Central Oregon currently lacks the site-specific fire and forest histories that are necessary for scientifically based land-management planning in the region.

For a region with such extensive fire-adapted ecosystems, surprisingly few fire and forest histories have been reconstructed from tree rings, and these only at stand scales and in only a few of the region's forest types. In addition, climate change is recognized by the chief of the Forest Service as one of three critical new resource issues for the 21st century (link: http://www.fs.fed.us/climatechange). Anticipating the effects of climate change on future fire requires that we understand the effects of climate variation on past fires. It also requires that we bridge the past, present, and future by identifying the climate drivers of 20th-century fires from written archival records, and using this information to project future fire regimes. Finally, there is an urgent need to collect tree-ring evidence of past fires because modern prescribed burning and extensive, severe wildfires are rapidly and permanently consuming this evidence.

In cooperation with the Central Oregon Fire Management Service (Deschutes and Ochoco National Forests and the Prineville District of the Bureau of Land Management) and The Nature Conservancy, we began reconstructing fire and forest histories from tree rings in central Oregon in the summer of 2009.

PRINCIPAL INVESTIGATORS

Emily K. Heyerdahl, Research Forester; Donald A. Falk , and Rachel Loehman, Research Ecologist

GOALS AND OBJECTIVES

1. Reconstruct annually accurate multi-century fire and forest histories from tree rings sampled systematically at 7 sites (approximately 1200 ac (500 ha) each). Of these, 5 sites will span a range of forest types but be centered on mixed-conifer forests (2 sites on the east-slope of the Cascades and 3 sites in the Ochocos); 1 site will be dominated by western juniper; and 1 site by lodgepole pine. Approximately 30 variable radius plots are sampled on a grid at each site.
2. Estimate modern fuel loading at each plot. We are using a new method that efficiently provides accurate estimates of loading by size class in the field (Keane, R.E. and L.J. Dickinson. 2007. The Photoload sampling technique: estimating surface fuel loadings from downward-looking photographs of synthetic fuelbeds. Gen. Tech. Rep. RMRS-GTR-190). Fuel data will be used to parameterize fire models.
3. Assess the confidence with which our fire histories could be extrapolated to unsampled areas by inferring the drivers of spatial variation within and among our sampling sites, using a combination of GIS and fire simulation analyses.
4. Identify the climate drivers of past regional-fire years in central Oregon from our tree-ring data, and for modern regional-fire years from written archival records of fire. Use these calibrations to project future fire regimes using regional climate scenarios. For this effort, we will use existing fire chronologies, the data we collect at our six gridded sites, and fire chronologies from 3 to 6 additional sites that historically sustain frequent surface fires (approximately 20 trees collected over approximately 75 acres (30 ha)).
5. Link with landscape fire, vegetation, and climate change simulation model research that will simulate historical and potential future fire and vegetation dynamics in central Oregon. This work will be done by Rachel Loehman using FireBGCv2.

PROJECT STATUS

As of December 2011, we have completed field sampling of over 6500 trees and are currently preparing and crossdating  wood samples and analyzing field data. We anticipate completing data analysis and writing of reports and journal articles in 2013.

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FUNDING ORGANIZATIONS

This project is funded by the Forest Service (Rocky Mountain Research Station and Region 6) and by The Nature Conservancy. This work is conducted in cooperation with the Central Oregon Fire Management Service, a consortium of the Deschutes and Ochoco National Forests and the Prineville District Bureau of Land Management.