Light my fire?

“You know that it would be untrue
You know that I would be a liar
If I was to say to you
Girl, we couldn’t get much higher
Come on baby, light my fire
Come on baby, light my fire
Try to set the night on fire.”
– The Doors (1967)

The following was posted by the California Chaparral Institute ( and I thought it was worth sharing their post:

“Next time you hear someone claim California, the Sierra Nevada (pick your spot) is supposed to burn every 5-10 years or so, or when someone uses the pine forests in the Southeast or Arizona/New Mexico as a model of what is supposed to happen in California fire wise, show them this map. The natural fire return interval in California is pretty low… from nothing to pretty darn infrequent when compared to the rest of the country.”

39 thoughts on “Light my fire?”

  1. “Natural” fires are mostly a non-starter, in today’s world of human-caused wildfires. Most of America does not see the major differences, between the two kinds of fires. Similarly, today’s wildfires are burning through much different landscapes, too. The idea that “natural fires” are great for forests just isn’t statistically-important, in the real world of today.

  2. Is there a correlation between frequency of lighting strikes and forest fires? It sure seems counter intuitive since no where in the west, where most forest fires seem to occur have high lightning strike density.

  3. Interesting! But somehow I don’t think frequency directly links to fires on the ground. Many Midwest lightning strikes are during rain storms. Can anyone parse this out further?

      • I don’t think you do. Trying to make a direct correlation between lighting density per square mile and fire return interval shows a complete lack of understanding of fire ecology. Thanks.

        • Thanks Jim. I don’t think your reading comprehension is very strong. As I clearly stated “The following was posted by the California Chaparral Institute.”

          • Matthew I will state again, I don’t think you understand the basics of fire ecology. Is there a reason you decided to share this nonsense commentary? I find the dis-information campaign you and others wage against the basics of fire ecology to be offensive. You and others push nonsense information to try and confuse the general public in order to push a political agenda that is founded on emotion rather than grounded science.

            When commenting, please consider the three doors that charitable speech must pass through. The gatekeeper at the door asks, “Is it true?” (NOPE) The second gatekeeper asks, “Is it helpful?” (NOPE).


            • Thanks again for the lecture Jim. I do understand basic fire ecology and could care less if you don’t think so. You also seem to have a rather selective ‘nonsense’ detector. You may wish to seek treatment for that.

              Please address your concerns with what the California Chaparral Institute wrote with the California Chaparral Institute:

              The Chaparral Institute
              PO Box 545
              Escondido, CA 92033
              Phone: 760-419-5760

              P.S. However, I would love to see some documentation from you of the supposed “dis-information campaign” that you claim I “wage against the basics of fire ecology.” Personally, I find your allegation “to be offensive.”

              • Well you decided to post this for some reason. I stated my hypothesis of why I think you did. Please help me understand: Do you think that a map of year round lightening density (regardless of time of year) is a surrogate for fire return interval? Does central VT or NH have a more frequent fire return interval than southern California because it receives a higher density of year round lightning?

                • No, I personally don’t think that a map of year round lightening density (regardless of time of year) is a surrogate (or has an absolute direct correlation) for fire return interval.

                  I personally do think that many people over the past 20 years or so have spread “nonsense” basically claiming or inferring that all wildfires used to burn frequently every few years and burn at a low intensity. That’s really only true of certain ecosystems and certainly not true at all of vast areas of the country, including many mid- to high-elevation forested ecosystems and also not true in many other ecosystems, such as chaparral.

                  Basically, I thought it was an interesting map of lightening strikes and as I wrote after the Door’s lyrics, “The following was posted by the California Chaparral Institute ( and I thought it was worth sharing their post.

                  Finally, I would very much appreciate you showing some documentation of the supposed “dis-information campaign” that you claim I “wage against the basics of fire ecology.” If this is all you got, that’s some incredibly weak sauce Jim. I’m totally fine with you under-estimating me, or not liking me, but please stop making stuff up about me. Thanks so much.

  4. The map showing lightning strikes from 2008-2017:

    1) Doesn’t tell us anything about the historical or future “natural fire return interval in California”. Climate and forest cover changes all of the time.

    2) Doesn’t support a “hands off – let it burn” policy when ignitions by humans runs 85% nationally & 90% in Ca. As posted previously on this site (trusting to memory on the Ca. number). With acreage burned by humans around 50% of the total.

    Therefore: As population increases, the WUI expands as does visitation to forests. Therefore, the need to control stand density by thinning and controled burns increases in those areas where the probability of human access increases. Such areas include the areas around and in the WUI as well as public access road sides (regardless of traffic level) adjacent to forests.

  5. Jennifer Balch has published on this topic (human-caused fire) several times and gave a NAS presentation on it a couple of years ago. There are many places on that map where lightning is rare, yet burning was common in the past – why? People managing natural resources – for basketry materials, for food, and for other purposes. We will probably never fully understand the process that they used to decide when and where to burn.
    People are still a major source of fire starts – but we’re not starting them for the same reasons. In the State of Washington, the number of human-caused fires dwarfs the number of lightning-caused fires.
    The Carr Fire in California (that threatened Redding, CA a few years ago) was started by a wheel coming off of an RV and sparking a fire. There was a major fire in southern Oregon a few years ago that spread onto the Umpqua National Forest and burned thousands of acres due to a spark from a mower being operated on private land (and in violation of fire restrictions).
    It is impossible to stop human-caused fires – does that mean that we do nothing about them and the risks they present to people?

    • As I wrote earlier, the map shows lightning frequency and its relation to natural fire return intervals. It has nothing to do with other causes. Therefore, it provides an interesting proxy for fire patterns prior to when wheels were coming off RVs.

  6. I worked on the Groveland RD of the Stanislaus National Forest, and saw a map overlaid with “Fires per century” (the last century). The map was made using tree ring studies. Parts of the Ranger District had up to 14 fires in the last 100 years. They do, by the way, get lots of lightning, during the hot and dry summers.

  7. First of all, if there is a common theme on this blog it is ridicule and ad hominem attacks leveled against people the attackers have never met. So this guy Jim, who I have never seen post here before, arrives and calls Matthew a liar and someone who is engaging in a misinformation campaign? How is this OK? Why is Jim still able to post here?

    Since it apparently OK to get personal here… Jim, would you like to give Matthew a phone call so you can call him a liar in person? I just got off the phone with him myself. Please let us know.

    Secondly, this litany here of logical fallacies that avoid the actual topic being discussed continues to amaze me.

    Let’s looks at the data, shall we?

    1. The map shows lighting frequency.

    2. The most frequent pyrogenic ecosystems, the southwestern ponderosa pine forests and the southeastern longleaf pine forests, correlate perfectly with the lightning frequency shown in the map.

    3. Again, looking at the map, one of the lowest lightning frequencies in the US is found along the coastal plains and coastal ranges of California. That corresponds perfectly with the long fire return intervals found there. (e.g. Mt. Tam in Marin County – fog, high humidity, and next to zero lightning, a high fire frequency regime does not make).

    4. Where you find higher natural fire frequencies is (as shown on the map), is guess where? In the Sierra Nevada.

    Larry, good grief. The map is not showing anything other than lightning frequencies. Of course there are other variables involved. And Gil, how did anything in this map suggest anything about “hands off” management?

    So yes, lightning frequency is an excellent indicator of natural fire return intervals. If not, can anyone please offer up a place on this map where an ecosystem with a high frequency, low severity fire regime exists where there is a 0-.75 flash density. Please?

    I’m not sure why such information is so offensive. Perhaps a bias concerning the source, sensitivity about a particular paradigm being challenged?

    • I’m sorry that is not correct. Year round lightening density does not directly correlate with mean fire return interval. Many of the areas with high lightening density receive that lightening with significant precipitation outside of the fire season. I don’t know how to post images here but if I could you would see that a map of area burned from lightening fires shows the exact opposite pattern as lightening density for the majority of CONUS.

      • Jim

        I am with you. Would you kindly post a link to your “map of area burned from lightening fires shows the exact opposite pattern as lightening density for the majority of CONUS.”

        • I think I figured out how to get the map online, see here:

          Map is area burned (acres) from all fires that were defined as lightning starts from 1992-2017 from the USFS fire occurrence database. The shapefile of ignition points (not fire perimeter) were selected to only show lightening fires and converted to raster with ‘sum’ function.

    • Since I haven’t taken Fire Ecology 101 I look at this map and your thesis that lightning frequency correlates with natural fire frequencies and have a few questions. Do the Cascades, the Idaho Panhandle and Southern California have comparable fire frequencies? All have a 0-0.75 flash density. Is the fire frequency highest in Florida, Louisiana, and Oklahoma? Is there a flash density threshold required for frequent fires? You mention the Sierras a as having a greater fire frequency than the coast yet their flash density is only slightly higher 0.75 to 1.5 which is still an order of magnitude lower than many places on the map?

      • Fire regimes even within various mountain ranges or geographic regions can vary greatly based on a variety of factors including elevation, slope and aspect. For example, the “Idaho Panhandle” would have everything from high-frequency, low-severity fires on south and south-west facing slopes at lower elevations to areas of low-frequency, high-severity fires in upper elevations and north-facing slopes. The Idaho Panhandle is also home to some very wet riparian areas and canyon river corridors that contain western Red Cedar (well, the ones that we’re already cut down anyway), Pacific Yew and Hemlock and those ecosystems have an entirely different fire ecology than other low elevation places in the same region.

  8. Just for the record, I have seen (and counted) 22 lightning strikes in just one minute, while on duty at my fire lookout. The map doesn’t seem very accurate, to me. The key takeaway is that with so many human-caused wildfires that cannot be prevented, we should manage those forests with those facts in mind. Thinned forests survive human-caused fires (which burn more intensely than ‘natural’ fires) better than unmanaged forests do.

    Again, we don’t care so much about ‘natural’ ignitions as much as human-caused fires.

    • Again, Larry, this map has nothing to do with thinned forests, human-caused fires, how to prevent fires, or your fire lookout. It has to do with the natural fire return interval which dictates the evolutionary patterns of ecosystems.

      Just for a moment, step away from your forest management focus and look at an interesting map and discuss the map and what it says, not what you want to talk about.

      • Yes, you CAN go ahead and wallow in some sort of inapplicable fantasy of ‘natural’ fire but, ‘pining’ for a pre-human landscape doesn’t do us much good in today’s real world. Humans have managed California’s landscapes since the last Ice Age receded.

        • Larry, again you can’t seem to respond respectfully to anyone who has a different view from you, a chronic problem here.

          And again, the map is just a map of lightning flashes. The point that was clearly made above, one that you do not seem to be able see, is that the map shows…
          1. Where there’s a lot of lightning.
          2. Where there’s not a lot of lightning.

          Then we have…
          3. Lightning is the primary ignition source for natural fires (fires not caused by humans).
          4. Natural fire regime patterns evolved long before humans arrived.

          So, once the associated communities are established, they can only continue to exist under the fire regimes to which they are adapted. We don’t know the lightning patterns of 25,000 years ago, but we do know that where you find a lot of lightning today is usually where you also find frequent, low severity fire regimes. Curious, isn’t it?

          And to repeat:
          5. This has nothing to do with humans or pining for ages of long ago. Why do you keep repeating things that were never referred to in the original post?

          • THIS is how you marginalize your own arguments. You clearly ignore fire-adapted plant communities, saying that before humans, fires didn’t happen very often. It’s a ridiculous premise, and intelligent people see the difference.

            • I don’t believe Richard Halsey is saying this at all, Larry. We also all know that fire-adapted plant communities run the spectrum from those adapted to high-frequency, low-severity fires to those adapted to low-frequency, high-severity fires.

  9. So we all agree that this is not a map of “natural fire return intervals,” and I question whether that inference is possible given the “other variables involved.” For example,

    “Some studies have investigated the relationship between flash polarity and lightning ignition (Fuquay 1980, 1982), while others have suggested that fire occurrence is correlated strongly to the total number of CG lightning strikes (Meisner et al. 1993). Climatologically, however, when fire starts were compared with strike locations, there was little or no correlation between positive, negative, or total strike locations (Fig. 1). This lack of correlation suggests that fire starts coincide more closely with available fuels than with the number or charge of lightning strikes, that some other characteristic of lightning influences ignition potential, or that the fire start data simply are not sufficiently accurate for comparison.” (And then you have to get from “fire starts” to the extent and severity of the fires, which are probably of most interest and introduce even more variables.)

    • No, we can’t agree.

      Again, can you or anyone here please offer up a place on this map where an ecosystem with a high frequency, low severity fire regime exists where there is a 0-.75 flash density?

      • Yes, all of the ponderosa forests in OR and WA on the east slope of the cascade mountains. Maybe this map isn’t detailed enough, but I don’t see of light blue (0.75 to 1.5) until we get over to the Blue mountains in OR and the Colville NF in WA. The entire east slope of the cascades is high frequency.

        • RE: “The entire east slope of the cascades is high frequency.”

          If we take that statement literally, it’s just way, way too broad of a brush. If, by “the entire east slope of the Cascades” you mean from the east side of the Cascade crest down roughly Highway 97 through Washington and Oregon the fire regimes (and tree species composition) in this large area would vary significantly in spots based on a variety of factors including elevation, slope and aspect.

  10. Thanks for the discussion. I have learned some things and acquired avenues for further research.
    I wish though these discussions could be conducted without personal rancor.

  11. Here’s another one about fire return intervals being determined/influenced by Native Americans.. also cites from early 20th century studies..
    “Coastal valleys and mountains and interior mountains are also typical of the Central Coast bioregion. Burning by Native Americans along the central coast shortened fire return intervals in grasslands and adjacent forests (Davis and Borchert 2006).”

    • Yes, burning by Native Americans definitely changed the landscape and likely contributed to the destruction and ultimate loss of native shrublands, especially along California’s central coast.

      But again, the map posted has NOTHING to do with Native Americans. It has to do with the amount of lightning on the natural landscape. Lighting is the primary source of ignition on the natural landscape. Therefore, it is a good proxy for natural fire regimes on the natural landscape prior to the arrival of human beings.

      Here’s the research on how Native Californian’s likely negatively impacted native plant communities on the central coast:

  12. Caroline et. al.: People get offensive when they get frustrated. Sometimes it’s frustration because they can’t get their knowledge of well validated science across. Sometimes the frustration comes when their pet unproven theories are questioned and, especially so, when they have staked their reputations on those theories. Most of us here fit into one of those two categories.

    1) Matthew – Original Post: “show them this map. The natural fire return interval in California is pretty low… from nothing to pretty darn infrequent when compared to the rest of the country.”
    —> CONTRADICTION from your 11/25 6:29pm response to Jim Ranscon: “No, I personally don’t think that a map of year round lightning density (regardless of time of year) is a surrogate (or has an absolute direct correlation) for fire return interval.”
    —> Which is it?

    2) Richard you say: “As I wrote earlier, the map shows lightning frequency and its relation to natural fire return intervals.”
    —> Nothing on the map says anything about how a 10 year lightning frequency (Flash Density) map has anything to do with historical or future fire return intervals. One of your comments explains how you came to deduce that it does but, as Jon explains so well, your deduction Leaves too many variables out.
    —> Your statement “Natural fire regime patterns evolved long before humans arrived.” implies that natural forests and climate are static. There is a little thing called “succession” that says forest types change due to disturbances, climate change and reproductive intolerance to shade.
    —> Expanding on what others said above, the map and your theory would imply that everything east of the Rockies should have very short natural fire return intervals since flash density is much higher than in the three west coast states. It ain’t so.

    3) Richard you say: “Larry, good grief. The map is not showing anything other than lightning frequencies. Of course there are other variables involved.”
    —> So why do you keep insisting on using a gross oversimplification like: “So yes, lightning frequency is an excellent indicator of natural fire return intervals” when you agree that “there are other variables involved.” Please qualify your “excellent indicator of natural fire return intervals” statement because it is confounded and way too broad for most of us to swallow as is.

    4) Richard you tell Larry: “Just for a moment, step away from your forest management focus”. Then you ask “Why is Jim still able to post here?”. Then you tell me “Gil, how did anything in this map suggest anything about “hands off” management?”
    1. You don’t control the conversation even if it is your map. Not even if it was your post. I tried a long time ago and found it futile. People have opinions &/ facts that come to mind because something said triggered their mind.
    2. As my first paragraph in this comment states these kind of discussions are prone to lead to frustration and popping off on both sides of the disagreement. In my many years of participation in this blog site, Sharon and a very few others are the only ones who haven’t popped off. If we excluded those who pop off, there wouldn’t be any participants for this blog site to serve as a place to attempt to exchange ideas and provide information to those observing from a distance.
    3. As the comments show, many of us agree with Jim yet some don’t seem to want to recognize and respect that difference of opinion and the examples that have been given contrary to your thesis.
    4. In one of your comments you say: “Natural fire regime patterns evolved long before humans arrived.” So I appear to have been correct in being concerned in my earliest previous comment here that there was a possibility of an inference that “natural” is “hands off” i.e. no humans around. In addition, the present day vernacular “Natural forest” can have only two interpretations: 1) a naturally regenerated stand which will be managed at a latter time as objectives dictate or 2) a naturally regenerated stand that will receive no intervention at the hands of humans i.e. “Hands off”. So it was entirely appropriate in my prior comment to address “hands off” natural forests. Does your definition of natural agree with the vernacular and which of the two options did you mean? If not what is your detailed definition of “natural”
    I am also concerned about anyone misinterpreting this discussion thread as an endorsement for more “hands off” / “natural” public forests in places where risk reduction management would be efficacious. High fire probability areas like in and around WUI areas and public access roads with any traffic level are areas where management is desirable as prioritized by level of risk and available federal resources. This is the very reason that neither Larry, I and many others can not step away from our “forest management focus”. We have a hard time understanding those who down play the need for sustainable forest practices. To paraphrase and amplify Larry, we focus on recognizing and making high risk situations more tolerable because that is what will save the most lives in the long run. We don’t focus on some supposition that applies to prehuman times since those times no longer exist.

  13. I found the map interesting, but not particularly useful, since lightning strikes in super-dry droughty western forests, compounded with steep terrain and daily and seasonal winds, can have more profound effects than in, say, Florida. Indeed, lightning fires before fire suppression may have smoldered for months over the winter and re-ignited the following summer. Are you really denying that fire is a common factor in the dry western forests?

    I did a quick GIS exercise of one forest in CA using a historic fire database, which goes back to 1908, and found lightning accounted for about 12% of the total acreage burned. And that’s after the Sierra was slicked off during the gold rush, subsequent fire suppression, heavy secondary logging, drunken miners, powerlines, RVs, and the general effects of Americans and cities. Prior to the gold rush, the effect of lightning fires was likely much more extensive, as it was unchecked by pavement, suppression, or recent human-caused fires.

    A recent article said one storm in September resulted in 19k lightning strikes in northern California- they happen a lot and they aren’t all at high elevation. 1987 was a banner year for lightning fires in CA.

    • Roy, if you were up for it, I’d be interested in guest post relating what Leiburg observed in that part of the Sierra in terms of logging and fire and then your GIS exercise. It’s interesting to me that both Native American burning and cutting (as you say, “slicked off”) and burns during the 1850-1900 period in the Sierra tend to not be discussed much.


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