REPOST: USFS research confirms most CA fires occur in areas of WUI with sparse vegetation, but more people

Photo by LA Times

[NOTE: I wrote the following post on this blog on October 23, 2019 highlighting new research by a U.S. Department of Agriculture Forest Service scientist and University of Wisconsin-Madison partners. I’m reposting it 11 months later because it seems relevant to many of the recent discussions on the blog.]

This morning I got an email from U.S. Forest Service Research News, which including a link to this new research from the USFS and partners concerning wildfires in California.

While the research may be surprising to some, it’s not at all surprising to many of us who have said the same thing going back a few decades now. We’ve had perhaps over a hundred debates about this on the blog over the years. Heck, Dr. Jack Cohen’s research documented much of this going back into the 1980s, if not even earlier. Richard Halsey and his California Chaparral Institute have been also talking about these issues for at least 20 years. And those of us who’ve been branded as “environmental terrorist groups” – and blamed for California wildfires by the likes of former Interior Secretary Ryan Zinke – have been also trying to get the public and policy makers to understand the dynamics at play for decades as well.

Remember, it’s been very common for politicians from through the country (but especially the West) to use wildfires in California as the reason why we need to dramatically increase logging on our public lands by systematically weakening bedrock environmental laws. While that may make for good politics when people turn on their TV’s and see flames, it doesn’t make for good policy that will protect communities, firefighters and save lives and money.

Most California Fires Occur in Area of Wildland-urban Interface with Less Fuel and More People

Madison, WI, September 24, 2019 – In California, the state with more building destruction by wildfire than all of the other states combined, new research by a U.S. Department of Agriculture Forest Service scientist and University of Wisconsin-Madison partners found something surprising. Over nearly three decades, half of all buildings destroyed by wildfire in California were located in an area that is described as having less of the grasses, bushes and trees that are thought to fuel fire in the wildland-urban interface, or WUI.

The study by H. Anu Kramer with Forest Service scientist Miranda Mockrin and colleagues, “High wildfire damage in interface communities in California,” notes that a portion of the WUI defined as “interface” and characterized by having more homes but relatively little wildland vegetation experienced half of the building losses due to wildfire but composed only 2 percent of the total area burned by the wildfires assessed in the study. The study was recently published in the International Journal of Wildland Fire and is available at: https://www.nrs.fs.fed.us/pubs/58348

California’s expansion of housing within and adjacent to wildland vegetation is not unique; the most recent assessment shows that the WUI now includes about one-third of homes in the United States. As wildfire management has become more complex, costly and dangerous, defining what constitutes WUI and defining more specific types of WUI has become more important as local communities strive to apply resources and policy-decisions where they will be most effective in saving lives and property.

The Federal definition of WUI describes two specific areas: “interface” WUI includes developed areas that have sparse or no wildland vegetation, but are within close proximity of a large patch of wildland. “Intermix” WUI, on the other hand, is defined as the area where houses and wildland vegetation directly intermingle. Both are separate from “rural” areas, which may be characterized by agricultural land and low-density housing and development (less than 1 house per 40 acres).

“Our findings show that WUI areas do experience the vast majority of all losses, with 82 percent of all buildings destroyed due to wildfire located in the WUI,” Mockrin said. “We were surprised to find 50 percent of all buildings lost to fire being destroyed in the interface portion of the WUI, however. Many risk reduction plans focus on natural vegetation fueling fire, but in the interface WUI where so much of the destruction is occurring, we have to consider finer-grained fuels such as wood piles, propane tanks, and cars.”

Study findings suggest that wildfires are still rare in urban areas. The Tubbs fire that struck Santa Rosa, Calif., in 2017 was similar to other California wildfires in that the majority of buildings lost in the fire were located in the WUI; however, the Tubbs Fire was unique in having 25 percent of all destruction occurring in urban areas. In comparison, 4 percent of destruction occurred within urban areas in other California fires. Other recent and highly destructive fires, including the 2018 Carr, Camp and Woolsey fires, included no urban area within their perimeters, exemplifying the rarity of the Tubbs’ building destruction in urban areas.

“Although the Tubbs fire was not the norm, it seems like every fall there is a new record-setting fire in California, with three of the five most destructive fires in state history having burned in the last 5 years and the deadliest California fire (the Camp fire) burning last year,” Kramer said. “These fires are fueled by the homes themselves, landscaping, and other man-made fuels that are seldom included in the fire models that are used to predict these fires. Our work highlights the importance of studying and mitigating the fuels in these interface WUI areas in California where most of the destruction is occurring.”

In addition to solidifying definitions of interface and intermix WUI so communities can address their different attributes in wildland fire planning, researchers suggest that fire behavior models should be revisited.

The study was co-authored by Volker Radeloff of the University of Wisconsin-Madison and Patricia Alexandre of the University of Lisbon.

4 thoughts on “REPOST: USFS research confirms most CA fires occur in areas of WUI with sparse vegetation, but more people”

  1. A few of thoughts on this…
    1. It seems to me that this study shows damage occurs across all areas (urban less, rural, WUI interface and intermix.) I think we knew that.
    “Rural areas encompassed the majority of the area burned by destructive wildfires, and ternary plots revealed that half of destructive California wildfires destroyed buildings primarily in rural areas; yet these fires threatened and destroyed few buildings overall owing to low building density (Fig. 1d; Fig. 3). The rate of destruction in rural areas was also high. Buildings in non-WUI, rural areas with wildland vegetation certainly remain vulnerable to wildfires as evidenced by this high overall destruction rate (see also Kramer et al. 2018). In many cases, the reason why these rural areas with wildland vegetation are not mapped as WUI is that their housing density is too low (Radeloff et al. 2018). A consistent threshold that differentiates WUI from rural areas is important, both in comparing results of different studies, and in relating results to management actions on the ground.
    Recent work by Syphard et al. (2019) suggested that destruction by wildfire in California was most prevalent in rural as opposed to WUI or urban areas. However, they found an overall mean housing density of 0.08 to 2.01 structures ha1 for destroyed suggesting that what we define as WUI matches what they define as rural (Stewart et al. 2007; Syphard et al. 2019). Tracking these housing densities consistently across studies is essential for comparing wildfire management, losses and policy implications in the diversity of settings where wildfire poses a threat to housing development (Stewart et al.2007; Platt 2010). Although other WUI definitions exist, those described by the Federal Register (USDA and USDI 2001) are used nationally and provide a consistent framework on which to evaluate the WUI. This does not mean that these definitions are set in stone, however, and future definitions could further advance the ways that WUI is mapped and regulated.”

    I could be convinced, but right now I’m not sure that having a standard definition really helps. People don’t want their houses to burn down no matter where they live.

    4. “Our findings show that WUI areas do experience the vast majority of all losses, with 82 percent of all buildings destroyed due to wildfire located in the WUI,” Mockrin said. “We were surprised to find 50 percent of all buildings lost to fire being destroyed in the interface portion of the WUI, however. Many risk reduction plans focus on natural vegetation fueling fire, but in the interface WUI where so much of the destruction is occurring, we have to consider finer-grained fuels such as wood piles, propane tanks, and cars.”

    I don’t think the importance of wood piles and propane tanks has slipped by folks working on wildfire mitigation.. as per this link https://static.colostate.edu/client-files/csfs/pdfs/FIRE2012_1_DspaceQuickGuide.pdf
    To the Colorado State Forest Service “Protecting Your Home from Wildfire: Creating Wildfire-Defensible Zones”.

    Of course, I can’t judge how good fire models are in the WUI. I wonder whether there is a suppression-folk-derived list of their needs developed each year?

    The last sentence of the paper is hard to argue with, though. My italics.

    “A combination of improved modelling, research into wildfire risk in densely built areas, fuel reduction in the home ignition zone, use of fire-resistant landscaping and building materials, strategic placement of fuel reduction treatments around communities, and community education and planning of building locations in regards to wildfire could lead to policies and mitigation that reduce wildfire risk in the interface WUI.”

    Reply
  2. The title of this post is “USFS research confirms most CA fires occur in areas of WUI with sparse vegetation, but more people”. Absolutely nowhere in the linked article did the authors come to this conclusion. I don’t know if you are intentionally trying to deceive the reader, you failed to actually read the article, or you lack the ability to interpret the findings. The authors did find 82 percent of all buildings destroyed by wildfire from 1985-2013 were located in the WUI and that 50 percent of all buildings lost to fire being were in the interface portion of the WUI. Despite the fact that 50% of building loss was in the interface it only accounted for 2% of area burned. The authors actually found that very little of CA fires occur in the WUI with sparse vegetation but more people but those few fires resulted in ½ the building loss.

    Reply
    • Hi Patrick: Thanks for your comment.

      The title of the blog post is: USFS research confirms most CA fires occur in areas of WUI with sparse vegetation, but more people

      The title of the USFS article is: Most California Fires Occur in Area of Wildland-urban Interface with Less Fuel and More People

      Furthermore, I not only provided a clear link to the actual study, but I also linked to the original article from the U.S. Forest Service’s Northern Research Station and went one step further and pasted the entire article from the USFS into the blog post.

      Reply
  3. Eugene OR here. We own 400 acres of timberland and will discuss that but first… Block after block of totally burned homes in an urbanized area is not primarily caused by lack of forest management or “climate change”. Chicago Fire of 1871. It was very hot, dry and windy. Much of Chicago back then was wooden buildings with shake or tar roofs. There were other fires so resources were spread thin. Legend has it a cow kicked over an oil lamp and the fire became uncontrolled and an URBAN FIRESTORM happened…something since then thought to be ‘impossible’ outside of war due to better building materials and codes. Future Problem? Sociopaths “strategically” setting fires on hot dry days in order to burn down cities.

    Two years ago, there was a near-record snow that downed significant timber. A year or two before that, a bad ice storm did much the same. With 400 acres, we put out the call for a logger and the first thing we hear is “log prices are way down due to oversupply”. The logger recommended a professional forester and we went that route. We had a thinning contract with a 45% split to Owners, 65% to Logger …. well, they ended up doing a clearcut and had we known we would have negotiated better splits. I was rather p.o.’ed about it, even mentioned it to the logger. A couple days later, I felt lucky we clearcut…they finished hauling out the last of the logs the prior week.

    We are hearing hushed rumors that more people DID NOT make it out than did. We know FEMA teams are up there with cadaver dogs. The hills were FULL of rather old and/or infirm people. There were a lot of people living in campers behind a relative’s home. Many of them moved up there when they were young, 1 – 5 acres is a common rural-residential lot. Over the years, vegetation slowly but steadily encroached as people and homes got older. ‘Nobody’ clears dead wood or mows/plows dry fields. It is generally not economically feasible for a small landowner to do anything about their trees, which are looked at as landscaping…not timber.

    My personal opinion based on viewing videos is that ASPHALT ROOFS were the primary vector of the urban firestorms we experienced.

    Reply

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