Table 4. Examples of historical tree densities in frequent-fire forests, and the magnitude that tree densities have increased in contemporary forests above historical densities. Only studies that included dead wood in tree-density reconstructions are included, except for Habeck (1990), who corroborated results using historical land-survey records. Location Major species† Trees/ha‡ × increase Reference Cascade Mountains, WA pipo, psme 27–68 3§ Harrod et al. 1999 Pattee Canyon, MT pipo, laoc 93–172 3–8 Habeck 1990 Mt. Trumbull, AZ pipo, quga, juos 62 22 Waltz et al. 2003 Grand Canyon, AZ pipo, quga 140–246 3–7 Fulé et al. 2002 North Kaibab Plateau, AZ pipo, quga 138 5 Covington and Moore 1994 San Francisco Peaks, AZ pipo, mc 52 25 Heinlein et al. 2005 Near Flagstaff, AZ pipo, quga 148 9 Fulé et al. 1997 Near Flagstaff, AZ pipo 60 52 Mast et al. 1999 † Major species recorded in historical forests: pipo = Pinus ponderosa, psme = Pseudotsuga menziesii, laoc = Larix occidentalis, quga = Quercus gambelii, juos = Juniperus osteosperma, mc = mixed conifer. ‡ Total tree density for all species. All studies, except Harrod et al. (1999) who reconstructed tree density in the year 1935, reconstructed tree density to years in the late 1800s, usually the time of the last recorded surface fire. § Information on tree-density increases in this study was provided for one plant association that had a historical tree density of 45/ha.