Yosemite Wildfire Study

While browsing for historical fire maps, I ran across this interesting study of Yosemite wildfire issues. I scanned some of the study and felt it would be useful information.


I didn’t know that there are fewer individual and less severe wildfires in the early season, due to snowpack’s effect on thunderstorm development. The Forest Service land, where I took this 1990 picture of the A-Rock Fire, has burned 13 times in the last 100 years. Why did this particular wildfire kill so much old growth, when previous uncontrolled fires did not?


You can also see the fire’s “twin”, across the canyon. It also has suffered a re-burn, although it was the Park Service who let a fire get out of hand, on that incident too. The A-Rock re-burned when a prescribed fire was lit, and lost, within an hour of ignition. The Meadow Fire burned for weeks, costing $17 million, closing the Park during the height of tourist season. The Forest Service portion of the A-Rock Fire hasn’t re-burned, yet.

14 thoughts on “Yosemite Wildfire Study”

  1. Too early to tell about ecological impacts. How hot is it? Are we looking at low to moderate severity or something worse? In my simple minded way, I can accept moderate severity burns from an ecological standpoint but in most places prefer not to see a really hot fire. Like many people, I subscribed to the idea that in times past there were lots of fires, and in many areas they did burn hot as hell such as LP, generally fires did not kill as many trees.

    But that idea may be a too optimistic view, work by Baker and others contends that pre settlement fires did burn hot even in low elevation ponderosa low severity regimes and the paradigm of cool underburns and mixed severity burns I had in my head was hardly accurate.

    Bob’s comments about huge west side Oregon blazes in 19th century are accurate

    • But just because it burned that way in the past does not mean that sedimentation and hydophobic soils were/are a good thing. It’s not entirely about direct vegetation impacts.

    • greg: Don’t forget about the 1902 and 1910 fire complexes, the 1918 Cedar Butte Fire, the 1933-1951 Tillamook 6-year jinx fires, the 1936 Bandon Fire, the 1966 Oxbow Fire, and the 1987 Silver Complex — lots of 20th century action, too!

      Also –please read some of the discussions of Baker’s work on this blog. Not too sure his conclusions are actually a logical result of his methods and findings. There seems to be a leap of faith in there that is hard to understand, based on the data he reviews.

  2. Only one òne of those I know well is silver and it was a low severity burn with only 15% of area in high severity/mỏrtality . An ecoburn I liked to call it. As for the others, I have no idea. But most of the Klamath Siskiyou is considered a mĩxed severity regime which can go either way so who knows what is “normal” thêre.

    This is a good review.


    • Ironically, the comments there are interesting in a different way, from other mainstream publications. I saw this entry:

      “We need to learn what we can from past mistakes, and do what we can to accommodate both traditional and contemporary values. But ecosystem management is fraught with fragmentary knowledge, overlapping jurisdictions and conflicting interests. Blaming anyone or anything in particular for the long-incubated crisis of the moment might be ephemerally cathartic, but it doesn’t change the situation on the ground.”

      The fire in the canyon is a “natural” event, even it was human-caused. If it didn’t burn this year, it would burn during another dry year, with a well-placed lightning strike. I suspect that Indians knew that canyon wildfires were dangerous, and “mitigated” their lives and environment.

  3. I’m not at all familiar with the Sierra Nevada forests…so maybe Larry could “expand” on what I say. Is the following “typical” of these forests?

    I was just looking at an EA for the Reynolds Creek Ecological Restoration Project on the Stanislaus NF.(you can tell you’re in Cali…it seems all the timber sale projects are called “ecological restoration projects” LOL). This project is on the north edge of the Rim Fire, just west of Cherry Lake…and from looking at Inciweb has probably burned by now.

    On page 58 there is a table comparing “average trees per acre” today VS. 1911. In 1911 there were only 30 TPA total…which sounds standard for the frequent fire regime. As usual with ALL “frequent fire” national forests in the west, there are more TPA now…but what’s striking is there are 50% more TPA larger than 30″ DBh. Today there are 16 TPA > 30″ vs. 10 in 1911. Today there are 34 TPA in the 20″-30″ class where there were only 9 in 1911. And there are 66 TPA in the 10″-20″ today VS. 4 in 1911. Sounds pretty “merchantable” to me. The fire suppression generation of trees.

    Once again, amidst all the current en vogue clamour about how we “should have let it burn for the last 100 years,” it would appear there are MORE large diameter trees today than 100 years ago. I LOVE the following caveat that the USFS inserted below the table. “due to sensitive species, “climate change,” and other factors, it is unrealistic for the desired condition to mimic 1911 densities.” Instead of 30 TPA that were “natural,” they were gonna leave 90 TPA…because of climate change! LOL.

    Once again…folks just can’t handle the truth of the pre-settlement forest.

    • Well, simply because we cannot log trees over 30″ dbh, we cannot expect to meet historical stocking levels, in some areas. Old growth can be found almost everywhere in the Sierra Nevada. Back in 2000, I worked on laying out plantation thinning units, directly west of Cherry Lake. In between those plantations are brushfields that were allowed to “recover” on their own. That sure made flagging and painting those boundaries a pain (mostly due to the thick whitethorn and manzanita. There are some patches of private land in that area, which burned in the same fire back in 1971.

      The Stanislaus NF rarely has met their timber goals, even when given extra money to do so.

  4. Oh…and since I’m a map junkie…Who owns that big block of private land just west of Cherry Lake? The fire has burned through it…but it looks like it was intensively managed with some clearcuts but a lot of nice thinning. Will be interesting to see how it’s post fire mortality fares.

    I know it’s a holiday…but could you have that on my desk Tuesday morning Larry? And Sharon…we’ll need you to come into work on Sunday to “play some catch up,” sooo…could you see to it that we get those damn BAER post fire “vegetation mortality” maps sooner. Just make it happen would you? I’ll expect it on my desk Tuesday morning when I get back from my cabin on the lake. (I’m sorry! It’s late, I’m tired, and I had to cancel my vacation because of work load…so I’m just a bit “Owley.”)

  5. Interesting Factoid:
    “This past summer reflects a decade – long trend of severe fire activity in the United States. This decade fires have burned 57% more land than in the previous four decades; the fire season has expanded by two months; and the average size of fires has increased by a factor of five since the 1970s”
    I don’t see where all of these fancy words and demands for Uncle Sam to cough up more money are going to get any traction. I see less money coming down the pike.

  6. Some time ago, I met a Park Service employee, who said she had done much Rx fire in Yosemite. Are there any observations out there of people, who have been to the Rim Fire, that detected a difference of: “rates of spread”, “fire intensity”, or “tree mortality”, between the Rx area and the non-Rx area?

    • I have seen Wagtendonk being interviewed by the TV media. Most of the Park’s prescribed fires have been performed within the Valley. They do often let fires burn in the backcountry. Those upper elevation fires rarely burn more than a few thousand acres. It is those fires that start at lower elevations, where fuels are ample and dry, utilizing the upslope/upcanyon winds to rush the fire into a firestorm. Sometimes, the Park firefighters will let a fire burn too long, resulting in expensive emergency actions, and adverse impacts upon the land. Fire fighters should not have to tread this fine line between “natural” fires and “destructive” fires. If a fire has burned for 10 days, backing down a slope towards more flammable fuels (and human infrastructure), shouldn’t we step in and stop it from backing down? Or, should we light a backfire from the road, allowing it to gain speed and intensity, burning uphill, towards partially-burned fuels?


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