Research: climate change may reduce conifer regeneration after wildfire

regeneration after wildfire
A decade after a stand-replacement forest fire on the Metolius watershed in Central Oregon, almost no trees have begun to regenerate on one of the dry sites at lower elevation. (Photo courtesy of Oregon State University)

Government employees working for Oregon State University have determined that predicted increases in temperature and drought in the coming century may make it more difficult for conifers such as ponderosa pine to regenerate after major forest fires on dry, low-elevation sites, in some cases leading to conversion of forests to grass or shrub lands, a report suggests.

But even though you paid for it already by funding the research as a taxpayer, it will cost you $35.95 to purchase a copy of their findings, written by Erich Kyle Dodson and Heather Taylor Root of the University’s Department of Forest Ecosystems and Society in Corvallis, Oregon. The for-profit Elsevier corporation headquartered in the Netherlands published the paper. Wildfire Today supports open access to the results of taxpayer-funded scientific research. (UPDATE April 4, 2018: the research is now available for no additional charge.)

Dodson and Root concluded that moisture stress is a key limitation for conifer regeneration following stand-replacing wildfire, which will likely increase with climate change. This will make post-fire recovery on dry sites slow and uncertain. If forests are desired in these locations, more aggressive attempts at reforestation may be needed, they said.

The study, published in Forest Ecology and Management, was done in a portion of the Metolius River watershed in the eastern Cascade Range of Oregon, which prior to a 2002 fire was mostly ponderosa pine with some Douglas-fir and other tree species. The research area was not salvage-logged or replanted following the severe, stand-replacing fire.

“A decade after this fire, there was almost no tree regeneration at lower, drier sites,” said Erich Dodson, a researcher with the OSU Department of Forest Ecosystems and Society. “There was some regeneration at higher sites with more moisture. But at the low elevations, it will be a long time before a forest comes back, if it ever does.”

Similar situations may be found in many areas of the American West in coming decades, the researchers say, and recruitment of new forests may be delayed or prevented – even in climate conditions that might have been able to maintain an existing forest. While mature trees can use their roots to tap water deeper in the soil, competition with dense understory vegetation can make it difficult for seedlings to survive.

Openings in ponderosa pine forests created by wildfire have persisted for more than a century on harsh, south-facing slopes in Colorado, the researchers noted in their report. And fire severity is already increasing in many forests due to climate change – what is now thought of as a drought in some locations may be considered average by the end of the next century.

If trees do fail to regenerate, it could further reduce ecosystem carbon storage and amplify the greenhouse effect, the study said.

Restoration treatment including thinning and prescribed burning may help reduce fire severity and increase tree survival after wildfire, as well as provide a seed source for future trees, Dodson said. These dry sites with less resilience to stand-replacing fire should be priorities for treatment, if maintaining a forest is a management objective, the study concluded.

Higher-elevation, mixed conifer forests in less moisture-limited sites may be able to recover from stand-replacing wildfire without treatment, the researchers said.

Wildfire briefing, October 4, 2013

Measuring live fuel moisture from space

Southern California researchers at Chapman University and the Jet Propulsion Laboratory are trying to develop a model that would use data from satellites to determine the amount of moisture in live vegetation. This is an important variable that planners and fire behavior analysts need when managing preparedness and predicting the spread of wildfires. The NASA funded work is in the preliminary stage. If the effort is successful it would be possible to obtain daily updates of live fuel moisture using information collected by two satellites, Terra and Aqua, the first passing overhead in the morning and the second in the afternoon.

When I was Captain at Descanso Station in southern California it was an official fuel moisture monitoring location. Every 10 to 14 days our engine crew would drive out on Viejas Grade Road and fill one-quart paint cans with clippings from chamise bushes. This is still being done all over the western United States, but with different species in other areas. In the basement back at the station we would weigh the unopened cans, then after removing the lids the cans would be placed in a convection oven overnight at moderate heat, and weighed again the next day. The entire building had the smell of cooked chamise. After accounting for the weight of the empty can, we would calculate the percent moisture that was lost. I plotted the data on a graph on a piece of paper along with the readings from the previous year, then made copies and snail-mailed them to the other fire stations on the District. Obviously this was before everyone had a computer on their desk and in their pocket.

Research: red stage needles do not recover moisture overnight

Preliminary research indicates that red stage lodgepole pine needles do not recover fuel moisture overnight, as occurs in other fine, dead surface fuels. The study was conducted on foliage from trees that had been attacked by mountain pine beetles. If this is confirmed it will have implications for predicting the rate of spread of fires in bug-killed stands.

Time Magazine: firefighting tactics in a warming world

Bryan Walsh, a senior editor at Time, writes about the increasing number of fires and considers a less than aggressive suppression strategy for some of them. In the article he used a phrase we have written many times:

The U.S. fights wildfires like it once fought wars—with overwhelming force aiming for unconditional surrender.

We do not entirely agree with Mr. Walsh. The federal land management agencies at one time DID fight fires with the overwhelming force they could muster, but budget cuts, a leadership vacuum, and timid initial attack policies have made that a distant memory. However some organizations still do have overwhelming force strategies, such as CAL FIRE.

Another “wildfire”

We take notice when the word “wildfire” is stolen and attached to something that has no connection to a fire that burns vegetation. There have been Wildfire songs before, but The Saturdays recorded a new version this summer.

Researchers studying the effects of wildfire smoke on cloud formation

Researchers from the Department of Energy’s Brookhaven National Laboratory and Pacific Northwest National Laboratory are flying over fires this summer in the Pacific Northwest and Tennessee to study how particles called aerosols given off by wildfires and agricultural burns evolve over time. The Biomass Burning Observation Project will gather data to help researchers flesh out one of the least understood areas of climate, the role of aerosols in cloud formation and climate.

Recently the researchers have sampled smoke generated by the Milemarker 28 and Colockum Tarps Fires in Washington, and the Elk and Pony Complexes in Idaho.

Research: wildland fire smoke, including tar balls, contribute to climate change more than previously thought

Manvendra Dubey
Manvendra Dubey

As soon as they were able to repopulate the facility after being evacuated due to the huge Las Conchas Fire in 2011, scientists at the Los Alamos National Laboratory in northern New Mexico set up an extensive aerosol sampling system to monitor the smoke from the smoldering fire for more than 10 days.  The team used field-emission scanning electron microscopy and energy dispersive X ray spectroscopy to analyze the aerosol samples and determined that spherical carbonaceous particles they called “tar balls” were 10 times more abundant than soot. The Los Alamos scientists were the first to discover tar balls and coated soot.

Senior laboratory scientist Manvedra Dubey noted that, “Most climate assessment models treat fire emissions as a mixture of pure soot and organic carbon aerosols that offset the respective warming and cooling effects of one another on climate. However Las Conchas results show that tar balls exceed soot by a factor of 10 and the soot gets coated by organics in fire emissions, each resulting in more of a warming effect than is currently assumed.” He said this should have a huge impact on how the aerosols are treated in computer models.

These photos of soot particles from the Las Conchas Fire are from a paper written by Mr. Debey and the three other scientists from Los Alamos National Laboratory listed below.

Bare soot particle
Bare soot particle. Los Alamos National Laboratory image.
Embedded soot particle
Embedded soot particle. Los Alamos National Laboratory image.

Mr. Dubey, along with postdoctoral fellow Allison Aiken and post-bachelor’s student Kyle Gorkowski, coordinated with Michigan Tech professor Claudio Mazzoleni (a former Los Alamos Director’s fellow) and graduate student Swarup China to perform the study.

This week on Twitter Mr. Dubey solicited and then answered questions about his fire smoke research:

Lab Chat Q&A Summary

Continue reading “Research: wildland fire smoke, including tar balls, contribute to climate change more than previously thought”

Studying pyrocumulus

Pyrocumulus on the Jasper Fire
Pyrocumulus on the Jasper Fire, August 25, 2000. Photo by Bill Gabbert

You may be familiar with pyrocumulus (pyroCb) clouds that form over intensely burning vegetation fires. They can be a combination of smoke and condensation. Some firefighters call this “ice capping”.

Chuck Bushey, a Fire Behavior Analyst and former President of the International Association of Wildland Fire, is a member of a small group studying pyroCb led by Mike Fromm of the US Naval Observatory.

Chuck sent me a link to an animation of pyroCb forming over the Silver Fire recently in southern New Mexico, and explained:

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“…this is one recent example of the sort of products our small global pryoCb group watch. The group also examines lots of particulate and atmospheric information (some from ground based instrumentation such as Lidar, as well as from other satellite channels) to make sure it’s a real fire event or something else. There are other events that may look similar from orbit and some of the more remote incidents that this group sees we may be the first observers.

We can sometimes track these major upper atmospheric (stratospheric) events multiple times around the globe mixing with other weather systems. The most global round-trips I have observed has been four in the northern hemisphere.

We can only speculate on what the input of the volatile elemental and organic chemicals and other pyrolyized materials (such as soil and ash) are having on the cold, upper atmosphere and our climate. We also guess that these events may be more frequent now and maybe more intense than in the recent past but we really don’t know because no one was watching and our capabilities were limited.”

Effectiveness of fuel reduction treatments

Wallow fire, two burn areasA report has been released that had the objective of determining if fuel reduction treatments are effective in reducing the severity and cost of wildland fires. It was prepared for the U.S. Department of Interior’s Office of Wildland Fire by the Ecological Restoration Institute at Northern Arizona University. The reason it was written is interesting, according to the report: (emphasis added)

The Office of Management and Budget, Government Accountability Office and the United States Congress have repeatedly asked the Office of Wildland Fire in the Department of Interior and the United States Forest Service to critically examine and demonstrate the role and effectiveness of fuel reduction treatments for addressing the increasing severity and cost of wildland fire. Federal budget analysts want to know if and when investments in fuel reduction treatments will reduce federal wildland fire suppression costs, decrease fire risk to communities, and avert resource damage.

The report has a catchy title: The efficacy of hazardous fuel treatments: A rapid assessment of the economic and ecologic consequences of alternative hazardous fuel treatments: A summary document for policy makers.

Here are a few of the conclusions reached by the 12 authors and researchers:

  • Studies that use the avoided cost approach to examine the cost of fire demonstrate that treatments result in suppression cost savings.
  • Modeling studies that evaluate the effectiveness of fuels treatments in terms of changes in wildland fire size, burn probabilities, and fire behavior demonstrate that fuel treatments applied at the proper scale can influence the risk, size, and behavior of fire therefore reducing suppression cost.
  • Modeling demonstrates that fuel reduction treatments are effective at reducing fire behavior (severity) where implemented, and can successfully reduce fire risk to communities.
  • Although few studies exist on the topic, fuel reduction treatments significantly enhance the price of adjacent real estate, whereas homes in close proximity to a wildfire experience lower property values.