The Effects of Fire Intensity on Trees and Productivity

This FireEarth Science Brief synthesizes research evaluating how varying fire intensities affect tree physiology, mortality, and post-fire productivity in Pacific Northwest forests. Researchers at the University of Idaho conducted laboratory and prescribed burn experiments using different Fire Radiative Energy Density (FRED) doses to assess impacts on lodgepole pine, western larch, and ponderosa pine.

Laboratory experiments demonstrated clear dose-response relationships in seedlings: increasing FRED doses reduced net photosynthesis, increased crown scorch, and elevated mortality rates. All seedlings exposed to the highest dose (1.2 MJ m⁻²) died within four weeks. In mature ponderosa pine, overall FRED dose did not predict growth response, but peak fire radiative power per unit area was strongly associated with reduced radial growth.

Findings improve mechanistic understanding of fire severity beyond remote sensing metrics and provide guidance for prescribed fire planning, species removal strategies, and post-wildfire rehabilitation.

The production of this science brief was supported by the National Science Foundation through award DMS-1520873.