SOS Forests

Apache Burning in Lightning’s Epicenter

The Chiricahua Mountains in SE Arizona are one of the Madrean Sky Islands [here], volcanic massifs that rise above the Southwest desert basins and which include the Pinaleño, Pedragosa, Peloncillo, Baboquivari, Santa Catalina, and Santa Rita Mountains among others. The higher elevations harbor diverse ecological assemblages, such as pine and fir forests that are quite different from the Sonoran desert vegetation that surrounds them.

The Sky Islands are lightning magnets. Summer thunderstorms ride the Mexican Monsoon and punctuate the Sky Islands with the densest frequency of lightning bolts in the U.S. And yet, despite all that loose electricity and resulting fires, the vegetation of the Chiricahua Mountains has been dominated by anthropogenic (human-set) fire for millennia.

That historical fact is explored by Dr. Stephen J. Pyne, World’s Foremost Authority on Fire, in a new essay, Rhymes With Chiricahua [here].

There is little question that lightning is adequate to kindle copious fires and that the extent of burning aligns smartly with the ebb and flow of atmospheric moisture. Connect the sky island dots with the volcanic edge of the Colorado Plateau, and the resulting circle will trace the epicenter for lightning-caused fire in the United States. Like a rocky outlier that catches the first swells of an approaching storm, the bulky, border-hugging Chiricahuas make first contact with the Mexican monsoon, the signature onset of the southwestern fire season. …

But if the obvious beguiles, it is the second-order reasoning that proves treacherous. If you look at such data by itself, you might well conclude that climate alone “drives” the fire regime. Such analysis reduces a complex poker game to a game of solitaire: you can only play the cards nature hands you. The reality, however, is that there is another player at the table, and he is the dealer.

Humanity is the Earth’s keystone species for fire, not only as a source of ignition but as a sculptor of landscape fuels. It is significant that this second source was present from the onset of the Holocene, or what is more aptly being called the Anthropocene. There has been no time since the end of the last glacial when the region lacked an ignition source both more promiscuous and more prescribed than lightning.

Dr. Charles Kay examined the relative fire contributions of humanity and lightning in his seminal report, Are Lightning Fires Unnatural? A Comparison of Aboriginal and Lightning Ignition Rates in the United States [here]. Kay found that humanity during the “Anthropocene” has been winning the contest hands down:

Using the lowest published estimate of native people in the United States and Canada prior to European influences (2 million) and assuming that each individual started only 1 fire per year—potential aboriginal ignition rates were 2.7–350 times greater than current lightning ignition rates. Using more realistic estimates of native populations, as well as the number of fires each person started per year, potential aboriginal ignition rates were 270–35,000 times greater than known lightning ignition rates. Thus, lightning-caused fires may have been largely irrelevant for at least the last 10,000 years. Instead, the dominant ecological force likely has been aboriginal burning.

Even in the lightning-lit Chiricahuas, human manipulation of the environment has dominated and produced vegetative patterns that persist despite annual lightning fire.

But the human element was eliminated in the late 1800’s, and the traditional burning all but ceased. From Rhymes With Chiricahua:

The collapse of the Anasazi and Hohokam civilizations in the 12th and 13th centuries created a major vacuum in the historical geography of human habitation. The Athabascan-speaking Apaches moved from the western grasslands into the grassy semi-desert and then, at least seasonally, into the grassy-understory forests of the Sky Islands and Mogollon Rim. They carried their fire practices with them. The suppression of the Pueblo revolt of 1680 created another rupture. The infiltration of the Spanish mission system consolidated some tribes while evicting and resettling others. In 1762, for example, Spanish officials effectively emptied the San Pedro valley by relocating Northern Pimas to the Santa Cruz River valley.

That created a borderlands area between old-resident Pimans and new-arrival Apaches. The region underwent regime change from quasi-permanent habitation to intermittent occupation, as the landscape became a war zone, partly occupied, often fought over, burned for battles as well as for hunts and foraging. Then the historic dynamic reached far beyond the grasp of mission and presidio by replacing the extinct megafauna with horses, cattle, sheep, goats, burros, and swine, all of which competed not only with wildlife but with fire. In principle, the combustibles that the late Pleistocene extinctions had liberated, the late Anthropocene would again corral, sending them into the gullets of livestock. In practice, that colonization first required the pacification and relocation of the Apaches. Not until the indigenes were suppressed did livestock overrun the ranges. Eerily, the year of Geronimo’s surrender, 1886, saw the last great breakout of fire in the Chiricahuas. Free-burning flame had less to feed on, and starved. Even before the formal policies of suppression, the mountains had entered an era of fire famine.

Of course the movement of imperial people into and out of the region – what anthropologist Edward Spicer in a larger context famously described as “cycles of conquest” - had to interact with the cycles of climate to yield the region’s chronicle of fire. And that is precisely the point: it is the interaction of these two grand rhythms, one of wetting and dry, and one of human coming and going, that the region’s fire records testify to. There is little dispute that massive overgrazing beginning in the 1880s coincided with a monumental drought in 1891 to drive the high grasslands and forest savannas into collapse; and by destroying surface combustibles, this one-two punch knocked fire out of the biota. It was, however, the removal of the Apache that allowed for the wholesale reintroduction of grazers. The extant fire regime received a triple blow: one from climate, one from fuels, and one from ignition sources. Two of the three were the outcome of people.

The chronicle of fire in the Chiricahuas has not only been written by Pacific warm water pools, Hadley Cells, and monsoons, but also by the vicissitudes of human history.

On all these counts controversy has flared, and it typically pivots on how much agency to grant humans. The critics claim the hard, high ground of science, dismissing outright appeals for human agency or herding them into disciplinary reservations where they are fed the lean rations of anecdote. Climate change, not spears and torches, must have driven megafauna over an evolutionary cliff. Climate change, not longhorns and shovels, must be responsible for squeezing fire out of mountain and grassland. Behind the conviction lies an insistence that one or the other cause must dominate. …

But… the numbers generated from tree-ring scars are not simple “proxies” of climate but indices of people and climate interacting in complex ways. That muddies not only the chronologies but the epistemological status of fire science, not to mention its funding. And not least, perhaps, is that old yearning for an Unmoved Mover. If people have shaped everything, there is no escape from our postmodern selves. …

Indeed there is not. As highly evolved as we like to think we are, humanity is as much a product of nature as dung beetles. And part of our natural role is to be Masters of Fire. As Pyne points out pithily, “probably Homo habilis understood these dynamics.” Proto-humans had mastered fire long before Homo sapiens appeared on the scene (~200,000 years ago in Africa). When sapient hominids first entered North America approximately 13,000 years ago, we brought along a few hundred thousand years of practice and experience in setting whole landscapes on fire.

Of course, by then anthropogenic fire was marbled with nuance; we had a cornucopia of purposes and techniques that lay behind the burning, and they all had something to do with human survival and well-being — industrial fire is a very ancient undertaking.

And as much as our modern priests of enviro sanctity preach and pontificate about the Original Sin of human manipulation of Nature, and our badge-wearing, high-booted soldiers of that religion demand purity of ignition (lightning only), the Chiricahuas resist the imaginary catechism. Anthropogenic fire has returned, in the form of transient-set fires:

But the most interesting reintroduction is occurring outside official channels altogether. The Chiricahuas and neighboring Peloncillas have reestablished themselves as a portal for unauthorized human traffic across the international border – a veritable Mexican monsoon of border-crossers who carry fire as much as contraband. The variety and geography of the burns eerily echo the old Apache suite: abandoned cooking and warming fires, accidental fires, fires set as distress signals, fires kindled to divert attention away from illegal activities. The Border Patrol has proved no more effective in stemming such ignitions than the Forest Service was, over the long run, with lightning. In the end, both have proved unable to shut down the fires, and perhaps are unwilling to do so at the costs demanded. Officials can’t turn off lightning, and they can’t control people who are by definition renegades and “illegals.” Fire has returned. The restored rhythms are restoring the old rhymes. …

Such is the reality of fire in the Chiricahuas. It is not yet recognized by fire science, which has achieved much of its clarity by excising people just as it has omitted their fires. Take away human agency and only natural causes remain, and with only natural causes, the sole medium of research must fall to natural science. Only by knowing the proper mechanisms – linked in a chain of causality – can we devise suitable responses; only natural science can track that succession of attribution; and only such sciences can suitably translate the explicated chain of consequences into a chain of command by which research informs and management applies. …

It may be only a question of time before such realizations cross the border that divides the two cultures of science and humanities in such numbers that they force fire scholarship to accommodate people as it has nature.

The Sky Islands have been home to people for the entire Anthropocene (nee Holocene). People have reordered the botanicals (and zoologicals) over thousands of years. There is no going back to pre-human days, even if we wanted too (despite the flaming rhetoric from the modern high priests of human sacrifice). We have to play the cards we have been dealt (by ourselves to ourselves).

Philosophically and practically, forest and fire science and management must embrace the real history of our landscapes. The current conceit that humanity is a visitor to this planet, like a foreign guest who has overstayed his welcome, must be cast into the burn barrel. We are by, of, and for Nature. Always have been. It’s time we face our responsibilities like adults and reinstate human stewardship of our landscapes. Mother Nature needs us; that’s why She created us in the first place.