The far southwest’s Mojave desert is a gorgeous, if hot and dry, ecosystem home to, among other things, the Joshua Tree National Park. But in a recent post on the amazing travel blog “Adventure Journal”, Cally Carswell shares some pressing news about climate change, the impact it is having on the Joshua Trees, and the implications it has on plant migratory patterns. Carswell begins by reminding us that in just one year, the blooming Joshua Trees look radically different. Last spring, they were an incredible sight. This year, though, something is amiss- the trees, which usually bloom together, are not nearly as beautiful.
According to United States Geological Survey (USGS) ecologist Todd Esque, has some ideas as to why the tree population seems so sparse. It’s simple really, the leading thought appears to be that the Joshua Tree population is beginning to shift northward, following the same patterns at the changing climate. The older trees are obviously staying put, but the newer blossoming plants are being “flung out” to more forgiving climates. Esque tells us that is fairly obvious to even the casual observer, because its all happening at the fringes of the desert that give way to the Great Basin; you can see the famed Joshua Trees fade to sagebrush.
Thanks to the paleo-record, we have been able to see that, historically, plants have been able to migrate, and it’s of increasing importance for Joshua Trees to do so in order to ensure their own survival. Non-native species of grass are rapidly spreading fires that destroy the trees, and the increasingly arid desert could render 90% of the Joshua Tree home uninhabitable within the century.
A troubling study though, hypothesizes that the tree may not be able to move quickly enough to avoid further decimation of it’s population. The principal cause of this failure is that Northotheriops, or the Shasta Ground Sloth was one of the principal distributors of Joshua Tree seed. However, the sloth is now (obviously) extinct, and populations of organisms such as squirrels may not be able to cover that great a distance in that time period. However, this is all hypothesization, Esque says as he brings us back to reality. After all, while the idea surround the Shasta Land Sloth makes sense, we can never know for sure because we don’t know the actual range of that creature. Also, there’s no evidence that shows how quickly Joshua Trees can move, if at all. Esque muses that they may have a “static front”, that is, a population that doesn’t move. While it is constantly casting out young trees, periodic droughts wreck the population, inhibiting its growth.
There’s a lot of questions surrounding this, but Esque says we’re still witnessing a remarkable occurrence.
Anyway, get out to California, and see those trees.