A three-year study of defensible space and erosion control conducted by a group of local organizations found that tilling aged wood chips into the soil is most effective at minimizing fire risk and preventing erosion.
According to a press release from Integrated Environmental Restoration Services Inc., the study aimed to find common ground between landscape treatments effective at preventing erosing and minimizing fire risk. The study tested different practices and materials such as pine needles, aged duff, woodchips, composted woodchips, landscape bark, and duff and wood chips tilled into the soil. To find out which treatments prevented run-off, the different materials were exposed to a simulated rainstorm. To test for fire risk, materials were lit on fire using a drip torch administered by local firefighters and measured for flame height, rate of flame spread and burn temperature of the different materials, IERS stated.
Of all the treatments tested, the study found that mixing 1 to 3 inches of wood chips into soil to a depth of 4 to 6 inches promotes water infiltration and was the most effective at minimizing fire risk and preventing erosion.
"Mixing organic material, like wood chips, into the soil helps turn your soil back into a sponge," stated Kevin Drake, senior planner at IERS. "Instead of water running off your property, the loosened soil actually absorbs water."
No organic mulch is entirely fire resistant, which means planter beds with tilled in woodchips should be used along with rock, patios, or grass in a patchwork manner throughout landscapes in a patchwork manner. It is also important to create a non-combustible zone in the five feet directly around a home by applying gravel, rocks, or low growing non-woody plants like clover or native grass.
The study was conducted by Integrated Environmental Restoration Services Inc. in collaboration with Tahoe Resource Conservation District, Meeks Bay Fire Protection District, North Tahoe Fire District, and Homewood Mountain Resort.