Looking out into the desert, it amazed me that I had never seen a "forest" such as this in my lifetime. In every forest, there are usually a fair number of ground covers and almost always a shrub and small to mid-size tree level. After noticing all of this, the tall "trees" were these mostly vertical, green columns, some with extra "arms" and some without; the Saguaro cactus (Carnegiea gigantea). Most other forests have trees that formed some kind of canopy. The Sonoran Desert "forests" have no canopy, so you can see a lot more from a distance.
This landscape has the similarities to other forests of the world because of its diversity of flora and fauna. I saw a large selection of birds, many similar to those I see in the Pacific Northwest, but some that only prefer the dry, warm to hot days and cool to cold nights of the deserts.
There are many insects and arachnids, that feed the large diversity of reptiles. There are many of your more common North American mammals here as well. Even riparian oases survive in this harsh climate. These oases have some of the last species of amphibians on the planet as well as a variety of fish species.
I have seen the variety of desert landscapes across the southwestern US, but this one just blew me away!