Reposted from the UCANR Green Blog.
Hike off-trail through most any part of the Sierra Nevada and you may find yourself losing your hat to a low hanging branch, your shoe to a thicket of dead and dying brush, or your companion to the crevice hidden by the wall of young trees.
There is no doubt that the forests of the Sierra Nevada, while amazingly beautiful, have grown dense with vegetation. Consequently, forests have become increasingly susceptible to high severity fires, which negatively impact the forest's overall health and our ability to enjoy it.
There is a relationship between a healthy forest and its density. The denser the forest, the more competition individual trees have for valuable resources, such as water, light and nutrients. The effects of competition on tree growth and death are profound – the more trees per acre, the smaller the diameter of the individual trees (meaning less growth) and the higher the likelihood trees will be negatively impacted by pests, diseases, and poor health, ultimately leading to tree mortality. Theories in ecology, supported by field data and statistical analysis, predict that some trees will outperform others and the difference in performance increases with crowding. Unfortunately, evidence suggests that excess density is causing increased mortality in the Sierra.
John Battles, forestry professor at UC Berkeley and member of the Sierra Nevada Adaptive Management Project (SNAMP), is leading a team of UC Berkeley researchers and graduate students in developing vulnerability profiles that will help to quantify individual trees' probability of survival. The growth response of individual trees is the primary measure of forest health in the SNAMP study. The team believes growth is an excellent indicator of tree vitality and that a necessary (but not sufficient) condition for a healthy forest is healthy trees.
The team collected and processed more than 12,000 tree cores to develop long term growth and vulnerability profiles for different tree species. Their results supported the accepted notion that, in general, good growth was an indicator of good health. However, they also found that "bad years," when growth was substantially lower than normal, were strong predictors of death. In addition, they reported that bad years had a cumulative impact that spanned decades. In other words, the best predictor of potential death was for a tree to experience two or more bad years over the most recent 20 – or even 40 – years. The team has been working to translate these relationships between tree growth and survival to produce a vulnerability index by species and size. One goal is to have some sense on how vulnerable a stand is before many trees start to die.
Another key question being asked by SNAMP researchers is whether fuels treatment projects designed to modify fire behavior also improve forest health. Battles and his team hypothesize that thinning a dense forest will improve individual tree and overall forest health, as well as reducing fire risk. Resilience, or the capacity to recover from adverse conditions, is the goal. Histories captured in tree core samples show that trees can survive adverse conditions such as fire and drought. While studies have shown that properly implemented fuel treatments are effective at reducing hazardous fire potential, there are secondary ecological effects that can impact forest resilience either positively or negatively depending on the treatment type, timing and intensity. In a study at the UC Blodgett Forest Research Station, researcher Brandon Collins and others looked at large, dominant tree growth responses, measured seven years after the implementation of some of the most common fuel treatments, to estimate that forest's health. Across the five tree species analyzed, observed mortality and future vulnerability were consistently low in the areas where only mechanical treatment occurred. Fire-only treatment had results similar to areas that did not receive treatments for all species except Douglas-fir. Mechanical-plus-fire treatments, however, had high observed mortality and future vulnerability for white fir and sugarpine. Given that these large, dominant trees play a key role in terms of wildlife habitat, carbon sequestration and soil stability, these results have implications for understanding longer-term impacts of common fuel treatment types on forest resilience.
Through the analysis of tree core samples, Battles and his team hope to provide clarification on conditions that improve individual tree health and the overall health of the forest. The final report on SNAMP, with the results of the forest health study described here, will be available May 31, 2015, athttp://snamp.cnr.berkeley.edu/.
- Author: jeannette warnert
- Posted by: Susie Kocher
Published on: October 28, 2014 on the UCANR Green Blog
After academics complete fire science research, the results often end up gathering dust on a shelf. UC Cooperative Extension is now playing a significant role in bridging the gap between wildland fire science and wildland managers across the United States.
“It is a classic disconnect,” said Susie Kocher, UC Cooperative Extension advisor in the Central Sierra office. “That's why Cooperative Extension was formed almost 100 years ago. Policymakers could see that research advances weren't being implemented on farms. The same thing has happened in natural resource management.”
For example, Kocher said, scientists have known since the 1960s that systematic fire suppression has many negative consequences, but it took a very long time to get that message into practice by agencies charged with managing wildfire.
“After the Great Burn of 1910, which killed 87 people, there was a public clamor to attack fire and treat it as an enemy,” Kocher said. “We've come a long way since then. Now land managers have a good understanding of how important it is to have low-intensity fire in Sierra forests.”
Fire agencies are now beginning to understand that they must pay attention to technology transfer. Kocher believes UC Cooperative Extension is a logical player in the process.
“Cooperative Extension is the exemplar,” Kocher said. “We try to get new and evolving understanding into the hands of people who use the information to made decisions – not just land managers, but the public and policy makers as well.”
Beginning in 2009, the federal Joint Fire Science Program created 15 regional fire science exchanges to accelerate awareness, understanding and use of wildland fire science. Scott Stephens, professor in the Department of Environmental Science, Policy and Management at UC Berkeley, leads the California consortium. Stacey S. Frederick serves as the consortium's full-time coordinator. Other UC academics involved are Kocher and Yana Valachovic, UCCE advisor in Humbolt and Del Norte counties.
Since its inception four years ago, the consortium has hosted webinars, conferences and symposia, and offered field consultations, field trips, tours, demonstrations and expertise. Another significant role of the group has been distilling academic fire science research reports into easy-to-read one-to two-page research briefs. To date, well over 100 briefs have been written by the consortium on a wide range of topics.
The California Fire Science Consortium maintains a comprehensive website that contains links to the research briefs, webinar recordings and information about upcoming events. The consortium also offers a twitter feed @cafirescience and Facebook pagehttps://www.facebook.com/CaliforniaFireScienceConsortium and you can sign up for their monthly newsletter here.
- 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: