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Project ID:

11-3-1-27

Year:

2011

Date Started:

08/01/2011

Date Completed:

11/29/2013

Title:

Reconstruction of Fire History Using Tree-Ring and Alluvial Sediment Records in the Western San Juan Mountains, Colorado

Project Proposal Abstract:

There has been an increase in severe forest fires across the western US in recent decades, which is associated with multi-year droughts and warming temperatures. In the southwestern US, high-severity fires in ponderosa pine and mixed conifer ecosystems are considered unprecedented by many fire ecologists. This dissertation research of the Co-PI combines alluvial stratigraphy and dendrochronology at the scale of four tributary drainage basins, in order to reconstruct the fire history of ponderosa pine and mixed-conifer forests in the western San Juan Mountains of Colorado. Alluvial sediment deposits will be sampled from multiple exposures in the valley bottoms of tributary basins and their alluvial fans. When sediment deposits contain charcoal, they are used to interpret past fire events in the contributing basin. The sediment characteristics are used to infer the severity of past fire events, and radiocarbon dating yields a chronology of all sedimentation events. Fire-related sedimentation events have been collected and dated for three of four basins, and a fourth basin is needed, in order to create a regional fire history record. Tree-ring data has already been collected from the four tributary basins, and will help define fire severity interpretations associated with the most recent alluvial deposits (< 500 years). Tree-ring methods reconstruct fire events with annual to decadal precision, by dating fire-scarred trees and tree regeneration ages. Furthermore, a charcoal analysis will be applied to the charcoal samples, which will enhance the interpretations of fire severity based on sediment deposits. The results from the two proxy methods will be combined at the scale of four tributary basins, yielding a fire history record covering the past 4,000 years before present. The GRIN award would support the final data collection, data analysis and the publication of three papers as part of the dissertation project of the Co-PI.

Principal Investigator:

Thomas W. Swetnam

Agency/Organization:

University of Arizona-Tucson

Branch or Dept:

Laboratory of Tree-Ring Research

Other Project Collaborators

Type	Name	Agency/Organization	Branch or Dept
Agreements Contact	Lee Anne T. Peters	University of Arizona-Tucson	Office of Research & Contract Analysis
Budget Contact	Sangita Judge PhD, MBA	University of Arizona-Tucson	Sponsored Projects Services
Co-Principal Investigator	Erica R. Bigio	University of Arizona-Tucson	Laboratory of Tree-Ring Research