As the massive wildfire blazes across the southern foothills of the San Gabriel Mountains that separate northern Los Angeles from the Mojave Desert, the animals living in those mountains must escape, burrow, or die. The U.S. Forest Service determined last week that someone set the fire intentionally, rendering the deaths of two firefighters battling the blaze homicides. But what becomes of the ecosystems burned in the fire’s wake, and the wildlife killed or displaced?
When wildfire blazed near Santa Barbara earlier this summer, I blogged about an adorable deer fawn and bobcat cub that became fast friends, and the wild animals and pets that local shelters take in. This time, I focus on the ecosystem damage that results, and potential for eventual regeneration. The “Station fire” near L.A. burned hot enough to melt automobiles, but the results may be ‘not-so-hot’ for the chaparral ecosystems left scorched in its wake.
“Despite being so close to LA, the San Gabriel mountains support some of the greatest biodiversity in the USA,” says Raphael Mazor, a biologist in Southern California currently studying fire impacts on water quality. Four wilderness areas exist in the region, with the San Gabriel Wilderness in the Angeles National Forest most directly affected by this blaze. “[There are] tons of micro-endemic plants up there. As for animals: California red-legged frog, Santa Ana sucker, arroyo chub, bighorn sheep, two-lined garter snake, San Gabriel Mountains slender salamander, and I'm sure several rodents and bat species.”
Mazor says intense, hot fires lead to more mudslides and sedimentation in streams, and are followed by aggressive invasions by invasive plants like mustard (Brassica). Burns can allow invasive plants to get further into wilderness areas as they tend to disperse along roads or open areas.
After the massive 1988 Yellowstone fires brought wildfire smack dab and center in the public's awareness, much media coverage since that time has focused on two things - the benefits of wildfire to fire-adapted ecosystems, and how after decades of fire suppression in some forests, the “fuel” of evergreen needles, dead trees and leaf litter has built up, making these wildfires burn hotter and more intensely. In the long run, though, burns reinvigorate fire-adapted ecosystems, regenerating growth of many tree and plant species, which in turn provides fresh young sprouts for deer and other wildlife. Unfortunately, we have so modified many landscapes, things don’t go the way they historically would have.
The L.A. area fires have burned mostly chaparral, a uniquely Californian semi-arid shrub-dominated ecosystem that covers foothills throughout much of the state. And the chaparral is a ‘whole different animal’ than a fire-suppressed forest. Chaparral does not need fire to exist or remain healthy, nor has excess litter built up due to fire suppression in this particular ecosystem. In fact, excessive fire is now a major threat to the health of the chaparral ecosystem, but nevertheless, the plants and animals there have evolutionary adaptations that help them persist in the long term. “The adaptations that the plants have are like insurance policies,” says Richard Halsey, Director of the California Chaparral Institute, “They don’t want to use the policy, but it is there in case a fire comes…which it will. Old-growth chaparral is one of the most beautiful ecosystems in the world. Unfortunately, so much of it has burned there isn’t much left.” In fact it's a common misconception that the frequent fires occurring in the region help clear out the brush. Even the Angeles National Forest forest supervisor Jody Noiron said on a Los Angeles NBC affiliate last Sunday that the chaparral needed to burn every 10 to 15 years, which is simply wrong. Intense fires like this would historically burn once every 50 to 100 years.
“Although these fires were of high intensity,” says USGS fire ecologist Jon Keeley, “they are not outside the normal range. Our studies show these ecosystems will recover fine.” Wildfires help nutrient cycling and decomposition in dry ecosystems like the San Gabriel Mountains and other California chaparral, including that near the Santa Barbara fires earlier this summer, but one immediate disadvantage is that fires release carbon dioxide into the atmosphere, which contributes to global warming. How the fires will affect individual species that are already rare or endangered is a question only time, and further research, will answer.
Most people don’t realize that deforestation, including fire, is actually the largest overall contributor to greenhouse gas emissions, due to the subsequent loss of carbon storage in trees and shrubs that then gets released into the atmosphere– whereas transportation and industry contribute 14% each. As a caveat, that does not mean that lesser contributors to the problem are not equally responsible for helping to clean up the mess.
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