Once a raging forest fire is quelled, the next worry is erosion of the landscape. With vegetation destroyed, rain easily washes away the soil, causing large flows of debris and landslides. Erosion endangers sources of drinking water, streams, and roads.
In an unprecedented study, Chris Pannkuk and Peter Robichaud show that scorched evergreen needles can play a key role in preventing erosion after a forest fire. They found that ponderosa pine needles were effective in reducing erosion caused by water running over the soil, and Douglas fir needles were effective in reducing erosion caused by rain hitting and splashing into soil. Their report will appear in Water Resources Research, published by the American Geophysical Union.
These findings can help post-fire rehabilitation teams decide where to apply treatments to reduce erosion. "If you see brown needles in the trees," Robichaud said, "then lets take advantage of Mother Nature and not add any treatments to that area of the forest."
Wildfires usually burn in mosaics, with patches of low, moderate, and high severity. In areas of low or moderate severity, needles from partially burned conifer trees fall to the ground within a few months after the fire. Robichaud noticed that needle cover seemed to reduce erosion on forest soils after a fire. Since no one had formally studied this effect, he and Pannkuk used an artificial rain laboratory at the U.S. Department of Agricultures Forestry Science Laboratory in Moscow, Idaho, to see how much burnt needles could reduce erosion.
They filled four-meter by one-meter [13-foot by 3-foot] boxes, set at a 22-degree slope, with soil taken from burnt forests. After covering the soil with various amounts of scorched ponderosa pine and Douglas fir needles, they applied artificial rain for 25 minutes at an intensity that would simulate 34 millimeters [1.3 inches] of rain per hour. During each test, they also introduced a stream of water at the top of the box to simulate overland water flow.
The researchers collected and analyzed run-off soil and water from the boxes. They found that a 50 percent ground cover of Douglas fir needles reduced water flow erosion by 20 percent and rain-induced erosion by 80 percent. A 50 percent ground cover of ponderosa pine needles reduced water flow erosion by 40 percent and rain-induced erosion by 60 percent.
Robichaud, who has been studying and modeling erosion after prescribed and wildfire for 13 years, directs several treatment effectiveness projects in California, Colorado, Idaho, Montana, Nevada, and Washington. Pannkuk, who worked with Robichaud as a post-doctorate on this project, is currently a natural resources consultant.
Harvey Leifert | AGU
Robotic weeders: to a farm near you?
10.01.2018 | American Society of Agronomy
Alfalfa loss? Annual ryegrass is a win
03.01.2018 | American Society of Agronomy
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
16.01.2018 | Materials Sciences
16.01.2018 | Materials Sciences
16.01.2018 | Power and Electrical Engineering