Our letter to journalists.
We respectfully request that in future articles on wildfires in California, you dispense with the word “overgrown” when describing environments dominated by native shrubs as used in your recent articles on the Detwiler Fire (e.g. overgrown shrubs, overgrown vegetation)(1). Or at the very least, question those who claim such things.
The notion that vegetation or shrubs in native shrublands like chaparral (the dominant native plant community that surrounds Mariposa) can be “overgrown” is not logical. By its very definition, “overgrown” is a human-centric term that implies something needs to be trimmed or, in case of shrubs, manicured like a garden would be. This is the last thing we want to communicate if we desire to protect what little wild nature is left in California. Plants grow, some large, some small. There is no natural process in a native shrubland environment that could produce overgrowth. Such a concept is in conflict with the basic principles of evolution.
Trails can be overgrown, as can backyards, and tree plantations. But these are human inventions, not natural systems.
Usually the notion of “overgrown” is in reference to claims that past fire suppression has created unnatural amounts of vegetation. While this is true for some forested systems below 7,000 feet, it is not true for native shrublands (2).
We agree with you that yes, “The flames are being fed by tall grass… that sprouted along the central Sierra Nevada foothills during the winter rains” as you quoted a Cal Fire representative as saying (7/20/2017). Non-native, invasive grasses are incredibly flammable and pose a real threat to communities and natural ecosystems. But it is incorrect to claim that native shrubs have produced much in the way of additional vegetation because of the past rainy season. Native shrubs typically grow quite slowly. At any rate, any new vegetation has a high water content and does not burn easily.
As you know, words are powerful and can communicate and reinforce biases and stereotypes that can lead to unfortunate consequences. When people read that wildfires are “being fed” by “overgrown shrubs,” this encourages the use of destructive land management practices in wild native shrublands such as clearance activities and prescribed burns (3). The chamise/manzanita dominated chaparral found in the Mariposa region represents a rapidly vanishing native ecosystem. We need to do what we can to protect it, not blame it for human-caused disasters. Please see photo below.
We also urge you to question the continual claim by fire officials that “many dead trees” play a significant role in fueling wildfires. In regards to the Detwiler Fire area, the primary trees are scattered oaks and gray pines, neither of which have been severely impacted by bark beetles or the recent drought. While there are certainly groups of dead trees in some locations, the reference to dead trees appears to be a standard comment from some regardless of the environment in which the fire is occurring (see map below). Secondly, there is growing scientific evidence that even in areas where there are a large number of dead trees (mostly conifers), the fire risk is not significantly increased (4).
We know you are doing your best to report on a situation where emotions are high and the possibility of loss of life is quite likely. As climate change continues and populations grow, we will only see more of this. So it is becoming increasingly important for journalists like yourselves to question those who are responding to the consequences of both to ensure they are addressing the real issues.
PHOTO: The chaparral dominated environment near Mariposa (photo taken August, 2015, about 10 miles north of town along Hwy 49. looking north). Note the gray pines to the left of center near the highway. They are typically very sparsely distributed. Also note the lack of any dead specimens. The is a beautiful, native California environment, not one filled with “overgrown” vegetation. Unfortunately, this area has been burned in the fire (see fire perimeter map below).
Citations for additional information:
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Regarding the dead tree issue, the above map of Mariposa County shows the state’s tree mortality map overlaid with the Detwiler Fire perimeter (light area left center). You’ll notice the fire has basically not involved much in the way of dead trees.
The colors yellow to burgundy indicate the assumed level of tree mortality with a rather wide range.
o Deep burgundy depicting areas with more than 40 dead trees per acre
o Red depicting 40 – 15 dead trees per acre
o Orange depicting 15-5 dead trees per acre
o Yellow depicting 5 or less dead trees per acre
Below: the Detwiler Fire perimeter.