Adapted from Jim Conrad's online book A Birding Trip through Mexico; This excerpt from "The Pine Forest of Lake Arareko" near Copper Canyon
ARIZONA PINES
It's so quiet. The mixed-species flock forming a bubble of birdsong around my tent at dawn continues drifting through the little valley just below but, here on the rocky ridge near my tent, even though sunlight speckles the forest floor and wind sighs among the Arizona Pines' boughs, the solitude is nearly as intense as among Samalayuca's dunes at dusk.

In fact, ecologically, this forest strikes me as similar to a desert. The mere facts that it consists of a single species of tree and that there are few wildflowers and grasses on the forest floor indicate that the environment here is harsh. If it were more hospitable, several tree species would be competing for space, and undergrowth would be dense. But here I can walk unimpeded below the pines, as if I were in a park.

These Arizona Pines are very closely related to the Pondorosa Pines so common in the mountains of much of western North America. In fact, earlier Arizona Pines were considered to be a variety of Pondorosa Pine, a variety specializing in high-elevation canyons of Mexico's Western Sierra Madres. The variety was known scientifically as Pinus ponderosa var. arizonica. Now most specialists regard this tree as a distinct species called Pinus arizonica, the "Arizona Pine," despite the fact that only a small part of its distribution extends into Arizona. For my part I'd be glad to call it the Tarahumara Pine.

You can read about Arizona Pines and see a map showing their distribution along with the Pondorosa Pine here.