How will the L.A. Wildfires affect the San Gabriel Mountain Wilderness?

09/08/2009

California red-legged frogs (Rana draytonii) are one of the species possibly impacted by the wildfires in the San Gabriel mountains near L.A./ Credit G. Fellers, USGS Western Ecological Research Center.

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.

Comments

[Jay Jackson]

This last paragraph is very simple minded and is bound to confuse people. Fires initiate regrowth that greatly increases the postfire capture of CO2, far in excess of what was being absorbed prior to the fire. Currently we lack calculations to determine if what this blog says is correct for chaparral.

[H A Bok]

Good article! Not like the misrepresentations of chaparral fire we usually get in the mainstream media. An additional hazard, especially to amphibians, is the pink fire retardant, Phos-Chek. A study of the Biscuit Fire showed that it can cause mutations and birth defects. Plus the widespread use of bulldozers to cut fire lines can trigger type conversion and erosion. In my neighborhood, we were overrun by invasive spurge and star thistle the year after we had fire lines cut in our local parkland; it was brought from out of our area by the dozer itself.

[Wendee Holtcamp]

Jay - thank you for your feedback. It's always difficlt to capture the details of complex scientific arguments in such a small space, and that paragraph was an aside to the main gist of the story which was on the LA Station fire and the San Gabriel wilderness. I thought it was an interesting aside to mention that deforestation, including fires (often set to cut down Amazon rainforest to make way for ag) are are very large contributor to greenhouse gas emissions. I did not intend to imply that the chaparral fire itself had a big impact on that overall, but rather, I just used the topic as a place to make mention of that interesting statistic. Yes I do understand that fires ultimately allow for regrowth that would then capture more CO2. However, that does not change the reality that deforestation removes more CO2 than transportation and industry, which was the point I was making. Thank you for your feedback and keep reading, maybe I will have a chance to address the topic in greater detail in a future blog post!

[Andrew Mauro]

Excellent article! It's important to recognize the differences between chaparral and "forest" fire ecology. It's hard not to feel depressed when viewing the bleak aftermath of such a large-scale chaparral fire, so it was encouraging to have you point out the natural recovery which can be expected when chaparral fires occur at historical intervals.

[Richard Halsey]

Wendee,

It is so refreshing to see such a well researched article on the fires in Southern California. Thank you for doing the necessary foot work to track down the truth.

With great respect,

Rick

[Halli Mason]

A very well researched and informative article. Dr. Keeley and Mr. Halsey have contributed greatly to understanding the difference between a forest fire and fire in the chaparral, a much misunderstood plant community.
The aftermath of this massive fire will be horrendous as non native plant species will undoubtedly invade the area. Living near the Santa Monica Mountains I have witnessed the invasion of teccalote, horehound, and mustard after fires. The natives will come back, yes. And if the winter rains are gentle, we will even have a beautiful display of annual and perennial native wildflowers. But the invasive species often gain the upper hand if left unchecked. The California Native Plant Society has a strong program to wage war on invasive plant species on public lands. Many volunteers will be needed to help after this huge fire in the San Gabriel Mountains.

[Matthew Sarver]

Wendee - pardon my ignorance regarding the circumstances of this fire, but are folks suggesting that accumulated fuel loads in surrounding forests contributed to the high intensity of this fire within the chaparral systems? Or simply climatic conditions that favored a particularly hot burn?

[Wendee Holtcamp]

Thanks everyone for your kind words about the story - glad you all enjoyed it! I learned something myself in researching it. :) And I lived in Pasadena not too long ago... :)

[Wendee Holtcamp]

Matt - no I do not think that accumulated fuel loads added to the intensity of the fire, as I understand it, nor fuel loads in close-by forests. I am not sure why the reason for the intensity other than it was a severe drought... Maybe someone who knows the system can answer more accurately.

[Susanna]

This is a very informative article. I think the fire was particularly intense because of the extreme heat and low humidy over a long period, added to a drought. Natural fires burn less intensely because they occur during thunderstorms when the weather is humid.

[Drew]

Great article!

H A Bok - Can you please share your source that you refer to in your comment about the toxicity of fire retardants on amphibians. Thanks!

[Wendee Holtcamp]

Matt - I asked Rick Halsey of the California Chaparral Institute your question and this was what he said, "Well, the simple answer is that this fire was not 'particularly' intense. The way the fire burned had nothing to do with unnatural fuel loads. The kind of fire that burned most of the area was a chaparral crown fire. They are 'always' intense. Chaparral fires are always hot and leave a moonscape. That is the nature of the beast. He is probably just picking up on all the generalized comments about the forest paradigm he keeps hearing from people."