California’s Desert Ecosystems Will Never Recover

California’s Desert Ecosystems Will Never Recover

California’s Desert Ecosystems Will Never Recover

Fire in the Anthropocene has become the environmental equivalent of nuclear war.

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In Greener Than You Think, a 1947 novel by the left-wing sci-fi writer Ward Moore, a mad woman scientist in Los Angeles recruits a down-and-out salesman named Albert Weener, described as having “all the earmarks of a castiron moocher,” to help promote her discovery: a compound called Metamorphizer that enhances the growth of grasses and allows them to thrive on barren and rocky soils. The scientist dreams of permanently ending world hunger through a massive expansion of the range of wheat and other grains; Weener, a scientific ignoramus, thinks only of making a quick buck peddling the stuff door-to-door as a lawn treatment. Desperately needing cash to continue her research, she reluctantly agrees, and Weener heads out to the yellowed lawns of tired bungalow neighborhoods.

To his surprise, the treatment, which alters grass genes, works—only too well. In the yard of the Dinkman family, crabgrass is converted into a nightmare “Devil Grass,” resistant to mowing and weed killers, that begins to spread across the city. “It writhed and twisted in nightmarish unease…inexorably enveloping everything in its path. A crack in the roadway disappeared under it, a shrub was swallowed up, a patch of wall vanished.” It continues to eat pavement and houses and finally consumes the city: a monstrous new nature creeping toward Bethlehem.

Greener Than You Think is both hilarious and slightly unnerving. But its absurd premise is being turned into current events by climate change. Our Devil Grass is Bromus, a genus of invasive and almost ineradicable grasses bearing appropriately unsavory names like ripgut brome, cheatgrass, and false brome. Originating in the Mediterranean and the Middle East, some species have been around California since the Gold Rush, when overgrazing allowed the bromes and European oat grass to aggressively replace native species. But now fire and exurban sprawl have become their Metamorphizers as they conquer virtually every ecosystem in the state.

The Eastern Mojave Desert is a grim example. If you drive from LA to Vegas, 20 minutes from the state line, there’s an exit from Interstate 15 to a two-lane blacktop called Cima Road. It’s the unassuming portal to one of North America’s most magical forests: countless miles of old-growth Joshua trees mantling a field of small Pleistocene volcanoes known as the Cima Dome. The monarchs of this forest are 30 feet high and centuries old. In mid-August an estimated 1.3 million of these astonishing giant yuccas perished in the lightning-ignited Dome Fire. This wasn’t the first time the Eastern Mojave burned. A megafire in 2005 scorched a million acres of desert, but it spared the Dome, the heart of the forest. Over the last generation, an invasion of red brome has created a flammable understory to the Joshuas and transformed the Mojave into a fire ecology. (Invasive cheatgrass and wire grass have played similar roles in the Great Basin and the Pacific Northwest.)

Most desert plants, unlike California oaks and chaparral, are not fire-adapted, so their recovery may be impossible. Debra Hughson, the chief of science at the Mojave National Preserve, described the fire as an extinction event in an interview with the Desert Sun. “The Joshua trees are very flammable. They’ll die, and they won’t come back.”

Our burning deserts are regional expressions of a global trend: the fire-driven transformation and replacement of native land cover from Greenland to Hawaii. Even the Antarctic Peninsula now has an invasive weed problem. In most cases, exotic plants—especially annual grasses and forbs (herblike plants)—are the culprits. In southeastern US forests the devil is cogongrass from East Asia; in Australia, buffel grass from India; and in Hawaii, guinea grass from Africa.

Bromes, superbly adapted to the Anthropocene, rule the West Coast. As Travis Bean, a weed scientist at the University of California, Riverside, warned last year, “We have all of the nasty nonnative Bromus species here in California, and these weeds are key drivers of increasing fire frequency.” Increased fire frequency, in turn, opens spaces for the propagation of these fast-growing and easily dispersed species. Whereas recovering mountain chaparral, for instance, requires 20 years to mature before it can burn, bromes need only one or two winters’ rain to produce enough flammable biomass to sustain a large fire. Once established, the ensuing invasive-grass and fire cycle is almost irreversible.

This is especially true in Mediterranean biomes, despite the fact that their vegetation has evolved with fire and requires episodic burns to reproduce. The current wave of annual extreme fires in the Iberian Peninsula, Greece, Australia, and California is overriding Holocene adaptations and pushing native ecosystems, many of them already degraded, past their survival tipping points.

Although Australia is a close contender, California best illustrates the vicious circle in which extreme heat leads to frequent extreme fires that prevent natural regeneration—and with the help of tree diseases, accelerate the conversion of iconic landscapes into parched grasslands and treeless mountain slopes. And with the loss of native plants goes much of the native fauna, from lizards to songbirds.

Climate change drives landscape conversion in several ways. At the beginning of this century, state water planners and fire authorities were primarily focused on the threat of multiyear droughts caused by intensified La Niña episodes and stubbornly persistent high-pressure domes. Their worst fears were realized in the great drought of the last decade, perhaps the worst in 500 years, which contributed to the death of an estimated 150 million bark-beetle-infested trees that subsequently provided fuel for the firestorms of 2017 and 2018.

Similarly, over the past 20 years, an exponentially spreading fungal pandemic called sudden oak death has killed millions of live oaks and tan oaks from Big Sur to southwestern Oregon. Climate change, which increases heat and drought, facilitates this disease and drives its spread. Since the tan oaks, especially, grow in forests with Douglas firs, redwoods, and ponderosa pines, their dead hulks act as force multipliers in the firestorms raging in coastal mountains and the Sierra foothills.

In addition to ordinary droughts, scientists now talk about a new phenomenon, the hot drought. Even in years with average 20th century rainfall, extreme summer heat—our new normal—is producing massive water deficits through evaporation from reservoirs, streams, and rivers. In the case of Southern California’s lifeline, the lower Colorado River, a staggering 20 percent decrease in the current flow has been predicted within a few decades, independent of whether precipitation declines.

But the most devastating impact of the Death Valley–like temperatures (it was 121 degrees in the San Fernando Valley in early September) is the loss of plant and soil moisture. A wet winter and early spring may mesmerize us with extravagant displays of wildflowers, but they also produce bumper crops of grasses and forbs that are then baked in our furnace summers to become fuel when the devil winds return.

The bromes and other pyromaniacal weeds like black mustard are the chief by-products and facilitators of this new fire regime. Years of research at experimental plots, where scientists burn different types of vegetation and study their fire behavior, has confirmed their Darwinian edge. They burn at twice the temperature of herbaceous ground cover, vaporizing soil nutrients essential to the regeneration of native species. Bromes also thrive on air pollution (a nitrogen fertilizer), can quickly evolve resistance to herbicides, and are more efficient than most plants in utilizing higher levels of carbon dioxide—big evolutionary advantages in the current struggle between ecosystems.

Until recently, it was widely believed that the West Coast’s closed-canopy forests were largely invulnerable to the brome threat because they are too cool and shaded. But now a group of researchers from Oregon State University’s College of Forestry and the US Forest Service that is studying the question warns forest managers that false brome adapts well to the forest gloom, and cheatgrass immediately colonizes forest burn sites. Once a durable feedback loop with fire is established, a forest grass invasion becomes, in the researchers’ words, a “perfect storm.”

And like Moore’s Devil Grass, the invaders defy human will. “Management actions such as thinning and prescribed fire, often designed to alleviate threats related to wildfires, may also exacerbate grass invasion and increase fine fuels, with potential landscape scale consequences that are largely underrecognized,” the group reported. In other words, some of the textbook prescriptions for reducing fire hazards may only reproduce them in a new form—something that is poorly understood by public officials.

This is the Achilles’ heel of the emergency legislation that California Senator Dianne Feinstein, with the support of the state’s governor, Gavin Newsom, is trying to push through Congress. The bill would override federal environmental regulations to accelerate the removal of dead trees and the clearance of chaparral and brush—yet the cleared landscapes would be inviting to bromes, which have the ability to generate huge fuel loads annually. (Also the deadwood would presumably be burned, contrary to carbon reduction mandates.)

Only a sustained annual effort to reduce grass biomass reseeding—something that would require a large army of full-time forest workers and the cooperation of landowners—could, theoretically, postpone the weed apocalypse. It would also require a moratorium on new construction as well as on postfire rebuilding in the most hazardous areas, measures that are hardly palatable in the state capital, Sacramento, even in the era of a Democratic supermajority.

After every fire emergency, Newsom and other liberals call for urgent action to reduce emissions. But in doing so, they deliberately elide the question of what needs to be done on the ground, here and now. Such an agenda would have to directly confront the sprawl along what fire experts label the wildland-urban interface.

A large share of new housing in California over the past 20 years has been built, profitably but insanely, in high-fire-risk areas like the Sierra foothills. By one estimate, a quarter of the state’s population now lives in these interface areas—with scores of new developments and master-planned communities in the pipeline. (In San Diego County alone, supervisors recently approved 10,000 new homes in extreme-fire-hazard locations in the backcountry.) Since 40 percent of the state’s 33 million acres of forest are privately owned (57 percent is federal land, and only 3 percent under state or local control), there are few constraints on future development.

The expansion of the residential frontier into disaster-prone landscapes isn’t just a California trend; think of the building boom on Atlantic and Gulf Coast barrier islands that become submerged in hurricane storm surges. According to geographers Laura Taylor and Patrick Hurley, “Despite the common perception that the United States has become a ‘suburban nation,’ exurbia has emerged as the dominant settlement pattern across the country, characterized by different patterns of development and different lifestyle expectations from cities, towns, and suburbs, with houses in scenic, natural areas on relatively large acreages (often with one house per 10, 20, or 40 acres or more).”

But there are two very different kinds of migrants to the exurbs. Some, like the inhabitants of Paradise, the Sierra foothill city incinerated in 2018, are rent refugees from the state’s housing crisis or ordinary folks, especially retirees, who want to own a tiny piece of California’s beauty. But they are minor players compared with the influx of wealth from the coast. Rural areas that were once ruggedly blue-collar and derided as “Appalachia” (an insult long attached to eastern San Diego County, where I grew up) now boast starter castles, high-end subdivisions, and spa retreats. From Mendocino on the north coast to the San Diego mountains in the south, upper 5 percent migration has been gentrifying the urban hinterlands, especially those areas with high-value amenities like ocean views, wineries, and forest lakes.

An equally prized amenity is their racial homogeneity. “Exurbanization” is often a euphemism for white flight from metropolitan diversity. As California’s suburbs turn Technicolor and become more Democratic, the exurbs (with some exceptions) are hard-core Donald Trump country and are fiercely anti-government—except in fire season. One of their leading voices was Duncan Hunter Jr., now on his way from Congress to prison, who represented the exurban corridor along I-15 from San Diego to Riverside. For years he fought restrictions on backcountry development with the same zeal that he opposed Latino immigrants and unions.

This is a mindset, blind to the consequences, that allies itself with the botanical counterrevolution. Relentless land clearance and home construction fragment habitats, introduce myriad fire ignition sources, and promote weed invasion. Yet the newcomers are unwilling to pay taxes for increased fire protection—and raise hell when foresters attempt prescribed burns. Meanwhile, shorthanded fire crews are under tremendous pressure to defend individual homesites, which has led to increased deaths and injuries.

Exurbanites seem incapable of learning the obvious lessons from recent megafires. In 2003 a firestorm destroyed more than 1,000 homes in the unincorporated towns of Alpine and Crest in the mountains east of San Diego. When I took a film crew there last year, the lost homes had been replaced by even larger ones, and residents assured us that thanks to brush clearance, the fire hazard had been mitigated. But the quest for defensible space, zealously marketed by developers and local officials, is a dangerous mirage. Firestorms that create their own tornadic weather systems and can hurl fiery debris a kilometer ahead of the flame front are not deterred by a 300-foot circumference of brush clearance or a few carefully watered beds of ice plant.

How should we understand the large-scale ecological consequences of the invasive-grass and wildfire cycle? One perhaps surprising analogue is the aftermath of the firebombing of Germany during World War II. In the late 1940s the ruins of Berlin became a laboratory where natural scientists studied plant succession. The expectation was that the original vegetation of the region—oak woodlands and their shrubs—would soon reestablish itself. To the scientists’ horror, this was not the case. Instead escaped exotics, some of them rare garden plants, established themselves as the new dominants.

The botanists continued their studies until the last bomb sites were cleared in the 1980s. The persistence of this dead-zone vegetation and the failure of the plants of the Pomeranian woodlands to reestablish themselves prompted a debate about Nature II. The contention was that the extreme heat from firebombing and the pulverization of brick structures had created a soil type that invited colonization by rugged plants such as tree of heaven (Ailanthus altissima) that had evolved on the moraines of Pleistocene ice sheets. An all-out nuclear war, they warned, might reproduce these conditions on a vast scale.

Fire in the Anthropocene has become the physical equivalent of nuclear war. In the aftermath of Victoria’s Black Saturday fires in early 2009, Australian scientists calculated that their released energy equaled 1,500 Hiroshima-size explosions. Even greater energy has produced the pyrocumulus plumes that for weeks have towered over Northern California and Oregon. Likewise the toxic orange fog that shrouded the Bay Area for weeks might be considered a miniature nuclear winter.

As a result, a new, profoundly sinister nature is rapidly emerging from our fire rubble at the expense of landscapes we once considered sacred. Our imaginations can barely encompass the speed or scale of the catastrophe.

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