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
Algorithm could streamline harvesting of hand-picked crops
13.03.2018 | University of Illinois College of Engineering
A global conflict: agricultural production vs. biodiversity
06.03.2018 | Georg-August-Universität Göttingen
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences