Stretching from just southwest of Flagstaff to the White Mountains of eastern Arizona, the Mogollon Rim [map] marks the southern edge of the Colorado Plateau in Arizona. The long escarpment, thousands of feet high in some areas, extends for nearly 200 miles across central Arizona. Average elevation of this undulating rim and plateau country is about 7000 feet.
The Mogollon Rim is known for its stands of ponderosa pine, which comprise the largest ponderosa pine forest in the United States. Much of the gentle plateau country just north of the rim has been heavily logged. Timber production was a major part of the region's economy earlier this century, helping to establish a few towns in and near the vast pine forests of the area. Today, the United States Forest Service manages much of the region as part of four national forests: the Kaibab, Coconino, Sitgreaves, and Apache National Forests.
A paleoecological study at Potato Lake at 7300 feet atop the rim has been completed by Dr. R. Scott Anderson of Northern Arizona University. Dr. Anderson's results indicate that dramatic changes have occurred in the area's biota over the last 35,000 years. Pollen analysis from cores taken from the lake suggests a varied vegetational history for the site extending back many thousands of years. From 35,000 to 21,000 years ago it appears most of the rim in this area was covered by a mixed-conifer forest, evidence of a climate cooler and wetter than that seen today. From 21,000 to 10,400 years ago a subalpine conifer forest dominated by Englemann spruce surrounded the lake, indicating even colder conditions. Today this spruce is generally found above 10,000 feet at the highest elevations on the Plateau. It appears the lake almost dried up completely about 5000 years ago, as there were few lake sediments represented in the sample for this period. Approximately 3000 years ago the forest surrounding the lake evolved into a community dominated by ponderosa pine, and the area likely looked much like it does today.
One of the major cultural divisions of the prehistoric Southwest is the Mogollon tradition. These people, closely related to the Anasazi, are so named because archaeological remains of this culture were first discovered along the Mogollon Rim. However, the rim country defined the northernmost reaches of this culture, which stretched across the Arizona-New Mexico border, into northern Mexico, south of Anasazi territory. The Mogollon people farmed floodplains and hunted wild game, living in small villages of pueblo dwellings and subterranean kivas. Like other areas of the Colorado Plateau, by 1300 A.D. the Mogollon Rim was abandoned by its prehistoric occupants, whose descendants were most likely incorporated into the modern Pueblo people.
--Researched and written by Shannon Kelly
Restoring Ecosystem Health in Ponderosa Pine Forests of the Southwest. Previous research has established that forests of ponderosa pine in the Southwest were much more open before Euro-American settlement. Restoration of ecosystem structure and reintroduction of fire are necessary for restoring rates of decomposition, nutrient cycling, and net primary production to natural, presettlement levels. The rates of these processes will be higher in an ecosystem that approximates the natural structure and disturbance regime.
Paleobotany and Paleoclimate of the Southern Colorado Plateau. The biota of the Colorado Plateau during the middle (50,000-27,500 B.P.) and late (27,500-14,000 B.P.) Wisconsin time periods was dramatically different from that seen today. Differences were primarily a result of major climate changes associated with the last major glacial period. This site examines the environment of the southern plateau during this time. Adapted by R. Scott Anderson from his journal article.
Anderson, R.S. 1993. A 35,000 year vegetation and climate history from Potato Lake, Mogollon Rim, Arizona. Quaternary Research 40: 351-359.
Hasbargen, J. 1994. A Holocene paleoclimatic and environmental record from Stoneman Lake, Arizona. Quaternary Research 42: 188-196.
Jacobs, B.F. 1983. Past vegetation and climate of the Mogollon Rim area, Arizona. Ph.D. Dissertation, University of Arizona, Tucson, 166 pp.
Whiteside, M.C. 1965. Paleoecological studies of Potato Lake and its environs. Ecology 46: 807-816.