After the massive 2017 firestorm that hit northern and southern California, it is important to take a look nature’s relationship to fire and how nature has been characterized in the wake of what has happened. For this discussion, we will be focusing on the fires in Napa and Sonoma Counties, although most of what we write is directly applicable to the Thomas Fire in Ventura and Santa Barbara Counties as well.
How We Talk About Nature. First and foremost, we need to reframe the discussion and consider the words we use. Nature provides beautiful habitats for a wild diversity of creatures. It is not “fuel.” Fuel is what we put into our cars and what heats and cools our homes. A dense thicket of shrubs offers the wild foundation of green for countless organisms from lichens to wrentits. It is not “overgrown.” The term “overgrown” can be used to describe our gardens and backyards perhaps, but it’s not an appropriate or accurate way to describe our wildlands, no matter how many fire or flood cycles have been missed. Saying nature is “overgrown” is at best, derogatory. “Overgrown” is a highly subjective term based on hubris, not the needs of a woodrat, a Scrub Jay, or a ceanothus silk moth.
Words matter. Due to the loaded terms that are continually used to describe the natural environment, it is no wonder that a significant number of politicians and members of the public either fear or distain nature and see no reason why we should protect it. To them, terms like fuel, overgrown, brush, and dead trees, have become bludgeons to attack those of us who want to protect the rapidly vanishing natural environment and as an excuse to log, clear, and eliminate our public lands.
Natural Fire Return Intervals. The best way to determine what the natural fire cycle is for an area is to examine the frequency of lightning-caused fires.
Napa and Sonoma Counties have some of the lowest lightning frequencies, and hence lightning-caused fire, in California. From 1919 to 2016, Sonoma County had a total of 489 fires per million hectares per year. Only 6 were from lightning (the rest have been human- or unknown-caused). In contrast, the half-million hectare northern California County of Siskiyou had 44 lightning-caused fires in the year of 2004 alone. Therefore, before humans arrived in the Napa/Sonoma region, fires of any significance were likely spaced over relatively long periods of time, probably on the order of 50 – 100 years or more. This kind of fire return interval cannot produce the fire suppressed/”overgrown” environment the media has described. We have a response to one of the worst examples of reporting like this on our chaparral blog.
When discussing natural fire return intervals, people often ask about Native American burning.
We know they burned the landscape. Exactly where and how frequently is a subject of much debate and is mostly knowledge lost in time. But it is fair to say that early Native American burning was likely responsible for creating some of the patchiness of plant communities in the Napa/Sonoma region as well as in other areas. It is also reasonable to hypothesize that Native American burning, especially around villages, began the process of eliminating native shrublands in favor of more open landscapes.
As with wine makers who clear their land for vineyards, Native Americans modified the land to obtain what they wanted as well.
Interestingly, the loss of chaparral in California due to type conversion has been discussed in one of the earliest works on chaparral by William Cooper (1922). He did some, as he wrote, “painstaking” searches to locate remnants or relic stands of chaparral in areas presently dominated by non-native grasslands in northern California. He also interviewed a number of old timers who remembered what the place looked like before the onslaught of settlers changed the place forever. He found ancient chamise shrubs along fence rows, on rocky ground, in ravines, etc., where humans and cattle couldn’t finish off what was left (Fig. 1 below). He discusses several relic sites in Colusa County near Arbuckle, in the Santa Clara Valley, and near Hershey in the Sacramento Valley. He also suggests that the impacts by European ranchers/settlers were, “of small importance compared with the effects produced by the aboriginal population” due to yearly burning practices.
The steady transformation of California’s wilderness began about 10,000 years ago after the arrival of America’s first peoples.
The frequently heard call that we should return to what we think Native Americans did on the landscape is counterproductive to our current efforts to protect what natural environments we have left. With millions of people lighting fires, the climate changing, and invasive, non-native weeds that Native Americans never had to deal with, when it comes to land management, it is best to consider the challenges we are facing in the future.
Fig.1. Chaparral relics (chamise) surrounded by non-native grassland in Amador County, CA.
Fire and Habitats Today. So how does this all figure into our land management today? We obviously cannot allow what few natural fires we have to run their course in populated areas. And we certainly can’t let human-caused fires run. Hence, we suppress. In wildland areas far from communities, we can let fire play it’s natural role. Most natural parks do this now. Sometimes, however, the public and their elected leaders do not have much patience for that.