Joshua Tree NP - a Botanical Viewpoint

Living in the Sonoran Desert south of Tucson, AZ, for the past 7 years has provided quite an education to someone who has lived most of her life in the eastern US.  First, I now understand (TOTALLY) that globes portraying brown on the western part of the US and green on the Eastern, are based on reality.  Or, at least, so it would seem to many of us transplants. But, over time you find that vegetation, mostly of the "native plants" variety, can provide beautiful gardens and landscapes wherever you are.  The trick, if there is one, is to "go with the flow" and not try to fool Mother Nature!

So I looked forward to this RV trip, visiting national parks and, sometimes, more formal botanical areas, to continue my flora education.  Arriving at Joshua Tree yesterday, I knew it contained portions of two desert biomes (Sonoran and Mojave), but touring this NP provides outstanding vistas that accentuate "where you are". 

The Sonoran Desert (SD) around Tucson receives about 12 inches of rainfall annually.  However, here in JTNP, rainfall averages are closer to 4 inches annually.  So, you cannot expect to see the same landscape in both locations. Elevation changes around the southwest can quickly introduce you to climate changes (some like it hot, others flourish in higher, cooler environs). And each desert has some "signature plants" like palo verde trees in the Sonoran, and the Joshua Tree in the Mojave.  And, other desert plant families, such as cacti species, may be found in both.  

At JTNP elevation defines these deserts.  The Joshua Tree - not really a tree, but a member of the agave family, and closely related to grasses - exists and thrives in the cooler higher Mojave Desert.  Cholla cactus (certain species), Palo Verde trees and ocotillos prefer the Sonoran.  And, the creosote, a great drought survivor, inhabits either desert.  And, as pictured below, we saw "forests" of these plants - with creosote seeming to provide a transitional zone.

Prickly pear and cholla cacti species are prevalent in both deserts in this NP.  But, there are differences.  The same species may be smaller here than in Tucson (lower rainfall?), like this "beaver tail". 

 

Or, this one with the common name of "grandfather " prickly pear due to the numbers of spine giving it a "white - haired appearance, is one not common to the Tucson area, but was found blooming around Joshua Trees. 



And then there are the PALM TREES - 

Another topic which is exciting and also a unexpected at this park are the number of oases within the boundaries of JTNP.  Fan Palm trees still can be seen at some of the remaining oasis sites in lower elevations. These springs and permanent sources of water have been cherished by people for centuries (or more), supporting ranches and mining operations during more recent history.  Use of water has lowered the water table to the point that many of these majestic giants (the Fan Palms) are now disappearing.  One oasis we visited in now considered a "conservation site" and the NPS is supplying supplemental water. 

Shown is the Oasis of Mara (conservation project) near 29 Palms, CA.

And - how or why are there oases at this park?  I found the answer is tectonic activity.  Several fault lines are running beneath JTNP and one result is that when groundwater hits a fault area, it will be pushed toward the surface!  Never did I know geology could be included in a flora discussion, but here it is!