It's been an incredible spring for Joshua trees in the Mojave Desert and throughout the Southwest. The strange and gangly desert forest is in the last stages of an unusually rich and widespread bloom. Some biologists say they've never seen such a spectacular year, but they don't agree on why it's happening.
To check out the bloom, I drove up to the Mojave National Preserve with David Lamfrom, a plant biologist from back East who now works for the National Parks Conservation Association. Once inside the preserve, about 160 miles northeast of Los Angeles, we headed to a highland area called Cima Dome.
"We're heading up to the largest Joshua tree forest on earth, which is experiencing the greatest bloom that, arguably, anybody's ever seen," Lamfrom said. "In years past, I would be doing what I'm doing now and I would see one single tree blooming."
But now, every tree looks like it's in flower, with waxy clusters of cream-colored and pale green flowers erupting from the dark green fronds at the end of the trees' gnarled arms.
"There's insects hiding all in this. You see?" Lamfrom asks as he pulls back the petals of a flower cluster. "Can you see all this in here? Like little flies, little bugs.
It's kind of a little fountain of life. And even in a dry place like the desert, these plants are putting off so much moisture that everybody's coming in to get some pollen."
This year's massive bloom has sparked a debate about what's causing it. Lamfrom thinks it's because weather conditions the past year have been just right, with late summer rains and cool winter temperatures. But some other scientists think there's more to it.
Desert biologist Jim Cornett has been studying Joshua trees since the 1980s. He says old and young trees usually don't bloom at the same time. This year, he says, it's different.
"Very old trees that were starting to fall apartothey were blooming," he observes. "And then a lot of trees that had never bloomed before were blooming this year."
Cornett says changes in the regional climate might have something to do with the widespread Joshua tree bloom.
"My working hypothesis is that these trees are being highly stressed as a result of two serious droughts in a row and I think that that stress has caused the trees to reproduce en masse throughout their range."
In other words, the trees might be making a last-gasp attempt to produce and spread seeds and pollen before they die. Cornett also says he sees signs that the Joshua tree's range is shifting due to climate change.
But another biologist who has spent decades in the Eastern Mojave says he's not convinced that the bloom is as rare as others say it is or that it's so easy to explain.
Jim Andre is director of UC Riverside's Sweeney Granite Mountains Desert Research Institute. He says there's just not enough evidence to say that this year's bloom is related to late summer rains or stress from drought.
"Why are the Joshua trees flowering?" he says. "There is no simple answer, where we can turn to empirical data."
So the why is unknownofor now. But the what, when and where? With the bloom happening now in the Mojave, David Lamfrom says he's going to enjoy the show while it lasts.
"I think all of us out here know that we're being treated to something that we may never see again," he says.
The bloom is expected to continue maybe through the end of April.