USA — Two recently published scientific studies add to a growing body of research on the ecological importance of forest fires, even severe ones, to the integrity of fire-dependent forests in the western U.S, particularly Californias Sierra region.
One study, published in the Natural Areas Journal, documented the ecological importance of forest fires in regenerating unique habitat for numerous plants and wildlife in the Sierra, including rare and threatened ones. The other published in Ecosphere compared historical records of forest fires to todays fires and concluded that todays fires in the Sierra are burning in size and intensity similar to the way fires once burned.
According to Dominick DellaSala, Chief Scientist of the Ashland-Oregon based Geos Institute and lead author of Complex early seral forests of the Sierra Nevada: What are they and how can they be managed for ecological integrity?, Post-fire landscapes are often falsely portrayed as moonscapes, but they actually have some of the highest levels of plant and wildlife diversity of any Sierra forest type with levels comparable to what we see in the regions more appreciated old-growth forests.
A key finding of DellaSalas research showed that post-fire landscapes are rich in large dead trees (snags) that connect a regenerating forest to the eventual old-growth forest that develops over time via the process of forest succession. Imperiled wildlife that depend on snags as biological legacies include the Black-backed Woodpecker, a fire dependent indicator species under consideration for listing as threatened due to dramatic losses of its post-fire habitat from logging, and the California Spotted Owl that forages in post-fire landscapes also damaged by post-fire logging.
DellaSalas findings are relevant to controversial post-fire logging projects that inevitably follow most forest fires, he added post-fire logging and related tree planting removes the very components that forests need to regenerate themselves and this is not restorative as claimed. DellaSala was also lead author on a letter signed by over 200 scientists last January that urged the Forest Service to refrain from massive post-fire logging in the aftermath of the 2013 Rim fire on the Stanislaus National Forest.
Another study, Historical forest structure and fire in Sierran mixed-conifer forests reconstructed from General Land Office Survey data found that severe fires have long been a natural feature of Sierra Nevada mixed-conifer forests. According to William Baker, Emeritus Professor of Ecology at the University of Wyoming, Contrary to what some believe, fires in Sierran mixed-conifers once did, and still do, burn in a pattern of mixed severities that include large patches, up to several thousand acres, of fire-killed trees as part of the natural fire cycle in this region.
Baker tested prevailing assumptions about uncharacteristic fires by examining the US governments General Land Office surveys from 1865 to 1885 and in these surveys examined the recorded forest composition by early surveyors as it related to historical fire influences.
Baker found that there is actually currently less high-severity fire in Sierra forests now than there was prior to the historical surveys, and noted that the current deficit of high-severity fire can be detrimental to forest ecosystems. Logging proposals to reduce fuels and fire severity would actually reduce, not restore, historical forest heterogeneity important to wildlife and resiliency.
Both studies reflect a growing scientific awareness of the ecological role of forest fires throughout the West, particularly severe ones. For example, a team of eleven fire scientists in February 2014 that included both DellaSala and Baker used a variety of research methods and found similar historical evidence of high-severity fires throughout fire-dependent forests in the western US and Canada. Their findings were published in PLoS One and run counter to the widely held assumptions that most forest fires today are burning uncharacteristically severe.
All three studies made similar recommendations for communities living adjacent to fire-dependent forests. Specifically, increased prioritization of fuel treatments are needed nearest homes given escalating costs of fighting fires in the backcountry where suppression forces are particularly ineffective during drought years.