5th Symposium on Fire and Forest Meteorology and the 2nd International Wildland Fire Ecology and Fire Management Congress

Wednesday, 19 November 2003: 4:00 PM
A comparison of fire regime characteristics reconstructed from fire scar data and mapped fires in a frequently burned Arizona wilderness
Calvin A. Farris, University of Arizona, Tucson, AZ; and C. H. Baisan and T. W. Swetnam
Accurate information about historical fire regimes is needed to inform fire and restoration management planning and to understand the long-term effects of fire and climate on vegetation dynamics. Fire scars are the primary source of physical evidence for reconstructing fire regimes in forest historically dominated by frequent, low intensity surface fires. Unfortunately, fire scar evidence is often incomplete or fragmented in many landscapes so assumptions about fire spread and data analysis are required. An improved understanding of how well point-based fire scar data represent spatial and temporal characteristics of a continuous process like fire is needed to improve our understanding of past fire dynamics. Ponderosa pine forests in the Saguaro-Rincon Wilderness in southern Arizona have experienced an unusually high frequency of well-mapped 20th century fires, with some stands having burned at least nine times since the 1940ís. This landscape provides a unique opportunity calibrate fire scar data against recurrent fires with known dates and extents. In this study we compare spatial, temporal, and seasonal fire regime parameters derived from point-based fire scar data and area-based mapped fire perimeters. We established a comprehensive fire scar sampling network utilizing systematic, random, and targeted sampling. In general, the dates and spatial patterns of fire frequency reconstructed from fire scars corresponded well with mapped fires but are scale dependent. Synchronous fire scar dates most often represented continuous burns rather than small, isolated events. We will present the preliminary results of our comparisons and discuss key implications with respect to the interpretation of fire history data and fire management planning

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