Megafires Today: Couldn’t we just rake?

I received this email in my inbox about wildfires and management…

Hi Dr. Stavros,

I read the transcript of your talk on wildfires. I am curious: does a lack of tree pruning and underbrush clearing (controlled burning) contribute to the likeliness of wildfires? I know that wildfires happen almost everywhere that there is forest, but it seems like it happens less in forested areas where trees are pruned and underbrush is cleared regularly (i.e., Finland).

My response…

Because of media and uninformed comments by politicians around “raking forests” to prevent catastrophic fires, I have taken the time to respond to this question and am sharing it with you here.
Dear XXX,

What you are asking has a nuanced response, and unfortunately the media and some politicians have tried to over-simplify things.

I’ll start by saying that forest management includes *thinning* (not pruning, which is done in gardens on individual trees), burning brush piles, and prescribed burning. So you are right on that front.

The fuel build-up that we see today, however, is not because we don’t manage our forests, it’s because:

  • we have more land than could ever be managed with machines
  • we limit prescribed burning. There are multiple reasons for this but one of them is public perception that fire is bad, others are related to policies that have conflicting implementations. I say this because the policies may not actually conflict, but the way we implement them precludes us from doing more prescribed burning. Specifically, air quality standards count prescribed burning against jurisdictional contributions to emissions and burn/no burn days don’t account for the full emissions inventory (which is different in winter vs. summer because of different chemical reactions) that could be produced.
  • we suppress most fires out of fear of what they could do. The reality is that the fear is a self-fulfilling prophecy. By suppressing fires, the destruction is much worse. Suppression of all fires is not an option. Here’s why:
    • 2018 California Camp Fire that killed 85 people grew ~80 football fields/min; one football field is ~100 m long. It takes ~15 min for us to identify a fire, and ~45 min to access it in rural areas with limited access and steep terrain. The best fire fighting resources in the world operate over ~1 km/hr, so that’s about 10 football field lengths (not perimeters) in one hour.
    • In 2020 ~4% of California burned. Despite the lives lost and burn infrastructure (e.g., homes), one could argue that that means we are 4% closer to bringing fire back on the landscape. Now, that means we would need to bring back fire every year like we did in 2020. However, not all land needs to burn, and I don’t have the exact % of California that needs to burn vs. not burn, so let’s just say 84% (to make the math easy) of California is wildlands that need to burn. That means, we would need to have 21 years just like 2020 to clear the fuels we do have, AND – here’s the kicker – as soon as we have burned that, some of those lands would have already needed to burn again because of their ecosystem and associated fire regime (which brings me to my final point).

Fire regimes describe how often, how hot, and how big fire needs to occur to keep that ecosystem healthy. A good way to think about this, is that all ecosystems fall on the fire regime spectrum as “fuel limited” or “flammability limited”. “Fuel limited” are ecosystems like Nevada where it’s really hot and dry, but there is limited fuel (unless we have rain the year before). “Flammability limited” systems are places like the Pacific Northwest or **Finland** where they have plenty of fuel, but they don’t really have the right conditions (hot and dry) to sustain combustion and carry fire. How you manage these systems is extremely different. What’s more, is that under climate change, “flammability limited” systems are becoming more hot and dry, and so they are burning (see fires in Arctic this year). If fire occurs too frequently, then we burn through the seed banks of the ecosystem that was there before, and we see something called a type conversion – where a new ecosystem comes in.

Hope this was helpful.

Stay curious,

Natasha Stavros