Synthesis of the new North American tree-ring fire-scar network: using past and present fire-climate relationships to improve projections of future wildfire

Increasing wildfire activity in much of North America is having severe impacts on society and ecosystems. Climate change is a key driver of changing fire regimes across North America, with varying expressions across the continent. Modern fire records, while useful, are too short to fully characterize the complex patterns and non-linear dynamics of fire-climate relationships that are required to understand future fire activity in a warmer climate. Tree-ring fire scars offer a unique perspective because they are spatially precise, direct evidence of fires with annual to sub-annual resolution spanning centuries. For the first time, we have compiled tree-ring fire scar records across North America (n = 2,593 sites, 35,602 trees, >300,000 fire scars). Our international team of fire and climate scientists will synthesize the fire scar network and combine it with modern fire records to create a multi-century record of fire across North America. Also, we will use recent advances in paleoclimate methods and the continental-scale network of tree-ring chronologies to reconstruct seasonal climate variables tailored to better understand variability in climate drivers of fire. We will use these new data to address the central question: how will climate drive future fire potential in North America? Synthesis of the new North American fire scar network will enable us to use historical and modern fire-climate relationships to better project future fire regimes in a changing climate across North American forests. We will focus on: 1) multi-century spatio-temporal dynamics of fire-climate relationships across North America, 2) climate drivers of changing synchrony of wildfire (e.g., widespread fire years), 3) cyclical properties of fire occurrence that can provide predictive capacity, including relationships with ocean-atmosphere oscillations (e.g., El Nino/Southern Oscillation and Arctic Oscillation), and 4) combining historical and modern fire-climate relationships to project future wildfire potential at regional to continental scales.



Principal Investigator(s):

Ellis Margolis (USGS - Fort Collins Science Center)

Chris Guiterman (University of Arizona)

Rachel Loehman (USGS - Alaska Science Center)

Sean Parks (US Forest Service)