Lithograph Canyon Prescribed fire, Jewel Cave National Monument in South Dakota. Photo by Bill Gabbert

I thought this issue was settled 20 to 30 years ago, but researchers have recently discovered (again) that prescribed fire can be beneficial to the environment. Some folks at UC Berkeley synthesized 20 years of research throughout the country on the ecological impact of reducing forest wildfire risk through controlled burns and tree thinning. They came to the conclusion that prescribed fire is a good thing.

Some of the researchers’ ecological findings include:

• For the first five years after treatment, some birds and small mammals that prefer shady, dense habitat moved out of treated areas, while others that prefer more open environments thrived. The study authors said these changes were minor and acceptable.
• When mechanical tree thinning was followed by prescribed fire, there was an increase in the overall diversity of vegetation. However, this also included non-native plant species. The researchers recommend continued monitoring of this effect.
• Only 2 percent or less of the forest floor saw an increase in mineral soil exposure, which could lead to small-scale erosion. Other soil variables, such as the level of compaction, soil nitrogen and pH levels, were temporary, returning to pre-treatment levels after a year or two.
• Increases in bark beetles, a pest that preys on fire-damaged trees, was short-lived and concentrated in the smaller diameter trees. Researchers noted that thinning out a too-dense forest stand improves tree vigor and ultimately increases its resilience to pests, in addition to fire.