U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 145, November 2011


US government work.


New knowledge of fire regimes in the pinyon-juniper woodlands of the interior western United States has altered management views. Once known as being at low wildfire risk, these woodlands are now at a higher risk for severe wildfires because of high tree densities exacerbated by ongoing drought and region-wide bark beetle (Ips confusus) infestation. To help reduce fuels and fi re hazards and to create defensible space in the wildland urban interface, regional land managers have conducted thinning-piling-burning treatments. Recently, however, a different treatment has been used—mechanical mastication. Although mechanical mastication is typically more cost effective, there is concern about how these treatments may be affecting the existing soils, microbial populations, and vegetation, as well as the potential for non-native species invasion. To better understand these effects, the Dolores Public Lands Office-Service Center of the San Juan National Forest contacted the Rocky Mountain Research Station to conduct a study on three sites in southwestern Colorado. Researchers randomly assigned treatment methods—mastication, thinning-pilingburning, or untreated—within each site and took measurements before and after treatments to assess the treatment effects. Researchers then used the study results to confi rm and communicate the consequences and benefi ts of these treatments.