Tucson fire sites Northern New Mexico fire sites Southern New Mexico fire sites Northern Arizona fire sites Southeastern Arizona fire sites Western New Mexico fire sites El Malpais, New Mexico fire sites

Laboratory of Tree-Ring Research

Southwest Fire Tree-Ring Sites
SW fire sites
Click on any shaded area to see some fire graphs of those sites (or hit the direct links below).

Tucson     Northern New Mexico     El Malpais, NM

Southern New Mexico     Northern Arizona

Southeastern Arizona     Western New Mexico

SW summary fire graph
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