What is the thickest forest in the U.S?

What sort of environment would you have between a desert and a typical forest of the north?

• What sort of environment would you have bewteen a desert and a typical forest of the north? I'm currently writing a book and the characters are first in a forest in the northern hemisphere, and I want them to get into a desert. What do I make them cross to get to the desert? What sort of environment, or geological feature would there be that could be a transition environment bewteen the forest and the desert?

• Answer:

  At least in north America, the transition usually goes from desert to grasslands to open scrub forests of oak and juniper, then to forests of ponderosa pine, then finally aspen and firs. In Arizona, you can find all those transitions going up a single mountain. The setting of your book really depends on the specific route your characters take...as the transition would be quite different in the mid-section of the continent as opposed to travel in the intermountain west, or Appalachia, or the coastal areas.