Unexpectedly ancient
I’ve posted this photo a few times. I’m posting it again now. What jumps out at you when you look at it? The light? The alpenglow on Clark Mountain in the background? The rocks, the Joshua trees? The blurry cholla?
Right now, for me, it’s the least conspicuous aspect of this photo that’s blazing out at me, and I am staggered.
See the dark gray bushes in the foreground, among the Joshua trees? That’s blackbrush, Coleogyne ramosissima, and I don’t think, after tonight, that I’ll ever look at it — or the Mojave — the same way again.
I’m working on a piece for the Desert Protective Council intended to convey the notion that the desert is not a renewable resource. People call paving desert wildlands for solar “renewable energy.” I’ve become increasingly persuaded that’s deceptive terminology, because while the sun may come up every morning the desert landscape that gets bladed to install industrial facilities that make solar power is actually rather fragile and very slow to grow back. And so I’ve been doing a little background research before drafting. There are certain things I intended to mention. The 12,000-year-old creosote clone in Johnson Valley? Check. Cryptobiotic crusts that grow an inch a century, and without which the desert would blow away? Check. I was working on finding some stats about Yucca schidigera, which grows in clumps that take centuries to form — there are 1,000+-year-old Yucca schidigera clumps all through the Mojave Preserve, and leafing through another few old scientific papers I thought I might want to look at, and then I saw a paper entitled Dynamics of Mojave Desert Shrub Assemblages in the Panamint Mountains, California by Robert H. Webb, John W. Steiger, and Raymond M. Turner which was published in Ecology, June 1987.
It mentioned blackbrush.
Webb, Steiger and Turner did a study of disturbed areas west of Death Valley. Some had been disturbed by human activity in the late 19th century, some by debris flows in the last couple thousand years, and some by debris flows of Pleistocene age. They determined the rate at which desert plants recolonize disturbed areas. They found that Coleogyne is very slow to revegetate areas from which it had been stripped.
Now as it happens, I’ve written about blackbrush recently in this very context, in a new Joshua tree book chapter I took to my writers’ group last week. Here’s what I said:
A stand of native blackbrush will take at least fifty years, and probably far longer, to recover from wildfire. That’s assuming there are no fires afterward, and there will be.
It’s a scary image, one literally seared into my brain. In 1997 I went to Bulldog Canyon, Utah, where a fire had knocked down a thick stand of blackbruush and Joshua trees a decade earlier. The difference between burned and unburned was stark after a decade. Where the land had not burned, blackbrush covered the land in an almost solid carpet. Where the fire had been, there was no blackbrush even after a decade.
This is important for a few reasons, the nearest to my heart being that blackbrush is the most common nurse plant for Joshua trees, at least in the Mojave. Blackbrush is pesky to hike through, stiff and ornery and scratchy, and Joshua tree seedlings that germinate under a blackbrush canopy stand a good chance of escaping hungry rabbits and ground squirrels until they’re old enough to fend for themselves. Joshua trees also grow in places dominated by other shrubs, creosote probably blackbrush’s main rival in this regard. More often than not, though, a Joshua tree forest is actually a Joshua tree-blackbrush forest.
So what’s the big deal about reading a paper published a quarter century ago? Just this: it turns out I was off in my estimate of how long it takes blackbrush to regenerate. Way off.
Blackbrush can make nearly solid stands across many square miles of desert. The photo above shows one such, mixed in with a dozen or so other shrubs like Menodora and chollas and a few others. Hiking on Cima Dome is an exercise in getting to know blackbrush. There’s a lot of it there, in some places more than half the plant cover.
Webb, Steiger and Turner found that blackbrush took as much as “tens of thousands of years” — their words — to revegetate up to 20 percent cover in the areas they studied.
That’s one study. Something may have happened to the places Webb, Steiger and Turner examined to slow the growth of blackbrush. So I looked elsewhere. I am still collecting citations for the piece I’m writing. It would seem the consensus is that a thick, Cima Dome-style stand of blackbrush probably takes from 5,000-10,000 years to develop.
That unprepossessing, inconspicuous, actually kind of ugly plant in the photo is the base of a very specific ecosystem that may have taken longer to develop than the whole span of human history.
This may be hard to grasp, for for those of us raised on 19th-century ecological notions such as succession and climax forests and such. So let me put it this way:
Find the oldest coast redwood forest on earth, with trees three hundred feet tall and thirty feet thick at the base, some of them 2,000 years old. Then plat out a few square miles of the White Mountains’s bristlecone pine groves, home of the Methuselah tree and its ancient cohort, ranging up to twice as old as the redwoods. Then pick a random piece of Cima Dome, a couple miles in each direction, full of unprepossessing blackbrush.
Chainsaw all three. Bulldoze it all flat. Leave only stumps flush with the ground. Then let them all grow back at their own pace. When the new redwoods and bristlecones are considerably older than the ancient ones we have now, the blackbrush may still not be more than about halfway recovered.
It’s a blackbrush forest out there, and it grows inconsequential, short-lived Joshua trees out of it here and there, ephemeral companions, banacles on a whale. Though individual blackbrush plants in a stand may not be particularly old, a solid stand of blackbrush is an astonishingly ancient community.
This is how Webb, Steiger and Turner said it:
“Time span for [vegetative] recovery may be longer than past periods of climatic and geomorphic stability.”
They’re talking geological epochs here. They’re talking the blackbrush community beginning when there were standing lakes in the Mojave with sabertooth cats and ground sloths drinking out of them.
And we see it as less valuable than a few megawatts of power to run our swimming pool filters.



