Laboratory of Tree-Ring Research
Southwest Fire Tree-Ring Sites
Click on any shaded area to see some fire graphs of those sites (or hit the direct links below).
This summary graph shows a relatively consistent frequency of fire occurrence prior to 1900 (the "presettlement era") across the 63 fire sites of the Southwest. Then, fire frequency dramatically decreased at about beginning 1900.
Hypothesized reasons for the change in fire frequency at about 1900 are explained in these articles:
- Swetnam, T.W. and C.H. Baisan. 1996. Historical fire regime patterns in the southwestern United States sense AD 1700. Pp. 11-31 in Fire Effects in Southwestern Forests. USDA Forest Service General Technical Report RM-GTR-286. This paper summarizes the fire history patterns from the entire network of 63 sites across the Southwest.
- Savage, M. and T.W. Swetnam. 1990. Early 19th-century fire decline following sheep pasturing in a Navajo ponderosa pine forest. Ecology 71:2374-2378. This paper notes of the role of sheep grazing for changing natural fire patterns at a site on the Arizona-New Mexico border. Sheep herding occurred throughout the Southwest during the late 1800s, and the effect of sheep on fire patterns and behavior can be inferred for most forests throughout the region.
Laboratory of Tree-Ring Research, University of Arizona
Tucson, Arizona 85721 USA
Main Office: (520) 621-1608, Fax: (520) 621-8229
Comments to Paul Sheppard: sheppard @ ltrr.arizona.edu
Copyright © 2000-2013, Laboratory of Tree-Ring Research, University of Arizona
Revised April, 2013