Thomas W. Swetnam

Contact Info


Laboratory of Tree-Ring Research
University of Arizona
105 West Stadium
Tucson , AZ 85721, United States

Publications in Fire Ecology

Spatially and Temporally Variable Fire Regime on Rincon Peak, Arizona, USA
Pages: 3-21
DOI: 10.4996/fireecology.0501003

Spatial and temporal patterns of fire history are affected by factors such as topography, vegetation, and climate. It is unclear, however, how these factors influenced fire history patterns in small isolated forests, such as that found on Rincon Peak, a “sky island” mountain range in southern Arizona, USA. We reconstructed the fire history of Rincon Peak to evaluate the influences of broad-scale (i.e., climate) versus local-scale (i.e., topographic) factors on fire occurrence and extent.  [Read More]

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Special Issue: Fire History in California
Pages: 1-3
DOI: 10.4996/fireecology.0503001

A common refrain that fire historians hear from managers and scientists is: “Haven’t we done enough fire history studies already, especially in ponderosa pine? What more is there to learn?” It is true that there are dozens of published studies in western North America using tree rings to evaluate the historical range and variability of past fire regimes. It is also true that the majority of these studies were conducted in pine dominant or mixed-conifer forests where moderate to high frequency surface fire regimes prevailed for centuries before the fire suppression era. Despite the substantial body of existing fire history literature, this special issue of Fire Ecology serves to demonstrate that, in fact, there is still much more to learn.  [Read More]

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Using Bigcone Douglas-Fir Fire Scars and Tree Rings to Reconstruct Interior Chaparral Fire History
Pages: 35-56
DOI: 10.4996/fireecology.0503035

Bigcone Douglas-fir (Pseudotsuga macrocarpa [Vasey] Mayr) is a long-lived, fire-adapted conifer that is endemic to the Transverse Ranges of southern California. At the lower and middle reaches of its elevational distribution, isolated stands of bigcone Douglas-fir are surrounded by extensive stands of chaparral. Our dendrochronology investigations have revealed that these ancient trees commonly record multiple past fires as fire scars in their lower boles. We hypothesized that the fire-scar record found within and among bigcone Douglas-fir stands reflects the temporal and spatial patterns of fire in the surrounding chaparral.  [Read More]

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Multi-Millennial Fire History of the Giant Forest, Sequoia National Park, California, USA
Pages: 120-127
DOI: 10.4996/fireecology.0503120

Giant sequoias (Sequoiadendron giganteum [Lindl.] J. Buchholz) preserve a detailed history of fire within their annual rings. We developed a 3000 year chronology of fire events in one of the largest extant groves of ancient giant sequoias, the Giant Forest, by sampling and tree-ring dating fire scars and other fire-related indicators from 52 trees distributed over an area of about 350 ha. When all fire events were included in composite chronologies, the mean fire intervals (years between fires of any size) declined as a function of increasing spatial extent from tree, to group, to multiple groups, to grove scales: 15.5 yr (0.1 ha), 7.4 yr (1 ha.), 3.0 yr (70 ha), and 2.2 yr (350 ha), respectively. We interpreted widespread fires (i.e., fire events recorded on ≥2 trees, or ≥25 % of all trees recording fires within composites) to have occurred in areas of 70 ha to 350 ha at mean intervals ranging from about 6 yr to 35 yr.  [Read More]

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Historical Stand-Replacing Fire in Upper Montane Forests of the Madrean Sky Islands and Mogollon Plateau, Southwestern USA
Pages: 88-107
DOI: 10.4996/fireecology.0703088

The recent occurrence of large fires with a substantial stand-replacing component in the southwestern United States (e.g., Cerro Grande, 2000; Rodeo-Chedeski, 2002; Aspen, 2003; Horseshoe 2, Las Conchas, and Wallow, 2011) has raised questions about the historical role of stand-replacing fire in the region. We reconstructed fire dates and stand-replacing fire patch sizes using four lines of tree-ring evidence at four upper montane forest sites (>2600 m) in the Madrean Sky Islands and Mogollon Plateau of Arizona and New Mexico, USA.  [Read More]

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