This year’s wildfire season just passed the ninemillion-acre mark, making it among the top four most expansive fire seasons in the U.S. since accurate monitoring began in the ’60s. These wildfires are as destructive and dangerous as they are inevitable. Drought conditions, which many regions of the country are dealing with right now, only compound the problem, making fires more likely and more severe.
As disastrous as this is, it’s only the beginning of the potential dangers, especially with such lively winter weather in the works. Wild storms, of the type that El Niño can summon, regularly cause mudslides and flooding in Southern California. Should these storms reach charred land without proper protection measures in place, they won’t just refill the reservoirs, they’ll strip the landscape bare.
Once the greenery has been burned away, the topsoil becomes vulnerable to the forces of erosion. With nothing left to keep the soil in place, it can easily move down denuded slopes and enter stream channels. The result is polluted water and destroyed habitats.
A healthy forest can keep soil in place. Tree and plant roots stabilize the soil, while the thick layer of underbrush keeps it from being carried off. But when wildfires destroy this coverage, it falls on human beings to step up and prevent further destruction, as well as help revive the woodland. That’s where we come in.
Fire-damaged areas will eventually mend themselves. But we can’t wait for nature if we want to prevent erosion; we need to jumpstart the recovery.
We tend to forget that wildfire is a natural part of the forest lifecycle, clearing away overgrowth and germinating new seeds. Areas of light-to-moderate burn severity have the ability to renew on their own, so seeding perennial species in these areas is not normally necessary.
There are many seeds dormant in the ground, waiting for the right conditions to germinate. However, that tender new growth will need protection. A temporary ground cover can help.
But let’s back up a bit. Before any seeding is done, the scorched soil should be analyzed. In severe, slow moving fires, the combustion of vegetative materials creates a gas that penetrates the soil profile. This gas covers the soil and causes it to repel water. This phenomena is called hydrophobicity. Some amendments, such as humic acid, will probably be needed so the seeds can ‘take’. Several soil conditioners contain humic acid, along with other nutrients.
“We work with a humic acid conditioner that penetrates the soil and helps neutralize that hydrophobic barrier,” said Darren Klotz, a sales professional for Rocky Mountain Bio-Products in Denver, Colorado. “It would be applied either through a hydroseeder or a broadcaster, depending on the slope.”
Another important element regarding reclamation efforts in remote places is accessibility. There could be roads blocked by downed trees. You’ll need to assess this before you start. Can you drive a spray truck to the site, or will you have to work from the air?
“Depending on the area you’re in, your method could differ—from broadcast seeding to drill seeding— though drill seeding is generally the preferred method,” says Scott Lambert, a native plant specialist for Rainer Seeds, Davenport, Washington. “Wildfires can cover such large areas that sometimes aerial seeding has to be done, either from fixed-wing planes or helicopters.”
“If it’s possible, following aerial seeding, I’ll sometimes use a harrow to get the seed incorporated into the soil,” Lambert added.
Now we come to the choice of seed. The ideal seed to use will depend on the region, climate and soil type that you’re dealing with. Whenever possible, go with native plant material. That way, you’re putting down what Mother Nature had there to begin with. However, if you need quick establishment, you may want to go with something that’s fast-growing. Whatever seed you decide to work with, make sure that it’s certified seed of a wellknown variety.
“One of the big challenges with reseeding is the variance in the size of seeds,” says Lambert. “For instance, sage seed contains about 2.5 million seeds per pound, whereas some wheat grass seeds might have 100,000 seeds per pound.”
Size also makes a difference in deciding how seeds should be placed in the soil. “Smaller seeds should generally be buried shallower, while larger seeds can be put down deeper.”
After the sowing has been completed, additional steps should be taken to ensure that the seeded area germinates and grows. Almost all plant life requires some degree of care in order to stay healthy, and the site that you’re repairing is no different. If the budget permits, putting down a layer of straw mulch as a protective covering is a good idea. This will help keep the seed in place and hold in moisture.
The screen of straw should not only cover the reclamation area, but extend to areas that haven’t been damaged. It’ll help stop wind and water erosion.
“Mulching does carry some risks,” says Lambert. “If you do too little, it’s not going to help, and if you do too much, it will stifle the new plants. It can be useful, though, if you can get it anchored in.”
“Anchoring it in” is especially called for if you’re working in a wide-open area. A strong breeze could come along and make all your efforts “gone with the wind.” To keep your straw in place, use a crimper and some tackifier.
Hydroseeding is a great method for revegetating after a wildfire. Instead of amending, then seeding, then mulching, then watering, you do it all at the same time. Water, seed, fertilizer and mulch are mixed together and sprayed on the denuded region, providing speedy, effective, and even distribution on a site. Hydroseeding is an especially efficient way to reseed slopes.
“Hydroseeding stabilizes burned areas by holding down the fine soil and ash on the surface to keep it from moving, either due to wind or water,” says Ron Dietz, president of Dietz Hydroseeding in Sylmar, California. “The important thing in post-fire hydroseeding is to protect drains, homes and other structures from the dust and the mudslides that occur with rains when there’s no plant cover.”
Being wary of weeds
However, the work doesn’t stop just because the sowing is finished. There are still steps that ought to be taken so that no further environmental damage occurs; the first should address weeds.
When forest life begins to come back, weeds are among the first plants to recolonize. If any of those weeds are classified as noxious or invasive, then steps to control them should be taken right away.
“If you’re bringing in soil or compost, there’s a chance of invasive weeds coming in along with it,” says Klotz. “If you’re using existing soil, there might also be a ‘weed seed bake’ waiting to happen. When you start to reseed, they will like the new situation just as much as your new seeds. The standard management practice is to let them grow to a certain point, and then try to keep them mowed down before they can go to seed.”
The best way to
control these pests is by using integrated pest management techniques,
natural methods that avoid chemicals. These methods will allow you to
control the weed population without damaging the new vegetation that’s
been planted. Your ability to do this, however, will be affected by your
location, the budget, and what’s specified by your work contract.
Further erosion control measures
Reseeding is the main thing that will help the land recover and stay in place. However, there are additional control devices that can be deployed to help mitigate further soil erosion and sedimentation of water habitats in a reclamation area.
Conventional erosion control tools, such as silt fences and straw wattles, can come in very handy at wildfire reclamation sites, too. Use silt fencing to hold back sediment on flat areas, while straw wattles will provide good control on slopes.
“Because we’re up here in the Rocky Mountains, on the slopes, even an inch of rainwater will carry soil away, cause flooding or other problems downstream,” says Klotz. “So erosion control is a serious concern for us.”
You can protect slopes by using tools left behind by the wildfire itself. After a blaze, some trees will be so badly burnt that they’ll have to be cut down before they fall down. Use these charred tree carcasses to create log terraces.
They’re great for channeling runoff water down inclines.
When setting up a log terrace, start at the top of the grade and work down, so you can visualize the water flow. Lay the logs lengthwise, across the slope, in an alternating fashion, so that runoff can’t travel straight down. The idea is to force the water to zig and zag through the log course, slowing it down, giving it time to percolate into the ground. The logs should be embedded in the soil and backfilled, so that water can’t run underneath. Drive stakes in on the downhill side to keep them from rolling away.
A straw bale dam can also be built, by placing bales in rows with the ends overlapping. As the water flows through the bales, the sediment will be caught by the straw fibers. Excavation and staking will keep the bales in place. Put straw bale dams at the ends of your log terraces.
No two forests are exactly alike, and neither are the fires that destroy them. The methods you’ll employ to control erosion in the aftermath will depend on the information you can glean before you get there, and what you’ll find when you finally set eyes on it. You’ll have to decide what tools and techniques your experience tells you will work best in each individual circumstance.
Doing wildfire reclamation is a tough, challenging assignment, but a very rewarding one. It’s also an important job, because the alternative is chaos. Mudslides, sediment flows and other erosion that follow in the wake of wildfires cause further damage to people, property and the environment. By doing the job effectively—and quickly—you not only prevent erosion, you help bring a forest back to life.
Not bad for a day’s work.