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Analysis of tree regeneration following large wildfires

A burned area on the northeast side of Yellowstone Lake. Photo: August 16, 2020 by Bill Gabbert

Below are key findings and a brief summary from a paper titled, “Post-fire tree regeneration and fuels across the Northern Rockies following large wildfires: science meta-analyses, scenarios and manager workshops”.

The principal investigators were:

Penelope Morgan, University of Idaho
Camille Stevens-Rumann, Colorado State University
Jarod Blades, University of Idaho

As more of the western US burns in large wildfires it is critical to managers and scientists to understand how these landscapes recover post-fire. Tree regeneration in high severity burned landscapes determines if and how these landscapes become forested again, while changes in fuels structure influences how these landscapes may burn again. In this study the researchers compiled two large datasets to understand region-wide patterns and drivers of tree regeneration and surface fuel accumulation post-fire. The results demonstrated that natural tree regeneration in the Rocky Mountains is declining with increasingly hotter and drier climatic conditions and that close distance to living trees were critical for tree establishment.

Key Findings:

Fewer tree seedlings established far (>270 ft (90m)) from living tree seed sources
Hot, dry climatic conditions in the years after fires resulted in lower tree regeneration
Climate and distance to a living tree are two of the most important factors in determining tree regeneration responses. Thus, these factors should be considered when making post-fire tree planting decisions to optimize the likelihood of success.
Fuels increase with years since fire, but this is mediated by site productivity and burn severity. Managers should carefully monitor burned landscapes and reduce risk during these peak tree fall periods 9-14 years post fire. Subsequent burning may reduce fuel loads, but vegetation considerations should be considered to mitigate the effects of repeated high intensity disturbances.
The need for ongoing research-management partnerships that synthesize and translate current science, such as the workshops and decision tool we designed, is imperative in the face of increasing agency workloads that constrain agency specialists from adequately addressing climate change in post-fire planting and management decisions. As such, our findings suggest that the workshops were effective for the rapid delivery of science in a setting that capitalized on the use of visualization and interactive participation. Perceptions of the usefulness and credibility of the workshop materials and decision tree was high.

The full document can be seen HERE.