Wildfires. However big or small, the aftermath always looks devastating. This is even truer after a wildfire burned near the California-Nevada, which has ravaged parts of the Mojave National Preserve’s famed Joshua tree forests.
Experts have expressed their concerns about the future of the tree if the fire keeps coming—some even outright pessimistic.
It’s not without reason, though, since the massive blaze can potentially change the fragile desert ecosystem forever.
According to Debra Hughson, the preserve’s deputy superintendent, the recent 94,000-acre York Fire has burned the trees and other plant species, leaving behind a permanent reminder on the preserve’s landscape.
“They burn real well. You have just barren, blackened soil, and there’s nothing left but ashes and scraggly Joshua tree stumps sticking up. That doesn’t come back. It’s gone forever,” Hughson said.
The unforgiving York Fire
York Fire is now the largest to burn through the eastern Mojave in recorded history. Before, there was the 71,000-acre Hackberry complex fire of 2005 which had left an earlier permanent mark on a delicate ecosystem already strained by invasive species and the warming earth.
Invasive species which have been plaguing the Joshua trees will get worse as the climate warms more. According to a plant sciences professor Justin M. Valliere who has studied what is known as the invasive grass cycle.
After fires, landscapes like the Mojave can become more vulnerable to invasive species. The invasive plants then grow faster and promote more fires, continuing a positive feedback loop.
“Invasive grasses in the Mojave Desert are completely altering the fire regime there and leading to more frequent fires,” Valliere said.
Now, the fire has mostly burned inside the preserve’s boundaries and scorched some parts of the Avi Kwa Ame National Monument. Park officials said that the fire had been 93% contained on Saturday 5th August.
Putting off the fire on this preserve isn’t as easy as spraying extinguishers to small fire. Crews have had to balance their firefighting efforts with the need to not disrupt the sensitive desert ecosystem—the home to hundreds of rare plant species like the Joshua tree and the threatened desert tortoise.
Therefore, the crews have avoided the use of heavy equipment like bulldozers while building fire lines.
A dark future for the trees
Like many desert plant species, Joshua trees can’t deal well with wildfires. “They go up like they’re soaked in diesel fuel,” Hughson said. The only chance for the trees to survive, according to the National Park Service, is if the fire only reaches the top third of the plant.
Lynn Sweet, an assistant research ecologist who studies Joshua trees, said that in some cases, the trees can actually survive fires. Unfortunately, on a whole, they haven’t adapted to wildfires. “They have a really high mortality during wildfires,” Sweet said.
There are nurse shrubs such as blackbrush which have helped new Joshua trees grow. Sadly, the fire has wiped out large areas of those nurse plants, as well, which Sweet said only reduces the chances that those Joshua trees can recover.
Officials at the preserve don’t know exactly how much of the Joshua tree forest has been burned by the latest fire.
For now, they believe it has caused a similar level of devastation as that of the Dome Fire, which scorched the preserve in 2020 and burned an estimated 1.3 million Joshua trees—or about one-quarter of the region’s contiguous Joshua tree forest.
Some Joshua trees experts have been discouraged after seeing the devastation, like James Cornett, an ecologist who specializes in the species.
“Joshua trees are already in a state of decline because of global warming and increasing frequency of drought. And then on top of that, you throw on a fire like the York fire, and these trees are not likely to recover in our lifetime.
“In fact, I can say with the utmost certainty that the areas that burn — whether it’s Joshua trees or other plants — will never look the same in the next couple of generations, if not longer,” Cornett said.
Can’t humans help?
When a great loss such as this occurs, a question asks whether we humans can help restore the trees.
The short answer is, although possible, the efforts are mostly unsuccessful. According to Ashley Hemmers, a tribal administrator for the Fort Mojave Tribe, whose ancestors have lived for centuries in the region, when humans try to help foster regrowth of burned or damaged Joshua trees, it’s a long, fraught process.
“It’s a slow-growth tree. Even if we were to revitalize and restore, which we do … we won’t see the fruits of that for a whole lifetime — if we’re even able to,” Hemmers said.
Hughson added that the literature on vegetation restoration in the Mojave Desert “is a tale of failed experiments. In fact, recovery efforts to replant Joshua trees after the Dome fire had not been particularly successful.
The once dense Joshua tree forest burned by the Dome Fire has started to transition to a grassier landscape. Although a small number of the Joshua trees in that area did manage to resprout from unburned roots, Hughson said, “it’s not a juniper tree forest, nor will it ever be again.”
There have been efforts which focus on replanting the trees in high-elevation areas, where Joshua trees are likely to have a better chance at survival as global warming makes the desert climate even harsher. Still, many believe that the once-full forests will probably never return.
The changing of the planet
Supervisory park ranger for the Mojave National Preserve Sierra Willoughby said that the real challenge with these trees is that the forests evolved when giant ground sloth was still around in North America.
The sloth, which went extinct around 10,000 years ago, was once the primary organism that helped spread Joshua tree seeds, through their droppings.
“These are like relic forests. The only things spreading seeds now are like pack rats and other rodents,” Willoughby said. And while those animals do help a little, they don’t spread seeds nearly as widely as the giant ground sloth once did.
Will the trees’ fate end up like the giant ground sloth? Nobody wants it, of course, but the reality is that the ecosystem has changed.
“It’s not going to be what it used to be. It’s going to be something new and different. Overall, it will be a more impoverished ecosystem, less biodiversity, less nice overall. But this is a pattern that we’re seeing globally with fairly global rapid change. We’re just part of it,” Hughson said.
Cornett added that the bleak outcome is unavoidable in today’s time. “It’s beyond their physiological capabilities to compensate for these new burdens. And of course, fire is the most dramatic burden that they’re facing now,” Cornett said.
Silver lining in the cloud
Although the news about the trees is glum, there’s one piece of good news that we can get from the York fire: it has mostly managed to avoid the critical habitat of the threatened desert tortoise.
“We’re thinking and hoping that most of the desert tortoise habitat was unscathed and that most of the desert tortoise are OK,” Hughson said.
Most of the effects to the tortoise population from the fire are likely to come from motor vehicles and large equipment responding to the fire, Hughson said. That’s the reason why preserve officials have been careful and have implemented a 25-mph speed limit for all vehicles operating near those habitat areas.
Other than that, some biologists have come out in the field and moved tortoises off the road and guided vehicles. That way, the tortoises have minimal chances of being killed.
sources
https://phys.org/news/2023-08-ravaged-mojave-famed-joshua-trees.html
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