“There are always flowers for those who want to see them.” — Henri Matisse

In May of 1999, the “Juniper Complex Fire” burned 13,894 acres of Joshua trees and blackbrush within Joshua Tree National Park. Desert wildfires of such magnitude were exceptionally rare prior to this, otherwise usually limited to less than a few acres.

Unfortunately today they are increasingly common and larger. Two things changed. One was the introduction of non-native annual grasses by cattle ranchers in the late 19^th and early 20^th century. Cheatgrass (Bromus tectorum), red brome (Bromus rubens), and Mediterranean split-grass (Schismus barbatus) were the main grass weeds. Unlike native desert annuals, which after blooming and then going to seed typically disarticulate and blow away with the fall winds, these invasive grasses are persistent after completing their life cycle, leaving their dead stems rooted in the ground, accumulating fuel to carry fires.

The second thing was only discovered just shy of two decades ago. Dr. Edith Allen and her students from UC Riverside discovered that these grasses reached high enough densities to fuel massive desert wildfires because they were being “fertilized” by the nitrogen-rich smog wafting into the desert from the Los Angeles Basin’s clogged freeways and busy ports. Dr. Allen once equated the amount of annual smog-based nitrogen landing on the desert as very similar to the amount of nitrogen farmers spread across their fields each year to grow corn. Without that added nitrogen, these grasses mainly occurred as clumps at the leeward bases of perennial desert plants where, after decades and in some cases centuries (creosote bushes) of accumulated organic material, there were “islands of fertility.” Some years, when desert rainfall is below average, because the accumulation of organic material can hold on to what little water is available, those islands of fertility are the only places to find wildflower displays. Without that added nitrogen, the invasive grasses are sparse and lack the fuel to carry fires across a desert landscape. The grasses needed to be fertilized to create fuels dense enough to feed wildfires, whereas native desert plants evolved in a low nitrogen environment and so have no need for or response to the added fertilizer.

Our intrepid band of desert naturalists, members of our “Community Science Collaborative,” hiked across one edge of that Juniper Complex Fire “footprint” this past week. Twenty-four years after the fire was extinguished, the edge of that fire line is still clearly visible. On one side, where the fire never burned, silver cholla, barrel cactus, Englemann’s and Mojave mound hedgehog cacti, cushion foxtail cactus, Muller’s live oaks, blackbrush, California junipers, “old growth” Parry’s nolina with trunks nearly a meter thick, and Joshua trees dominated. On the side that burned there was just dried grass, Acton’s brittlebush (in bloom), scattered live oaks, and even more widely scattered nolina. No cactus, Joshua trees, junipers, or blackbrush, except for just a few patches right along the old road and current trail leading to the abandoned Lost Horse Mine. We guessed that the lack of vegetation on the road kept the fire from getting so hot to kill those plants or their seeds. If the desert is restoring itself, it is a very slow process, too slow to be measured by average human lifespans.

Outside the burn’s footprint there were large flocks of sparrows — lark, white-crowned, and black-throated. There were also California thrashers, a red-tailed hawk, ladder-backed woodpeckers, and cactus and rock wrens. Inside that footprint there were only the ever-present metallic “twinks” of rock wrens. There was another stark difference between life inside and outside the wildfire’s footprint. The density of lizards was easily two to three times greater in areas that had burned 24 years ago. To be clear, it wasn’t all lizards, but at least for side-blotched and desert spiny lizards there was a clearly higher abundance inside the burn footprint. For such a noticeable difference there would need to be either more food, better conditions for thermoregulation, and/or fewer predators inside the burn zone. Someone unfamiliar with deserts might also argue that the lack of woody vegetation inside the burn footprint just made it easier to see lizards, that the densities might not be different at all. But the vast majority of lizards were perched on large boulders, easily seen whether or not there was woody vegetation nearby.

On another of our regularly surveyed trails, the Spitler Peak trail, the “Mountain Fire” burned the entire site in 2013, just a week after I had completed my first lizard survey there. I expected that the 2014 survey would show that the lizards had been decimated, but I was wrong. That year and for the next half a dozen years, the lizards, especially side-blotched and western fence lizards, were abundant and more so each year. Granite spiny and southern sagebrush lizards didn’t appear to change at all. The Spitler Peak Trail cuts through a montane chaparral habitat, vegetation that evolved to survive and thrive after fires. Immediately and for 3-5 years after the fire, the open spaces were filled with specialized, fire-following wildflowers.

The wildflowers in Joshua Tree have had no such history to adapt to and thrive in response to the disturbance and opportunities provided by wildfires. The Spitler Peak trail, immediately following the fire was more open, sunnier, with more pollinating insects, more seed-eating insects than before the fire. So, there was more food for lizards and sunnier, exposed boulders for lizards to thermoregulate on. The populations of fence and side-blotched lizards, species that also occur at hotter, lower elevations, are heliothermic, lizards that actively “sun bathe” in order to maintain their preferred body temperature. These species benefited from the fire opening up new perching sites. They probably also benefited from more insects to forage on. Southern sagebrush and granite spiny lizards occur at much higher and cooler elevations, and so at the elevations available along the Spitler Peak trail are more apt to be thermal conformers, happy to live at temperatures in the shade of trees, Although, at those cooler, higher elevations, they too become heliothermic. Now, ten years after the Mountain Fire, the habitat is well on its way to being fully restored. The only things missing are the conifers. There were five species of conifers present before the fire; only a handful of Coulter pines remain.

I suspect that for the side-blotched and desert spiny lizards along the +/- 5,000’ Lost Horse Mine trail in Joshua Tree National Park, the Juniper Complex fire opened up new heliothermic opportunities. Both species also live at much lower, hotter elevations, so the fire would have provided more opportunities to sun bathe to maintain their preferred, warmer temperatures. As arguably negative as the Juniper Fire was for most high-elevation Mojave Desert flora and fauna, it seemed to open the door for some lower elevation species to exploit higher elevations. As those lower elevations become increasingly warmer and drier and inhospitable, those that can exploit higher elevations may have an edge for survival. A silver lining, or in the words of Henri Matisse, a flower.

 Nullius in verba      

Go outside, tip your hat to a chuckwalla (and a cactus), think like a mountain, and be safe.