Fire, Logging and Giant Sequoias

Once again The Sacramento Bee has attacked the John Muir Project, this time inaccurately claiming that we oppose prescribed fires, in the course of discussing the current Washburn Fire, which is miles from the area subject to the current lawsuit against illegal logging in Yosemite. The fire is partially burning in the famed Mariposa giant sequoia grove in Yosemite National Park. Though The Bee’s editorial was later changed, the inaccurate statement, which circulated for most of a day before it was modified, nevertheless needs to be addressed.

The John Muir Project supports prescribed fire in some circumstances, and not in others, which is true of just about everyone in my scientific field of forest and fire ecology. For example, we support prescribed fire as an additional buffer around communities, after fire-safe measures like home hardening and defensible space pruning have occurred. I make this point in nearly every presentation I give, and have done so for years. We do not support prescribed fires being set on hot, dry, windy days by agencies, as we saw recently in New Mexico, when multiple towns were burned down. And, we do not support agencies like the Forest Service or Park Service doing commercial logging projects and dishonestly calling it a “prescribed fire” project when they burn the logging slash debris in a field of stumps.

Like most forest and fire ecologists, the John Muir Project believes that managed wildfire (letting lightning strikes burn without suppression) should be the priority, in forest wildland areas that are not close to communities. Only natural, mixed-intensity fires create habitats for the full range of native wildlife species.

When it comes to giant sequoia groves, this is another place where prescribed fire can be beneficial or harmful, depending on the circumstances. Previous fire, whether from a controlled burn or a lightning strike, will influence future wildfire behavior for a very short period of time, and much less so when it’s high fire weather. There is more to it than that, however.

A primary threat to giant sequoias is the “massive failure of sequoia reproduction” due to an almost total lack of natural, mixed-intensity wildfires over the past century, until of course the past seven years. Giant sequoias need fire to effectively reproduce, and they have been slowly dying off for more than 100 years due to fire suppression, without new sequoia seedlings growing. Now, however, sequoia seedlings are abundant in the recent burns, as my colleagues and I have observed firsthand in many groves.

But it’s not just any sort of fire that sequoias need. Low-intensity surface fire, resulting for example from controlled burns, causes a severe lack of sequoia reproduction that is often not significantly different from no fire at all. In fact,sequoias regenerate best, by far, in moderate- and higher-intensity fire patches — the very sort of fire that rarely results from controlled burns. These higher-intensity fire patches do three things that sequoias need: generate enough heat to allow seeds to be released from sequoia cones; consume the thick duff and litter on the forest floor and create a nutrient-rich bed of mineral ash for seedlings to grow; and create more sunlight to stimulate seedling growth. A small percentage of mature sequoias will be killed by such fires, of course, but not nearly as many as initially estimated by federal agencies recently, based on very limited and preliminary data. Importantly, many, many more sequoias will grow due to these mixed-intensity wildland fires. This is intrinsic in their cycle of life.

Misinformation and fear isn’t helping this issue. Let’s focus on the science, and what nature has to teach us, as the Park Service is supposed to do, and let that guide us. And, let’s focus our attention and resources on creating fire-safe communities through home hardening and defensible space, rather than more taxpayer-subsidized logging that is totally ineffective in curbing wildfires that are driven mainly by weather and climate.

Chad Hanson is a research ecologist with the John Muir Project. He is a co-editor and co-author of “The Ecological Importance of Mixed-Severity Fires: Nature’s Phoenix” and the author of “Smokescreen.”