Saguaro National Park protects almost 92,000 acres of the northern Sonoran Desert. Established as a National Monument by Herbert Hoover in the waning days of his disastrous presidency, it was upgraded to a National Park by Congress in 1994, part of a robust legacy of desert conservation during the presidency of Bill Clinton. Of the Park’s 92,000 acres, 71,000 are federally designated Wilderness.

The Park comprises two distinct units on the eastern and western edges of Tucson, Arizona. While both units contain the same general ingredients of desert grassland and variously vegetated transition zones climbing the slopes of mountain ranges, they have markedly different flavors. To the east, Rincon Mountain District contains a true Sky Island, a mountain range high enough and cool enough to cradle habitat remnants of ecosystems—trapped above warming valley floors as the Ice Age glaciers retreated—usually found much farther north. To the west, Tucson Mountain District, smaller and lower, feels more iconically like desert, with dramatic, virtually bare, mountains rising sharply from flats and valleys.

(more…)