How valuable are forests of the American West that have experienced wildfire? With over 10 million acres that burned across the region in 2015, that question has sharply gained in prominence. Many of us understand that an average of 30 million acres burned annually in wildfires of the 1920s and 1930s – and acreages were even higher during prior decades (according to U.S. Forest Service records).
Even so, the sheer power of today’s visuals often pose a challenge in accepting that wildfires – with all their natural variables including low, medium and high severity – have been an integral part of western ecosystems for eons.
The curious conservation biologist who hikes through post-fire forests will inevitably be rewarded with a number of sights that attest to their high ecological value. A more focused way to understand the forests is to venture out in search of rare birds. In 2014 and 2015, teams of biologists worked on protocol surveys to quantify the nest density of black-backed woodpeckers, which are increasingly rare in the Sierra Nevada-Cascades Region. With their glossy black backs, the woodpeckers are ideally equipped to live in burned forests abundant with high densities of snags (standing dead trees), each of which quickly grows rich with wood-boring beetle larvae – the woodpeckers’ preferred food source. Also colonized by bark beetle larvae, the “snag forests” support Lewis’s, pileated, hairy and white-headed woodpeckers, sapsuckers, northern flickers, nuthatches, an astonishing bustle of wildflowers, buzzing insects, song birds and other wildlife including deer, bears, and even Pacific fishers. Mornings are little short of dazzling.
The teams of biologists who began their surveys in 2014 were led by Dr. Chad Hanson (Director, John Muir Project of Earth Island Institute) and senior biologist Tonja Chi. For a thorough study, both burned and unburned forest plots were randomly selected across national forests of the Sierra Nevadas. Surveys were conducted in triplicate, within 300-hectare plots. Each plot contained three 100-hectare subplots, making it convenient for three biologists to survey one subplot at a time.
Preliminary results indicate that nesting black-backed woodpeckers are found almost exclusively in recently burned forests. The woodpeckers are also found in unburned, “beetle kill” forests (with snags that are abundant with beetle larvae). In both forests, the common denominator for black-backed woodpeckers is high densities of snags. True to their reputation as keystone species, the woodpeckers provide nests for a host of other birds including mountain bluebirds, western bluebirds, wrens, nuthatches, mountain chickadees and even for squirrels. During the 2015 surveys, team members also documented other rare birds in the post-fire forests, including the northern goshawk, California spotted owls, and Williamson's sapsucker – all in post-fire forests.
These forests typically include areas that have burned with high severity (where most trees turn into snags), moderate severity (anywhere between one quarter and three quarters of the trees had turned into snags) and low severity (where it’s mostly the understory that has burned). While fires may scorch large patches, many trees charred by the flames remain alive at the crown. They flush with new growth soon after the burn. However, post-fire forests are still misunderstood and routinely logged, so they are highly threatened habitats.
According to many experts, fire and black-backed woodpeckers are inextricably linked. The long-term black-backed woodpecker study will continue through the 2016 field season and is anticipated to corroborate results of existing data from other sources, and to provide valuable data about the woodpecker’s habitat uses. Solid estimates of the Sierra Nevada-Cascades population of black-backed woodpeckers are also expected to result from the study.
Many other observations are revealing the high value of post-fire forests. A year after the King Fire in El Dorado National Forest, carpets of conifer seedlings were observed rising from the ashes along with three rare plants. One of them, the longfruit jewelflower (first described by Glen Clifton and Roy Buck in 2007), had never been sighted in El Dorado before. Two years after the 2013 Rim Fire in Yosemite National Park and the Stanislaus National Forest, vast areas with mature pines that were presumed dead had bounced back to life. Seedlings were popping up everywhere in the high-intensity burn areas.
Authors Jon Keeley and others demystify the abundance of regenerating plants by explaining the “fire-generated chemical stimulus for germination” found in many plant families.” An exciting new book, The Ecological Importance of Mixed-Severity Fires: Nature’s Phoenix (edited by Dominick DellaSalla and Chad Hanson), gives us dozens of examples of the high biodiversity found in post-fire forests, and an ever-increasing number of studies are speaking reams about the value of forests after wildfire.