What’s Natural?
Guest post by Jim Steele
There are several theories trying to explain the recent uptick in wildfires throughout the western USA. Some scientists blame increased human ignitions. Others suggest accumulating surface fuels due to a century of fire suppression. Others argue landscape changes and invasive grasses have amplified the amount of easily ignited vegetation, while still others blame climate change. What’s the Sage Grouse connection? Like human communities, the Sage Grouse’s habitat is being threatened by fast spreading wildfires, and that increase in bigger wildfires in sagebrush country is due to invading annual grasses, like cheatgrass.
Historically hot dry sagebrush habitat rarely burned (just once every 60-100 years) because slow growing, patchy sagebrush only provides scant surface fuels incapable of supporting large and frequent fires. But the invasion of introduced annual grasses, like cheatgrass, has changed all that. As one wildlife researcher lamented, “The color of Nevada has changed from a sagebrush silver gray to a cheatgrass tawny brown since the 1990s”. Likewise, in the 1800s California’s hills were covered with perennial grasses that stayed green during the summer. Now California’s hills are golden brown as highly flammable annual grasses have taken over.
Cheat grass-dominated sagebrush habitat now burns every 3-5 years, up to 20 times more frequently than historic natural conditions. Extensive research on the effects of cheat grass found habitats with high cheat grass abundance are “twice as likely to burn as those with low abundance, and four times more likely to burn multiple times between 2000-2015.” What makes cheatgrass such a problem?
Invading annual grasses germinate earlier in the season and deprive the later-germinating native grasses of needed moisture. These foreign grasses die after setting seed, leaving highly flammable fuels that can burn much earlier in the year and thus extend the fire season. Eleven of the USA’s 50 biggest fires in last 20 years have been in Great Basin sagebrush habitats, where invasive cheatgrass is spreading. Nevada’s largest fire was the 2018 Martin Fire. Rapidly spreading through the cheat grass, it burned 439,000 acres, a burned area rivaling California’s largest fires in recorded history.
The 2012 Rush Fire was California’s 4th largest fire since 1932, burning 272,000 acres of sagebrush habitat in northeastern California. It then continued to spread burning an additional 43,000 acres in Nevada. The 2018 Carr Fire was California’s 7th largest fire and threatened the town of Redding, California. It started when a towed trailer blew a tire causing its wheel rim to scrape the asphalt. The resulting sparks were enough to ignite roadside grasses. Grassfires then carried the flames into the shrublands and forests, where burning grasses served as kindling to ignite less-flammable trees. Likewise, grasses were critical in spreading northern California’s biggest fires. In southern California, as humans ignite more and more fires, shrublands are being converted to more flammable grasslands.
Wildfire experts classify grasses as 1-hour fine fuels, meaning dead grass becomes highly flammable with just one hour of warm dry conditions. When experts estimate impending fire danger, they calculate the extent of a region’s fine fuels to determine how fast a fire will spread. The amount of small diameter fuels like grasses that can dry out in an hour, as well as twigs and small branches that dry out within 10 to 100 hours of dry weather, determine how fast the winds will spread a fire. It does not matter if it was wet and cool, or hot and dry during previous weeks or years. Just one hour of warm dry fire weather sets the stage for an explosive grass fire. Decades of climate change are totally irrelevant.
Some scientists point out that certain logging practices also spread “invasive grasses”. For that reason, California’s Democrat congressman, Ro Khanna, has been arguing that the U.S. Forest Service policy to clear cut after a wildfire is making California’s forest fires spread faster and burn hotter by increasing the forest floor’s flammable debris. Khanna warns, “Because we don’t have the right science, it is costing us lives, and that is the urgency of getting this right.”
Bad analyses promote bad remedies and blaming climate change has distracted people from real solutions. The “cheatgrass” problem will continue to cause bigger fast-moving fires no matter how the climate changes. But there are several tactics that could provide better remedies. Holistic grazing that targets annual grasses before they set seed is one tactic. Better management of surface fuels via prescribed burns is another, as well as more careful logging practices. And re-seeding habitat with native perennial grasses or sagebrush could help shift the competitive balance away from cheatgrass. In combination with limiting human ignitions, (see part 2), all those tactics may ensure healthy populations of Sage Grouse living alongside safer human communities.
Jim Steele is Director emeritus of San Francisco State’s Sierra Nevada Field Campus and authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism
Great post, Jim Steele, and, as usual, right on the money. As a geologist working and camping out a lot in northern Nevada I can assure you that you do not camp, or even loiter (work?) in a dead end canyon downwind with thunderstorms around in cheatgrass country. The fires in dry cheatgrass run so fast it is hard to imagine. Sage grouse? Tasty critters!
Historically hot dry sagebrush habitat rarely burned (just once every 60-100 years)
Please cite your sources. My research indicates that human beings have occupied the Great Basin for at least 11,000 years (and at least 15,000 years in So. Cal.). Those residents burned their habitats frequently. Anthropogenic fire was practiced every year, though not always on the same patch. The fire return interval for the average acre was less than 10 years. Another way to state this, using statistical survival analysis terms, is that the likelihood of any acre remaining unburned (surviving) was less than 10 years.
Others suggest accumulating surface fuels due to a century of fire suppression.
For at least 11,000 to 15,000 years the principal fire ignition factor was human beings, not lightning. The usage of “fire suppression” implies that for the last 100 years moderns have been suppressing lightning fires in sage brush, chaparral, grasslands, and currently forested areas. That is incorrect. Historically (for millennia) the ignition source across North America has been human beings. What was suppressed is the indigenous cultural practice of land management via anthropogenic fire. The resident indigenous people were decimated by Old World diseases and removal to reservations. That is why anthropogenic fires ceased.
It is a common misconception to assume that nature is a deterministic machine that operates or operated in the absence of humanity. This misconception arises from a neo-Puritan neo-Victorian world view that discounts the scientific historical true fact that human beings have played a dominant role in nature since time immemorial. Ecological analyses that deny historical human influences upon or to the environment are simply wrong. “Solutions” that rely on faulty analyses are unlikely to succeed — on this point we agree.
Mike Dubrasich,
Please site YOUR references Mike. One reference to the 60-100 years sagebrush cycle can be found if you click on the Sage Grouse link in my essay.
Furthermore fire suppression has very much been a factor and it is you whose argument is very much incorrect. Clearly you do not have a fire ecology background. Indeed native Americans were lighting fires but I identifying how much versus lightning is not quantifiable. Europeans began suppressing fires whether started by Native American or by lightning. For decades fire ecologists have been warning fire suppression will result in bigger more intense fires. Many argued we need to manage the forests with prescribed burns in much the same way Native Americans hd done.
Mike Dubrasich:
“The fire return interval for the average acre was less than 10 years. Another way to state this, using statistical survival analysis terms, is that the likelihood of any acre remaining unburned (surviving) was less than 10 years.”
So, you are saying every acre of sagebrush habitat burns at least once every ten years? Have you ever even been to the Great Basin? If you had you would realize how stupid those statements are.