Riding in the desert is very different. There are no soft landings because there is very little organic material in the soil, and almost all the plants have sharp things that puncture your skin. Your options when you go OTB are usually limited to rocks, hard ground, cactus or thorny plants like acacias. If you ride in an environment where crashing is part of learning and a common occurrence, you will want to modify your style and be less aggressive. You don't want to ruin your visit by spending a half-day in an emergency room and going home with a cast.
Many mountain biking visitors come to the desert full of confidence about their riding skills.
It's a good idea to take it easy, especially on the first couple of rides, and enjoy the scenery. If you feel the need for speed, head for a road and hammer to your heart's content.