Category: Ecological Research
Title: Assessing fire regimes on Grand Canyon landscapes with fire-scar and fire-record data
Author: * Fule, P.Z. , * Heinlein, T.A. , * Covington, W.W. , Moore, M.M.
Subject: Ponderosa pine (Pinus ponderosa), Gambel Oak (Quercus gambelii), Kaibab Plateau, Coconino National Forest, Mixed conifer
Abstract: Fire regimes were reconstructed from fire-scarred trees on five large forested study sites (135-810 ha) on the North and South Rims at Grand Canyon National Park. Adequacy of sampling was tested with cumulative sample curves, effectiveness of fire recording on individual trees, tree age data, and the occurrence of 20th Century fires which permitted comparison of fire-scar data with fire-record data, a form of modern calibration for the interpretation of fire-scar results. Fire scars identified all 13 recorded fires 8ha on the study sites since 1924, when record keeping started. Records of fire season and size corresponded well with fire-scar data. We concluded that these methods are highly uncertain in ponderosa pine forests. Prior to 1880, fires were most frequent on low-elevation islands of ponderosa pine forest formed by plateaus or points (Weibull Median Probability Intervals [WMPI] 3.0-3.9 years for all fires, 6.3-8.6 years for large fires scarring 25(percent) or more of the sampled trees). Fires were less frequent on a higher-elevation mainland site on the South Rim had the longest fire-free intervals prior to European settlement (WMPI 6.5 years all fire, 8.9 years large fires). As in much of western North America, surface fire regimes were interrupted around European settlement, 1879 on the North Rim and 1887 on the South Rim. However, either two or three large surface fires have burned across each of the geographically remote point and plateau sites of teh western North Rim since settlement. To some extent, these sites may be rare representatives of nearly-natural conditions due to the relatively undisrupted fire regimes in a never-harvested forest setting.
Source: International Journal of Wildland Fire
Publisher: CSIRO, http://www.publish.csiro.au/?nid=114