Tue June 10, 2008
Earth Notes - After the Fire I
Flagstaff, AZ – Earth Notes: After the Fire Part I
Forest fires blaze across the Southwest's headlines every year. They're dramatic and dangerous. Ecologically, though, conditions on the ground after a fire are often more important than what happens while the flames flicker. Throughout the next month, Earth Notes will look at what happens . . . after the fire.
For land managers, one of the biggest potential headaches after a fire is soil erosion. Fires, after all, bare the ground. Some leave behind charred soils that are hydrophobic, or impermeable to water. When the soil's structure breaks down, moisture can't sink in, and organic matter and nutrients are lost.
With the first intense rainstorm after a fire, slurries of ash and sediment pour into streams, clouding the water and choking aquatic life. In 2002, black runoff from Arizona's huge Rodeo-Chediski Fire churned into Lake Roosevelt, threatening fish.
To rehabilitate the land, time-tested erosion-control measures are used. Dead trees are set across slopes to create erosion barriers. Check dams of wood or stone are built across channels, and contour trenches are dug to redirect water.
Grasses and ground covers are planted, though their seeds can wash away in heavy rains. Rolls of straw are set perpendicular to slopes to serve as mulch. Wet mulches can be sprayed on too, but they can be costly.
Sometimes, though, the best rehabilitation practice is to leave a place alone so that nature herself can begin the healing process. Next week, we'll look at a bird that likes severely burned areas just fine.