the fire season. 
 
 Published in the Journal of Geophysical Research, the study shows how low water storage in the soil leads to a drier near-ground atmosphere, resulting in drier, more flammable vegetation alongside increases in plant litter and fuel availability. 
 
 "A severe fire season in the Amazon is often preceded by low water storage in the soil, and this water deficit in the soil can be detected by the satellites several months before the fire season," Chen said. ||||| Small fires in the Amazon rain forest are having a huge impact. 
 
 A new satellite imaging technique has allowed scientists to see Amazonian fires burning beneath the jungle canopy, called "understory fires," which were previously difficult to detect. These fires destroy several times more forest than is taken out by deforestation each year, according to a new study, published recently in the journal Philosophical Transactions of the Royal Society B. 
 
 Unlike fires in the Amazon's grassy areas, which can spread rapidly and are known to have towering flames, understory fires burn nearly undetected. But between 1999 and 2010, these forest fires burned more than 33,000 square miles (85,500 square kilometers), an area larger than the state of South Carolina, according to a NASA release. 
 
 "Amazon forests are quite vulnerable to fire, given the frequency of ignitions for deforestation and land management at the forest frontier, but we've never known the regional extent or frequency of these understory fires," Doug Morton, a researcher at NASA's Goddard Space Flight Center in Greenbelt, Md., and the study's lead author, said in the statement. 
 
 Signs of damage appear in the year after the fires occur, and then gradually disappear as the rain forest recovers, the NASA statement said. NASA scientists are using an instrument on the Terra satellite to detect these signs of damage, which include slight alterations in the amount and condition of foliage present. 
 
 These fires kill between 10 and 50 percent of the trees in the areas they burn and are likely an important source of carbon emissions that hasn’t been adequately accounted for in climate models, according to NASA. 
 
 The fires only happen when climatic conditions are right — for example, during times of low humidity, according to the statement. The fires usually occur near inhabited areas, however, and are likely ignited by cigarettes, campfires and other human sources, NASA said. 
 
 Email Douglas Main or follow him on Twitter or Google+. Follow us @livescience, Facebookor Google+. Article originally on LiveScience.com. ||||| A forest at first appears devastated after a fire, devoid of color. Ash and smoky plant remains cover the forest floor. In a few short weeks, however, shrubs and forbs will poke through the ash, taking advantage of the nitrogen that was released during the fire. Turkeys will feed on the remains of dead insects, and small mammals will emerge from their burrows to feed on seeds of oaks and hickories, whose thick bark protected them from the heat of the fire. 
 
 But what of less visible animals? Penn State postdoctoral researcher Chris Howey is investigating how fire changes the landscape for often overlooked animals, like reptiles. 
 
 “When you think about the conservation of an animal, you think about food resources and shelter—the physical habitat,” says Howey. “But when you start thinking about reptiles, they go beyond that; they also need thermal resources.” 
 
 As ectotherms, reptiles depend on their surroundings to maintain their body temperature, basking in the sunshine to warm up or seeking shady areas to cool down. This dependence may make them particularly sensitive to changes in the landscape made by burning. To find out, Howey is studying the effects of controlled burns on timber rattlesnakes (Crotalus horridus), which are a candidate species of concern in Pennsylvania and an important part of the food chain. Understanding how timber rattlers respond to fire will help wildlife managers conserve the species. 
 
 Before a burn 
 
 Forest managers in Pennsylvania started using controlled burns in 2010, primarily to remove unwanted or invasive tree species, control insects and disease, or remove forest understory and debris that may fuel larger fires. But fire also changes the habitat of forest animals in more subtle ways, such as by changing the amount of light shining through the canopy, which affects temperatures on the forest floor. 
 
 Before Howey can determine how burning affects rattlesnakes, he must first understand their thermal biology: what temperatures snakes prefer, what temperatures are available to them in an unburned forest, and how those temperatures differ. 
 
 “Snakes in particular are good organisms for looking at questions about thermal biology, because they’re basically just a big tube,” says Howey. “You don’t have to worry about limbs and fur, which affect heat exchange.” 
 
 To determine what temperatures rattlesnakes prefer, Howey brings them into the lab and puts them in a thermal gradient. 
 
 “This is just a really big box that contains a gradient of temperatures ranging from 14 or 16 degrees Celsius [57 to 60 degrees F] all the way up to 42 degrees Celsius [108 degrees F],” says Howey. “This gives snakes an option of temperatures they can choose from.” After a few hours, he measures their internal body temperature, which is called their preferred body temperature. Howey found that on average, rattlesnakes in the thermal gradient preferred a body temperature of around 78°F—much cooler than the human average of 98.6°F. 
 
 “Snakes in particular are good organisms for looking at questions about thermal biology, because they’re basically just a big tube. You don't have to worry about limbs and fur." 
 
 Howey then determines what temperatures are available to snakes in the wild by placing a simple model of a snake at sunny and shady locations around the forest. The model is made of a copper tube painted to match the color of a rattlesnake. A small thermometer inside the tube records the temperature. The model reaches the same temperature that a snake would at that site, and, because it’s made of metal, it warms up faster than a snake would, allowing Howey to quickly obtain readings. 
 
 Howey then compares the temperatures that snakes prefer in the lab to those available in forests. His work with the snake models shows that snakes basking at various locations on the forest floor would only occasionally reach temperatures as high as 78°F, even during the summer, meaning good basking spots may rarely be available to snakes in the wild. Snakes can survive at lower temperatures, but they likely do not perform as well as they could. 
 
 Consequences of Burning 
 
 Because good basking spots may be uncommon in unburned forests, prescribed burning may actually improve the thermal landscape for rattlesnakes. 
 
 “As we burn the landscape, we’re going to remove a lot of the understory vegetation, and potentially some overstory vegetation, like big trees,” says Howey. “By decreasing this ‘roof,’ we’re going to provide them with more opportunities to bask in the open and to maintain a warmer body temperature. This then could translate to things like digesting a meal a little bit better, growing a little bit faster, reaching sexual maturity sooner, and maybe even having more babies. And this is going to improve the population overall.” 
 
 How does fire affect snakes? Penn State postdoctoral researcher Chris Howey is investigating how timber rattlesnakes respond to prescribed fire. Because burning opens up the canopy and removes understory plants, it allows more sunlight to reach the forest floor and may create more basking opportunities for rattlesnakes. Image Gallery firesnake-1sunlight crop Sun shines through the tree canopy, creating a spotty canvas of light on the forest floor. Timber rattlesnakes bask in sunny areas in order to absorb the heat they need. Fire changes the forest canopy and thus the mosaic of light and temperatures on the forest floor. The rattle of this snake has been marked with Wite-Out® so that Howey and his team can easily identify it in the wild. IMAGE: Chris Howey, Penn State 
 
 firesnake-2handling-crop Howey follows a strict safety protocol when capturing a timber rattlesnake. Once safely contained in the bucket, a snake is brought into the lab and implanted with a radio transmitter. Howey plans to track snakes before, during, and after prescribed fires to determine whether burning changes where they bask and forage. IMAGE: Tracy Langkilde, Penn State 
 
 firesnake-3fire An ignitor with the Bureau of Forestry lays a line of fire during a prescribed burn. He walks along the “fire break,” an area around the edges of the burn that has been cleared of brush, leaves, and debris in order to confine the fire to a designated area. Some fires in Pennsylvania are as small as 10 to 50 acres, while larger burns can span 150 acres. IMAGE: Chris Howey, Penn State 
 
 firesnake-4tree Fires remove understory plants and debris, and also clear out some trees in the overstory, leaving ash and scorched bark in their wake. Seeds from fire-resistant species such as oaks and hickories survive and support small mammals and other wildlife after the burn. IMAGE: Chris Howey, Penn State 
 
 firesnake-5rocks While rocks often provide protection from predators, they may not provide sufficient protection from fire. By radio-tracking snakes during prescribed burns, Howey hopes to determine how they survive. Some snake species hide under large structures or go underground, but Howey does not yet know what timber rattlesnakes do during a burn. “Fire is a natural occurrence within the landscape,” says Howey, “so you would assume they would have evolved alongside of it.” IMAGE: Chris Howey, Penn State 
 
 firesnake-6Hawk crop By opening up the landscape, a burn may provide more basking areas for snakes, but it may also increase their visibility to predators such as hawks and bears. IMAGE: copyright Chris Camacho, Concertina Consulting LLC 
 
 firesnake-7vernalpool Howey and graduate student Michaleia Mead are also investigating how fire affects animals that use vernal pools, temporary ponds that form in springtime and serve as breeding grounds for frogs and salamanders. They wonder if fire-induced changes in water quality and the amount of UV light reaching the pond affect amphibian development. IMAGE: Chris Howey, Penn State 
 
 Burning may help snakes in other ways, too. 
 
 “Following a burn, we start to see a lot of regeneration of seed-bearing plants and oaks. This is going to provide food for things like rodents and they are going to be food for rattlesnakes.” To assess this, Howey and his team are measuring the abundance of acorns and small mammals before and after a burn. 
 
 Although burning may increase numbers of prey, the openness of burned sites may also lead to increased numbers of predators, such as hawks, bears, and raccoons. 
 
 “If we have a site that’s too open, we may start to get more predators,” says Howey. “So we’re trying to find a happy medium where we have good thermal quality but not as many predators.” 
 
 Surviving the burn 
 
 But how do rattlesnakes survive the burn itself? 
 
 “We don’t know,” says Howey. “One of the big objectives of this project is to figure out what rattlesnakes here in Pennsylvania do to survive a prescribed burn. Fire is a natural occurrence within the landscape, and so you would assume they would have evolved alongside of it.” Some snake species flee underground or under structures that are large enough to protect them during a fire. Some rattlesnake species, however, flee into brush piles, which soon become engulfed in flames. 
 
 “That’s obviously not a good escape tactic,” says Howey. “We don’t know yet whether or not our snakes will do these behaviors.” 
 
 "Fire is a natural occurrence within the landscape, and so you would assume they would have evolved alongside of it." 
 
 To find out, he is radio-tracking rattlesnakes before, during, and after prescribed burns. 
 
 “We capture a snake, bring it back to the lab, anesthetize it, and surgically implant a transmitter into the body cavity,” says Howey. “Then we give the animal a couple days to heal—they heal very, very quickly—and then we release it.” 
 
 The transmitters are smaller than one’s thumb and weigh just over 3 grams, or about 2% of a snake’s natural body weight. 
 
 “The animal knows it’s carrying something around,” says Howey, “but it’s very minimal to them.” 
 
 Howey says he can track a snake for up to two years before the battery dies. He brings the snake back to the lab to remove the transmitter before that occurs. 
 
 The tracking will reveal how much time snakes spend at different sites throughout the day, allowing Howey to determine whether fire changes where snakes bask or look for food. In addition to providing location data, the radio transmitter also detects the temperature of the snake and changes in its pulse rate as the snake gets warmer. This will indicate whether snakes are maintaining non-ideal body temperatures at certain sites. 
 
 Depending on how snakes respond during the burn itself, forest managers could alter when they perform prescribed burns. Burns are usually conducted during the spring, after the trees leaf out. 
 
 “In the spring, all their energy resources are in those leaves. In the wintertime, all of their energy resources are in the roots, so if you burn at that time you’re not really having much of an impact,” says Howey. 
 
 But spring is also when rattlesnakes are most active. If they are able to survive the burn, by fleeing underground for example, then burns can be performed during the spring without any negative effects on the snakes. 
 
 “But if burning does have negative consequences directly on snakes, if more of them die in the burn, maybe we need to burn more in the winter, or before the rattlesnakes become active out on the landscape.” 
 
 Why help snakes? 
 
 Rattlesnakes are dangerous, but their reputation may be exaggerated. In Pennsylvania, there has only been one human death in recorded history due to a rattlesnake bite, and that individual had an allergic reaction to the venom. Typically, individuals who receive antivenin within an hour or two of being bitten will be not suffer lasting ill effects. Nonetheless, Howey and his team follow a strict safety protocol around rattlesnakes. 
 
 “They really only rattle when they feel threatened, and then they’re mainly letting you know, ‘Hey, I’m here, please leave me alone.’ ” 
 
 Some may question the wisdom of increasing timber rattlesnake numbers. But Howey doesn’t think that more snakes will mean more encounters with humans. We rarely notice rattlesnakes, he says, partly because they rarely rattle. 
 
 “They really only rattle when they feel threatened, and then they’re mainly letting you know, ‘Hey, I’m here, please leave me alone.’ ” 
 
 Interactions between humans and rattlesnakes usually occur around trails, according to Howey, and, after a burn, humans will probably encounter snakes more often only if we encroach on their habitat. 
 
 Besides, having more rattlesnakes in forests could actually benefit humans. Rattlesnakes help keep rodent populations in check, which are a major vector of the ticks that carry Lyme disease and other pathogens. Controlling rodent populations may also help other important species that compete with them for food, such as deer and wild turkey. 
 
 “I’m not saying we need to be overrun by rattlesnakes,” says Howey, “but having a healthy presence of them within the landscape would be a really good thing.” 
 
 Chris Howey is a postdoctoral researcher in the lab of biologist Tracy Langkilde.
– Someone flying above the Amazon in a plane would see nothing amiss, but scores of small, slow-moving fires beneath the canopy of trees are destroying more land than deforestation, reports LiveScience. New satellite imaging from NASA has revealed these so-called "understory fires." Flames are only a few feet high, and the fires themselves move only a few feet per minute, but they can last several weeks, reports Nature World News. The culprit? Careless humans, apparently. These fires generally occur near populated areas, and they're often set off by campfires or discarded cigarettes—aided and abetted by low humidity. NASA researchers say the discovery of the fires will affect climate models. "We don't yet have a robust estimate of what the net carbon emissions are from understory fires, but widespread damages suggest that they are important source of emissions that we need to consider," says one.