- Author: Susie Kocher
In the many forested areas where wildfires are currently burning, the question will soon arise: What should be done after the fire goes out? That depends on the severity of the burn and land owner goals.
For high severity burns where very few or no live trees remain to provide seed for the next generation, forest recovery can take a very long time. Typically forest landowners want to restore their lands to a forested condition as quickly as possible. In that case, an active approach can help them reach their goal sooner.
The California Tahoe Conservancy has just released a report on the outcomes of active restoration of 40 acres of Conservancy lands where all trees were killed by the 2007 Angora fire in South Lake Tahoe. That fire burned 3,100 forested acres as well as 250 homes.
Post-fire Conservancy goals were to re-establish a native forest, reduce hazards posed by dead trees, and avoid water quality impacts. Contractors cut large dead trees, skidded them to a landing, loaded them on a log truck and sent to a nearby mill. Some large dead trees were left on site to provide wildlife habitat. Small trees were ground up (masticated) and left on site to control erosion and suppress competing vegetation. Then one- to two-year-old native conifer seedlings were planted.
The report's authors estimate this active approach has hastened the return to a forested condition in the area by about 60 years. This is because planted seedlings are growing quickly while there are few naturally sprouting tree seedlings in adjacent untreated areas and these face competition from vigorously growing native brush that was stimulated by the wildfire. Soil monitoring showed no compaction by heavy equipment during tree removal and minimal soil erosion. Woody mulch left on site was also effective at suppressing brush to give newly planted tree seedlings a competitive edge.
Landowners looking for guidance on post-fire forest management are encouraged to download the free UC Cooperative Extension publication “Recovering from Wildfire: A Guide for California Landowners” and consult the UC Center for Forest Research and Outreach website at http://ucanr.edu/forestry.
- Editor: Sophie Kolding
- Author: Susie Kocher
Most people planning home improvement projects take into account how improvements will affect the home’s ability to withstand rain and weathering. In California we should also consider the threat of wildfire when planning home improvement projects this spring
Most homes that burn during wildfires are ignited by flying embers landing on combustible material on or near homes. A wildfire passes by a home quickly, usually in a few minutes, while the exposure to flying embers can last for an hour or more. Therefore, activities homeowners undertake to make their home less ignitable from embers do the most to ensure its survival.
The most important home upgrade homeowners can do to reduce wildfire risk is to replace wood shake roofs with Class A roofs. Single-paned windows should also be replaced with dual-pane windows (with at least one pane being tempered). Combustible siding can also be vulnerable, but replacing it with non-combustible siding is less important if you have done a good job of locating and maintaining vegetation near your home. Replacing combustible decks with noncombustible decking products will also reduce risk.
Even though these upgrades are expensive, they reduce the likelihood that you will experience the cost and trauma of losing a home in a wildfire. If you cannot afford to undertake these projects this year, there are less expensive projects you can take on to reduce wildfire risk. These center on maintaining your home in good condition by replacing worn boards , sealing cracks in locations where embers can enter the home, and protecting vulnerable areas with non-combustible materials and coverings.
Even if you have already upgraded your home to resist fire by installing a new roof, windows, or deck, it is important to maintain those home components in their proper condition so embers cannot gain entrance to the home. Creating defensible space by clearning flammable vegetation and debris is also crucial to reducing your wildfire risk. For more information on the performance of building materials in a wildfire, please see http://firecenter.berkeley.edu/ or www.extension.org/surviving_wildfire. For more on creation of defensible space, contact your local fire agency.
Homeowner installing screens under a deck to reduce the likelihood of ember intrusion
during a wildfire. Photo by Steve Quarles.
Suggested home maintenance projects to reduce wildfire risk
- Plug roof openings: Install end-stops (bird-stops) at the edge of your roof if it has a gap between the roof and the sheathing (as with a clay barrel tile roof).
- Protect roof edges: Install metal angle flashing at the roof edge to protect the roof sheathing and fascia board, especially if there are gutters attached that can hold combustible pine needles. Even a Class A roof cannot protect the wood sheathing under it if the roof edge is unprotected.
- Protect roof eaves: “Box in” your open eaves with sheathing, such as a fiber cement soffit or higher grade plywood.
- Skylights: Particularly on steep or flat roofs, replace plastic skylights with skylights that use tempered glass in the outer pane.
- Maintain siding: Fill gaps in siding and trim materials with a qood quality caulk help keep out embers. Replace warped or degraded siding.
- Protect vents: Inspect the vents into your attic and crawl space. Make sure the screens are in good condition. Replace ¼ inch mesh screen with 1/8 inch mesh screening.
- Maintain decks: Replace deck boards that are less than an inch thick with two inch thick boards. Remove combustible materials from under the deck.
- Protect combustible siding: Install metal flashing between a deck and combustible siding to protect it from accumulated debris that can ignite during ember attack.
- Remove flammable material from under decks: If your deck is made from wood or wood-plastic lumber decking, remove combustibles (firewood, lumber, etc.) from under the deck.
- Replace gates: Replace combustible gates and sections of wooden fences within five feet of the house with noncombustible materials and components.
- Adjust garage doors: Your garage door can be very “leaky” to embers. Since most people store combustibles in their garage, make sure your garage door is well sealed at the edges.
- Editor: Sophie Kolding
- Contributor: Max Moritz
Although wildland fires are a natural part of forest ecosystems, they can interefere with the planning of land-management activities and may have an array of anthropogenic factors. The article, Spatial variability in wildfire probability across the western United States from the International Journal of Wildland Fire, uses fire obsertvations to produce detailed estimates of wildfire probability, of both natural and anthropogenic factors. The International Journal of Wildland Fire publishes papers that advance basic and applied research concerning wildland fire. The Journal wishes to attract papers on a broad range of wildland fire issues that may include subjects beyond the range of papers published in recent issues. The Journal has an international perspective, since wildland fire plays a major social, economic and ecological role around the globe. The authors of the article, Spatial variability in wildfire probability across the western United States, include Marc-Andre Parisien, Susan Snetsinger, Jonathan A. Greenberg, Cara R. Nelson, Tania Schoennagel, Solomon Z. Dobrowski and Max Moritz.
Here is the article's abstract, along with figures and their descriptions:
'Despite growing knowledge of fire-environment linkages in the western USA, obtaining reliable estimates of relative wildfire likelihood remains a work in progress. The purpose of this study is to use updated fire observations during a 25-year period and a wide array of environmental variables in a statistical framework to produce high-resolution estimates of wildfire probability. Using the MaxEnt modeling technique, point-source fire observations that were sampled from area burned during the 1984-2008 time period were related to explanatory variables representing ignitions, flammable vegetation (i.e. fuels), climate and topography. Model results were used to produce spatially explicit predictions of wildfire probability. To assess the effect of humans on the spatial patterns of wildfire likelihood, we built an alternative model that excluded all variables having a strong anthropogenic imprint. Results showed that wildfire probability in the western USA is far from uniform, with different areas responding to different environmental drivers. The effect of anthropogenic factors on wildfire probability varied by region but, on the whole, humans appear to inhibit fire activity in the western USA. Our results not only provide what appear to be robust predictions of wildfire likelihood, but also enhance understanding of long-term controls on wildfire activity. In addition, our wildfire probability maps provide better information for strategic planning of land-management activities, especially where fire regime knowledge is sparse.'
Figure 1. The study area showing the 11 western USA states, elevation, road density (computed using a 1000-hacircular window), mean annual precipitation, mean annual temperature and land cover that was generalized from the National Gap Analysis.
Figure 2. Mean predicted wildfire probability (based on 25 model replicates) for the Full model (a); the Non-anthropogenic model (b); the absolute change (c); and the relative change (d) from the Full model to the Non-anthropogenic model, whereby green indicates an increase and blue represents a decrease in wildfire probability as a result of human-influenced variables.
To view the entire article, please visit the website:
- Posted By: Jaime Adler
- Written by: Susie Kocher, UCCE Advisor
Wildfire Summit pulls together Tahoe basin residents and agencies on the fourth anniversary of the 2007 Angora fire to improve implementation of defensible space
The Lake Tahoe Wildfire Summit was held in Tahoe City on June 24th, 2011, four years after the Angora fire which started on June 24th, 2007 in South Lake Tahoe. The summit drew together over 100 basin residents, agency staff and policy makers to focus on ways to reduce wildfire risks to Tahoe homes and communities. Presentations centered on wildfire issues in the Tahoe Basin and how to reduce risk to homes and communities by creating defensible space, improving building materials and design, and implementing forest fuels reduction projects. Participants also went on field trips to the nearby Washoe fire, to a forest fuels reduction project implemented at Granlibakken resort (the hosting venue), and to a nearby neighborhood to examine the flammability of home construction.
After reaching a highpoint in 2007 due to the Angora fire, the level of concern about wildfire and motivation to do defensible space seems to be tapering off at the lake according to many fire agency staff. Participants cited residents’ and homeowners’ attitudes as the foremost barrier, saying that people don’t care about fire hazards, don’t think of natural vegetation as needing maintenance, or would rather recreate than do yard work. This attitude may be deeply ingrained at Lake Tahoe, a community where leisure and recreation in the “natural” outdoor environment is deeply valued.
Lack of understanding about the issue and denial that a wildfire could happen again were also cited with some reporting time they had been told by locals that Tahoe had an “asbestos” forest and wouldn’t burn. Other concerns are that vegetation removal for defensible space will look unsightly or reduce privacy. Also, there is a perception that defensible space actions are illegal or clash with water quality best management practice requirements required by local and regional government to preserve Lake Tahoe’s famed clarity.
Ownership patterns, including second home ownership and a high percentage of rental properties, reduce the opportunity and ability for some to complete defensible space. Costs are a factor for some residents, especially during the current recession (though there are currently rebate programs in place that can pay up to half of the cost of defensible space treatments). Disposing of materials can also be difficult.
Attendees at the Summit brainstormed and prioritized strategies to overcome these barriers to defensible space implementation. Education was cites as the major need to increase implementation. Education should focus on increasing awareness and understanding of the fire issue at Tahoe and highlighting the attractiveness of defensible landscapes. A major goal should be to develop a culture that doing defensible space is just a part of living at Lake Tahoe. Helping residents understand that defensible space is not only legal, it’s required and will eventually be enforced was also key. Following up with actual enforcement actions was identified as critical to this effort.
At the end of the day, all participants said the summit helped to clarify wildfire issues in the Tahoe Basin. 88% said it will help their communities work together to reduce wildfire risk and that they personally had a better idea of how to reduce wildfire hazards in their community.
Partner agencies included the seven local fire agencies in the basin, CalFire, the Nevada Division of Forestry (NDF), the Tahoe Regional Planning Agency (TRPA), the US Forest Service and both the University of California and University of Nevada Cooperative Extension. Funding for the event was provided by the NDF, TRPA, fire resistant construction material manufactures, and local defensible space contractors.
For a full account of the event, please download the Summit Report
For more information on how to implement defensible space at Lake Tahoe, go to: www.livingwithfire.info/tahoe
- Posted By: Jaime Adler
- Written by: Steve Quarles, UCCE Forest Specialist
The ASTM E05.14 Subcommittee on Exterior Fire met today. Task groups that are developing standard test methods to evaluate vents and decking products updated the subcommittee on progress made since the last meeting (these committees meeting every six months, in early December and early June). All of these draft standards are in some stage of balloting at the subcommittee or main committee level.
Professor Joe Urbas, University of North Carolina-Charlotte, gave a presentation to the subcommittee on a research project that he has been working on. Professor Urbas has been evaluating the effectiveness of wetting agents applied to vegetation and building components in resisting radiant heat exposures. The wetting agents he evaluated included water, foam, and a gel product. He tested the vegetation and building components (e.g., siding) with heat from a radiant panel immediately after and one hour after applying the wetting agent. In conducting this research project, Urbas has developed a performance measure that he calls the critical flux for fire growth (CFFG) – the heat flux that will result in the ignition and growth of fire on the vegetation or building material. The CFFG of a material is determined by exposing different specimens (of the same material) to different heat flux exposures, converging on the CFFG value. This has direct implications to homes and landscaping vegetation in wildfire prone areas and may provide a way to compare the performance of vegetation. Professor Urbas will be leading a task group to develop a standard test method using what he has learned in this research project.