Arizona oak savanna

With Xmas behind, we are now exploring the oak savannas of the southwestern U.S. Yesterday we visited an area on the east side of Saguaro National Park. We approached the area through part of the Coronado National Forest, a huge region in southeastern Arizona east of Tucson. A sixteen mile drive in a four-wheel drive vehicle on a dirt road took us to Miller's Creek, one of the jumping off sites for the Arizona Trail, a grand hiking trail that runs the whole length (N/S) of Arizona.

We started out in what is called Sonoran Desert (lots of saguaro cactuses), climbed gradually through desert grassland, and then reached the savanna at about 4000 feet altitude. The oaks were primarily Emory oak (Quercus emoryi), an evergreen species that has a characteristic open-grown form.


There were also several other oak species growing as low shrubs. According to Ffoliott and Gottfried (Plant communities and associations of Arizona), other oak species found in this vegetation type are Arizona white, Mexican blue, gray, silverleaf, and occasionally netleaf and Toumey oaks. All of these are evergreen, and most of them lack the characteristic oak leaf shape that we know from the Midwest.

The term "oak woodland" is more commonly used here than "oak savanna." They are sometimes called "encinal woodlands" from the Spanish word meaning "oak". Oak woodlands range from 4000 to 6500 feet in altitude (at higher altitudes are various types of pine/conifer forests). The climate is of course cooler than that of the desert, with more rainfall, and a lot of the rain comes in summer "monsoons". There is also occasional snow, and we found a few snow patches remaining from a heavy storm that had occurred earlier in the week.

The flora, of course, is completely different from what we know from the Midwest. It will be a challenge to identify even the oaks, let alone all of the shrubs, grasses, and forbs.

More later.