Research: Grassland Fuels and Wildfire Risk

A vast grassland with long, feather-like grasses swaying in the wind under a bright blue sky. In the background, the iconic Flatirons rise against the horizon, providing a striking contrast to the soft movement of the grasses in the foreground. The scene is peaceful and expansive, capturing the beauty of nature.

Boulder County Parks & Open Space offers grants for research on county open space lands each year. All proposals are reviewed by a team of resource specialists, and awarded research projects are monitored during their activities on open space.

The following is a summary of a 2023 study conducted by Jonathan Henn and Katharine Suding at the University of Colorado Boulder. The project focused on understanding grassland fuels and their relationship to wildfire risk mitigation.

Abstract

Grassland fuels are severely understudied, and their variation is often underestimated in fuel models used for fire modeling. However, understanding their variation can be extremely useful for making management decisions about when, where, and whether to attempt fuel reduction treatments. To better understand how grassland fuel characteristics vary across the Front Range landscape, we set up a network of 120 fuel monitoring plots across the primary grassland types in the region. We measured fuel characteristics during midsummer (July) and fall (October) to determine spatial and temporal variation in grassland fuel structures. We found that vegetation type has large consequences on fuel characteristics and that a combination of vegetation type, topography, soils, prairie dog presence, and vegetation cover can predict fuel characteristics moderately well (R2 from 0.44-0.98). We also conducted a fire modeling exercise to investigate how fuel loads, fuel moisture, and wind interact to affect fire behavior. This exercise shows that fire spread is sensitive to fuel moisture and fuel loads in a non-linear way where spread rate can be slower than the wind speed when moisture is higher and fuel loads are lower. Overall, these results have implications for determining areas of higher priority fuel management due to high productivity.

Full Report