But with the increasing frequency and size of fires — 7 of the state’s 10 largest wildfires have occurred in the last six years, and most were caused by people — scientists are intensifying study of the environmental aftermath of the changing burn pattern.  “Fire dynamics have changed a lot, and urbanization has fragmented the landscape,” said Robert N. Fisher, a biologist with the United States Geological Survey, which has coordinated a team to take a closer look at this fire and other recent ones. “We have to figure out a way to give animals a way to persist in a way they did before in a landscape that is burning too fast and too much.”  This week, Mr. Fisher coordinated an unusual evacuation of sorts. A multiagency team of state and federal forest and wildlife representatives removed a colony of mountain yellow-legged tadpoles, endangered in Southern California, from a tributary of the San Gabriel River before rock and debris unleashed by fall and winter rains imperil their creekside habitat.  The tadpoles were taken to the Fresno Chaffee Zoo, where they will be raised, with the young spawned there eventually returned to the wild.  But such maneuvers represent the extreme. Much of the scientists’ work is intended to provide a better understanding of the ecological aftermath of fires, particularly those in areas where development meets wilderness and threatened and endangered species are present.  Scott L. Stephens, a researcher at the University of California, Berkeley, and president of the Association for Fire Ecology, said the Station fire work coincided with a burst of fire science research in recent years designed to answer questions not only about what happens during and after fires but also about the effect climate change and drought may be having on forests and scrubland in high-burn areas.  Underlying much of the interest, Dr. Stephens said, are questions like these: “Are there things we can do to mitigate fire? Are there things managers can do to reduce their impact?”  The Station fire, which was named for its start on Aug. 26 near a ranger station, has destroyed several dozen homes and caused the deaths of two Los Angeles County firefighters. It ranks as the largest fire in the modern history of Los Angeles County. It has burned more than 160,000 acres, or 250 square miles, an area nearly the size of Chicago, and has cut off access to one of Los Angeles’s most popular wilderness getaways, about 20 miles north of downtown.  But the fire may be best remembered for the towering, thundercloud-like plume that loomed for days over the city.  Just what happened to all that ash and how thousands of gallons of fire retardant sprayed on the forest is affecting its creatures is now the focus of much investigation.  Much of the work requires painstaking field research in the deepest reaches of craggy forest.  On a recent afternoon, in the moonscape of the “burn scar,” Mr. Backlin and Ms. Gallegos bounced in a truck along trails and hopped out at the edge of a creek for an afternoon of “fishing.”  With a Forest Service fire truck parked nearby and water-dropping helicopters dashing overhead to hit the last smoldering hot spots, the two cast a literal wide net in an effort to collect small, finger-length speckled daces.  “We’re on fire now,” Mr. Backlin exulted, after several previous efforts turned up nothing but trout and water bugs.  “When the winter rains come, we won’t have any idea what these fish were like if they are washed away,” he said, tossing a few more into a collection bucket.  Later, the two biologists sat in the dirt and measured the specimens, euthanized them and placed them in jars to take back to the laboratory for autopsies.  DNA samples were taken, their internal organs analyzed and other tests performed to assess their overall health and the presence of toxins.  With Forest Service officials already warning that heavy rains could produce severe mudslides because so much vegetation holding the soil in place has burned away, scientists worry about the consequences, particularly to aquatic creatures.  Cascading rock and debris can turn streams into roiling, concrete-like concoctions, burying or shredding all manner of aquatic life, Mr. Fisher said.  Another group of scientists from the Jet Propulsion Laboratory, Arizona State University and the California Institute of Technology plan to take detailed, high-resolution aerial photographs of the burn in the coming days as part of research on erosion and the movement of sediment in the mountains.  “Fire changes a lot of dynamics and releases a lot of sediment,” said Tom Farr, a geologist with the Jet Propulsion Laboratory, whose offices in La Cañada Flintridge abut the forest.  But even without the rain, the fires created a threat.  Already, scientists have found that ash particles in the streams can shred the fish’s gills and drive up the water’s alkalinity, possibly affecting reproduction and setting the stage for die-offs.  A research ecologist, Edward E. Little, said soil and water samples reddened by retardant were being analyzed to determine toxicity to fish and amphibians, among the creatures most susceptible to environmental changes.  Similar work has been done after fires in Colorado and Idaho, Dr. Little said, but “the interesting thing about the Station fire is it is such a different kind of fire than we have visited, in terms of devastation of vegetation in the area.”  Mr. Hoefen, who also helped analyze ash from the World Trade Center collapse, said ash samples had shown elevated levels of minerals that could be the result of what the burned plants had absorbed from the soil or air pollution. They mirror findings from devastating fires in San Diego in 2007, he said, though additional research is needed to pinpoint how harmful the ash could be to human health and the environment.  With rains expected to wash much of the ash into the watershed, Mr. Hoefen said, the quality of rivers, streams and reservoirs could be affected.  “Hopefully, our science will start to show people that it is not just fire, but there could be problems for the frogs, fish and the runoff,” Mr. Hoefen said. “Wind and rain blowing the ash into streams and ponds could have an effect after the fire.”  An article on Saturday about scientists’ work investigating the huge Station wildfire near Los Angeles misstated the given name of a geologist, who said that “fire changes a lot of dynamics and releases a lot of sediment.” He is Tom Farr, not Todd.  A version of this article appears in print on October 3, 2009, on Page A11 of the New York edition with the headline: After a Devastating Fire, an Intense Study of Its Effects. Order Reprints| Today's Paper|Subscribe
Now that the Station Fire that threatened Los Angeles is just about out, scientists are beginning to research the damaging effects of the fire on fragile wildlife.