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Posts Tagged: sudden oak death

Coast redwoods increasingly susceptible to fire damage

Fire consumes a once-healthy California redwood tree. (photo: USFS)
California’s renowned coast redwood trees, previously believed to be fireproof, are now more than four times more susceptible to wildfire injury in coastal forest areas infested with the sudden oak death pathogen. These redwoods are now as susceptible to wildfires as other trees.

Millions of trees, including tanoaks, coast live oak, California bay laurels, and many other forest species have been killed by sudden oak death in coastal areas of central and northern California, and Oregon. The pathogen, Phytophthora ramorum, was first linked to the massive tree death in the mid-1990s.

David Rizzo, professor in the Department of Plant Pathology at UC Davis, and his research team are studying how the coastal forest ecology is changing since sudden oak death appeared, and why coast redwoods (Sequoia sempervirens) are subsequently so much more susceptible to fire.

It is the presence of the sudden oak death pathogen in forests that poses heavier fire risks for redwoods.

“If redwoods didn’t live in forests affected by the disease, they could withstand fires just fine,” says Margaret Metz, a postdoctoral research scholar working with Rizzo.

Professor David Rizzo, UC Davis.
An initial explanation for the higher redwood mortality following wildfires is heavier fuel loads (such as fallen, dead branches from tanoaks) in forests affected by sudden oak death. Tanoak, Notholithocarpus densiflorus, is the primary host dying from sudden oak death and the main source of pathogen inoculum.

According to Rizzo, “The disease likely created more fuel for wildfires as dead tanoak branches fell. The loss of the oaks also would have decreased the amount of shade, drying out the forest and turning it into a tinder box, one not even redwoods could survive.”

A real key, though, is the finding that dead tanoaks, still standing, carry flames high into tree canopies, scorching the crowns of adjacent redwood trees. It’s this crown injury that is believed to have caused so many redwood trees to die in a number of fires that occurred in 2008.

Dead tanoaks in a redwood forest in the scientists’ California study area, pre-fire. (photo: Kerri Frangioso/UC Davis)
“Humans are causing widespread changes throughout our world, including greater wildfires related to changing climate and from increasing infectious disease due to more modes of transportation,” said Sam Scheiner of the National Science Foundation, which funded some of this research.

Rizzo, noting that an increase in fire severity is resulting from climate change and global movement of species, says, “There may be all sorts of consequences, among them, dead and dying coast redwoods.”

Additional information:

  • California's iconic redwoods in danger from fire and infectious disease. National Science Foundation report on Rizzo group’s work, August 2013
  • The effects of sudden oak death and wildfire on forest composition and dynamics in the Big Sur ecoregion of coastal California. General technical report
  • Ecology research article, Ecological Society of America
  • California Oak Mortality Task Force website
Posted on Wednesday, September 4, 2013 at 7:21 AM

Community effort beats back sudden oak death in Humboldt County

From left: Mark Rodgers, Julie Lydick, Pete Angwin, Rizzo, Valachovic, Phil Cannon, Ed Burton, Stephen Smith, Jack Marshall, Chris Nota and Russ Henly
Sudden oak death is a misnomer because it doesn't fell a tree like a lightning strike nor does the disease limit itself to oaks. Nonetheless, the moniker has stuck and UC scientists remain committed to containing the culprit. 

UC, federal and state agencies and landowners in Humboldt County recently received national recognition for their collaborative efforts to halt the spread of sudden oak death. Kathleen Merrigan, U.S. Department of Agriculture deputy secretary, praised the partnership during her visit to Davis on May 16.

Yana Valachovic, UC Cooperative Extension advisor in Humboldt County, and Dave Rizzo, professor in the Department of Plant Pathology at UC Davis, were joined at the USDA offices in Davis by their partners from USDA Forest Service, CAL FIRE and the Natural Resources Conservation Service to accept the Two Chiefs’ Partnership Award. Merrigan presented the award on behalf of the “two chiefs” – the head of NRCS and the head of the Forest Service.

For me, it was a pleasure not just to see Yana’s efforts rewarded, but also to see Dave Rizzo. About a decade has passed since the days I was on the phone and email almost daily forwarding reporter requests for interviews to the UC Davis plant pathologist. Rizzo was first to identify Phytophthera ramorum as the pathogen that causes sudden oak death in 2000.

Matteo Garbelotto of UC Berkeley demonstrates sudden oak death diagnosis and treatment for members of the media at the Berkeley campus.
As tens of thousands of California's beloved oaks fell to the disease, Rizzo and his colleague Matteo Garbelotto, UC Cooperative Extension specialist at UC Berkeley, an expert in forest pathology, were thrust into the limelight.

Although SOD doesn't make the news as frequently as it did in the early 2000s, it continues to spread. Garbelotto’s "SOD Blitz," his annual survey, found in 2011 that the rate of infection in trees between Napa and Carmel had grown as much as three times the rate of the previous year.

Since the disease was first reported in Marin County in 1995, it has been found in 14 coastal California counties and killed over 5 million tanoak, coast live oak, California black oak, Shreve oak and canyon live oak trees, according to the Forest Service.

UC Cooperative Extension employees were surprised in the spring of 2010 when routine  monitoring near the mouth of Redwood Creek in Humboldt County detected P. ramorum in leaf samples. It meant that trees were infected somewhere in the 200,000-acre watershed – more than 50 miles from the nearest known infestation and farther north than the pathogen had ever been detected in California.

UCCE staff coordinated a swift management response, embarking on the largest SOD management project ever to occur in California. They collaborated with the Forest Service, NRCS, CAL FIRE, tribes, local timber companies and private landowners to remove infected plant material. Rizzo pitched in with diagnostics for the project and matching funds to qualify for a federal grant.

From left, UCCE staff research associate Chris Lee, NRCS forester David Casey and Yana Valachovic inspect the treated area for signs of sudden oak death.
“We’ve been closely monitoring the disease for years and anticipating a scenario like Redwood Valley, so we were ready to take action and respond quickly,” said Valachovic, a forestry expert.

It’s still not clear how the pathogen got to Redwood Valley, said Valachovic, but it could threaten the dense tanoak forests of the surrounding area, killing trees and leaving behind dry brush, which could fuel wildfire. 

Landowner support has been critical to the success of the project, according to Valachovic. More than 20 landowners in the valley have allowed monitoring and treatment activities on their properties, recognizing that their cooperation may keep the disease from spreading to other areas.

The first phase of treatment is currently wrapping up, and UCCE is beginning to monitor project efficacy and watch for spread of the pathogen beyond project boundaries. The Yurok and Hoopa tribes will be paying close attention to this effort, as they are only a ridge away from the infestation. 

“Oaks are an important part of our culture and history, and we will do what we can to keep sudden oak death out of our forests,” says Ron Reed, a Yurok tribal forester.

The OakMapper app and website enable hikers and others to report SOD.
The Redwood Valley project highlights the benefits of people working together. If you would like to report sudden oak death, you can download the OakMapper smartphone app or submit reports at the OakMapper website. The website also features a map showing suspected and confirmed cases of sudden oak death.

Scientists, managers, regulators and policymakers will gather June 19-22, 2012, to discuss the latest news about the disease at the Fifth Sudden Oak Death Science Symposium in Petaluma.

For more information about sudden oak death disease, visit the California Oak Mortality Task Force website at www.suddenoakdeath.org.  

 

Posted on Wednesday, May 30, 2012 at 12:01 PM

Sudden oak death may increase wildfire fuel


SOD killed these trees, leaving dry fuel for a fire.
Sudden oak death (SOD) has been spreading among trees throughout coastal California and Oregon for the last 15 years. In that short time, the disease has infested 10 percent of California’s at-risk habitat and killed over a million tanoak and true oak trees, raising major concerns about the potential impacts of further pathogen spread. The disease is caused by the non-native pathogen Phytophthora ramorum.

Research by UC Cooperative Extension staff in Humboldt County shows that infection and oak mortality are only the beginning of the story, as the disease may increase forest fuels and put infested stands at higher risk of severe wildfire.

UC Cooperative Extension forest advisor Yana Valachovic, with assistance from Humboldt State University’s Forestry Department and CAL FIRE, found that in Douglas-fir-tanoak forests where high hardwood mortality is related to SOD, fuels can build up to hazardous levels on the forest floor over time. Their research documented fuels buildups in infected areas that could increase a wildfire’s flame length by 3 to 4 feet and double a wildfire’s rate of spread, depending on how much time has elapsed since initial infection.

The arrangement of dry leaves and dead branches pose serious challenges to firefighters in infested stands.
Not only does SOD alter fuel quantity in these forest types, but it can also affect moisture levels and the arrangements of fuels, posing serious challenges to firefighter response in infested stands. The disease drastically reduces the moisture content of foliage, and after trees die, they remain standing with dry, dead leaves for a few years – greatly increasing the likelihood of crown fire under extreme weather conditions.

Likewise, the increased fuels on the forest floor can take a long time to break down, posing a long-term fire hazard and additional risks to firefighters.

“The disease creates a hazardous fuels situation that is passed on to firefighters during wildfire," says Valachovic. "They must combat blazing downed trees, patches of increased winds and fire behavior, and other physical and logistical obstacles.”

Hugh Scanlon, chief of CAL FIRE's Alder Conservation Camp, helped co-author the recent paper with Valachovic and others. 

"In many cases, modeled wildfire conditions in sudden oak death affected forests exceed safety thresholds for handcrews, calling for changing suppression tactics and strategies," Scanlon says. "This can mean more heavy equipment, aircraft use, indirect lines and more area burned with higher intensity.”

Sudden oak death is still a relatively new disease in California, and the long-term ecological consequences of SOD infection and spread are largely unknown. However, this research shows that fuels are one of the major issues associated with the disease, and will require increased attention and management in coming years. For more information about this study, see the full paper, which was published in the journal Forest Ecology and Management (http://www.sciencedirect.com/science/article/pii/S0378112711001228.

To see a map showing the locations of sudden oak death in California, go to http://www.oakmapper.org/. At the website, you can also download the Oakmapper iPhone app to help UC scientists monitor the disease by reporting suspected cases of sudden oak death. 

Posted on Wednesday, February 15, 2012 at 6:56 AM
Tags: sudden oak death (4), wildfire (2)

Want to report SOD? We’ve got an app for that!

When the great outdoors is your research laboratory, gathering data can be a challenge. To get a broader perspective on the extent of damage caused by sudden oak death, a UC Berkeley Cooperative Extension geographer is using crowd sourcing to enhance her research on the disease that has killed over a million of California’s iconic oak trees since 1995.

Maggi Kelly, UC Berkeley Cooperative Extension specialist, started collecting data from community members through her OakMapper website in 2001. Now she has a mobile application for smartphones

.

While out in a park or forest, iPhone users can use the new OakMapper mobile app to report sightings of trees killed by Phytophthora ramorum, the plant pathogen that causes SOD. Onsite, participants can note the symptoms they see, such as seeping, bark discoloration, crown discoloration, dead leaves, shoot die-back, fungus, beetle frass and beetle bore holes.

The OakMapper app, created by scientists in the UC Berkeley Geospatial Innovation Facility, uses the phone's built-in GPS to identify the participant’s location when the data is submitted.

They also can describe the environmental setting, such as residential landscape or natural forest.

“Many of the challenging natural resource problems that we face today – like invasive species, fire, climate change – are large in spatial scale and impact diverse public groups,” said Kelly, director of the UC Berkeley Geospatial Innovation Facility. “Addressing these challenges often requires coordinated monitoring, efficient data collection, and increased communication and cooperation between scientists and citizens.

Science can benefit from your powers of observation. We all benefit by becoming informed about problems such as sudden oak death.

If you are like me, a person who sometimes doesn’t recognize coworkers outside the office, you may choose a spectator role. You can use the app to look at the maps to see where SOD is taking down trees.

For more information about OakMapper and its app, visit oakmapper.org. The OakMapper app can be downloaded for free from the iTunes app store.

I’ve heard of two other apps developed at UC to collect natural resources-related data from other scientists and interested members of the public.

You can use UCLA’s What’s Invasive apps to report locations of top invasive plants and animals, which compete with California’s native fauna and flora. By submitting location data and setting up top invasive lists for your area, you can assist scientists monitoring the spread of the destructive invasive plants and animals. Images and brief descriptions in the app help with identification. The apps are free and available for the Android and iPhone.

Soon you will be able to report roadkill sightings on your iPhone. The UC Davis Road Ecology Center has submitted to the iTunes store an iPhone app for reporting roadkill. Until the app becomes available sometime in January, you can report your observations to the California Roadkill Observation System via the Web at http://roadecology.ucdavis.edu/CROS.html.

Another cool app has been developed by the UC Davis Soil Resource Laboratory to deliver information to scientists, growers and gardeners about the properties of their soil. While standing in the field, the user can receive location-based information on a GPS-enabled cell phone. The app is available for free for iPhone and Android OS platforms.

Which science-related apps are you using? You can share them in the comments section or e-mail me at pskanrice@ucdavis.edu.

Posted on Wednesday, December 22, 2010 at 6:33 AM
Tags: apps (1), invasive species (1), Maggi Kelly (1), roadkill (1), soil (1), sudden oak death (4)
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