From fire to ferns: Forest is expected to thrive
July 30, 2008
Five weeks after the Yuba River Complex fires began in Nevada County, ferns are sprouting from the scorched earth.
But as the forest takes an estimated three years to return to its pre-fire productivity, dead trees, a marred landscape and ash in the water are some of the negative consequences of the fires.
Before the fires were contained, forest hydrologists Tim Biddinger and Rick Weaver were studying the soil as part of their Burned Area Emergency Response (BAER) for the Tahoe National Forest.
The team is studying what emergency measures need to be taken to protect water quality, life and property and minimize erosion and downstream flooding before the first winter storms hit.
“We’re looking at the watershed as a whole,” Weaver said.
Foresters are in the process of looking at long-term restoration work, such as harvesting burned forests or seeding burned areas. A full environmental review is required and will take time, said forest spokeswoman Ann Westling.
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Started by dry lightning on June 21, fires burned 4,235 acres within the Yuba River watershed before they were contained.
On the American River, another 20,541 acres burned; the Government Springs/ Westville Fire along the North Fork was fully contained on Wednesday.
After flying over burned ridgetops, collecting data from satellite images and testing the water retention of soil dug from pits in burned forests, Biddinger and Weaver examined how severely the fires affected soil, plants and waterways. They summarized their findings in a national Burned Area Report. Within the report, the team classified soil burn severity into three categories, based on the fires’ effects on the environment.
They look at the soil impacts by studying how severely the trees are burned. If trees have enough dry needles and leaves remaining after the fire, that material will fall and protect the soil from the elements by decomposing into the topsoil.
They found 77 percent of soil and vegetation burned in the low soil burn severity category.
Another 18 percent of the burn was classified as moderate, meaning the fires scorched the trees and killed them, but left the needles and leaves attached.
Another 5 percent of the burned area was in the high soil burn severity category, leaving nothing but blackened sticks.
“It could have been a lot worse,” said Biddinger.
Foresters want to see fires burn at lower temperatures to remove unwanted brush, ground cover and lower limbs without harming the trees.
“It mimics a prescribed fire. This is about what we try to do when we prescribe a burn. (It’s) beneficial to the forest,” Biddinger said.
“It’s just good for the soil. That’s why we don’t differentiate if (the trees) are dead or not. We just want to know how many needles are retained,” Weaver added.
Unlike other forest lands in California, the Tahoe National Forest does not have a “let it burn” policy because of a checkerboard pattern of private ownership – up to 45 percent – within its boundaries. Protecting utilities, water sources, resorts, campgrounds, houses, recreational lakes and timber lands are a priority.
“One of the things about this area is we can’t let it burn. These are commercial timber lands. We have to stop it before it gets there,” Weaver said.
Pacific Gas and Electric Co. and Sierra Pacific Industries already have begun harvesting burned timber from their private holdings within areas of the Fall Fire.
The South Yuba River’s water quality may be clouded shortly after the first few rain storms this winter, Weaver said. Luckily, fires burned low and moderate in the Canyon Creek drainage, the water source for the town of Washington.
“You’re probably going to see some ashy water, which will quickly wash through the system,” Weaver said.
Life returns to even the harshest moonscapes created by fire.
It usually takes about three years for a blackened wasteland to reach a point where the soil has returned to its previous productivity, Weaver said. Gophers, worms and rodents speed up the process.
Already, green sprouts have appeared from oak stumps killed in the American River Complex fires, the U.S. Forest Service’s Rick Weaver said.
“It could be completely burned down to a nub, and it will sprout,” said USFS Forester Tim Biddinger. Manzanita, ceanothus and oak are especially adapted to fire.
Next spring, young green grasses unobstructed by brush will attract deer and quail and the predators that feed on them.
“After a fire comes through, it means more habitat for animals in the long term. Some animals really thrive after a fire,” Weaver said.