Working With Nature Following Wildfire

Advice from the field

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Inappropriate plastic sheeting slope protection. Even if this were a situation that would benefit from emergency plastic covering, it wasn’t installed correctly.
When you control water, you control nature. So why not use nature in your erosion and sediment control efforts? Many (if not all) erosion and sediment control practices attempt to control raindrops or runoff in one form or another, especially those that are applied to landscapes following wildfire. If you are not fully aware of the natural processes in play following fire (or what I like to refer to as “the nature connection”), then your erosion and sediment control efforts may fall short or even be self-defeating.

I spent five months assisting property owners impacted by the devastating 2017 wine country wildfires in northern California and then the Thomas Fire in southern California. The Thomas Fire became the largest wildfire in California history, having burned 281,893 acres and destroying 1,063 structures, most of them homes in Santa Barbara and Ventura ­Counties. I also met with homeowners in ­Montecito whose properties were damaged or destroyed by debris flows. I conducted post-fire/debris flow site assessments on more than 150 properties and gave presentations on post-fire restoration at several community meetings, where I was able to reach several hundred more fire victims.

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A hydromulched depression where a house once stood. The purpose of the practice is to contain any toxics and protect soil on the house lot, but in this case the practice will only have minimal effects because there is no opportunity for this depression to produce damaging runoff from the site. Straw wattles were placed on top of, but not “keyed into,” the soil. Having been applied to the top of the slope depression, they would come into play only in the unlikely event of direct rainfall completely filling the depression and causing overflow.

I retired last year after a 43-year career with the USDA Natural Resources Conservation Service (NRCS) as a field district conservationist in Santa Cruz County, CA. I have assisted countless landowners, including those impacted by wildfires all over California, since 1974. NRCS hired me back in October 2017 as a contractor to assist individuals with their post-fire damage needs as a post-fire restoration specialist and erosion and sediment control specialist.

With each fire I learn more, and these fires were no different. I advised property owners and contractors not only on the proper use of erosion and sediment control measures following fire but also on how not to respond and to let nature do her magic. Three of my most popular talking points are

  • every site is unique;
  • one size does not fit all;
  • work with nature.

Many property owners can’t afford to cover their properties with expensive erosion control blankets, hydromulch, jute netting, or other products. They need information on other softer and less expensive approaches to restoration following fire and, in some cases, to know that doing nothing at all can sometimes be the best thing you can do.

Join us in Atlanta August 18–22, 2019  for StormCon, a five-day special event to learn from experts in various water-related arenas.  Share ideas with peers in your field and across industries—exploring new stormwater management practices and technologies.  Click here for details

I saw situations where unnecessary measures were being installed in and around the burn areas, as well as situations where the erosion or sediment control product was not being located or installed properly. I would not be going out on a limb by stating that more than half of all fiber rolls and straw wattles that I saw placed in fire damage areas were either not needed, improperly installed or located, or, in some cases, potentially creating a problem rather than preventing one.

Other post-fire erosion control practices I saw installed or applied improperly included jute netting, erosion control blankets, seeding, mulching, sandbags, straw bales, water bars, drainage ditches, land grading, vegetation removal, and, to a lesser degree, hydromulching. In most cases, hydromulching was done correctly, but it just wasn’t needed in many of the situations or was overkill, especially when seed was added in applications done in January.

Additionally, plastic sheeting was being specified and installed by homeowners and their workers on slopes without regard to plant materials, increased runoff from plastic, or other detrimental effects that plastic presents to slopes. In fact, plastic sheeting should be used only according to a site-specific design prepared by a licensed and certified expert. In the majority of cases, plastic sheeting (especially non-transparent plastic) makes the situation worse and can cause other problems by killing slope-holding plant root systems and soil microorganisms, preventing seed and plant regeneration, increasing runoff, and maintaining slope-saturated conditions when covering wet slopes with plastic instead of allowing the soil to dry out.

Even straw mulching wasn’t being done properly. In many cases, it was being spread too deep or where it was not needed, such as under trees where there was a heavy leaf drop from trees suffering only from heat and smoke damage. Straw depths greater than 2 to 3 inches can delay native regeneration of plants and suppress the resident grass and forb seed bank in the soil.

Jute netting was applied across the slope in several situations and almost always without mulch underneath. Netting had inadequate overlap and way too few staples or was covered with sandbags instead. It was also applied “tented” over cut burned plant materials and not in complete contact with the soil. In several locations, I observed straw wattles installed on top of the jute netting with no soil contact and with too few stakes.

As mentioned earlier, straw wattles were incorrectly installed or poorly located, probably more than any other measure that I saw. Water bars that collect and redirect surface runoff on unpaved access roads and fuel breaks were a close second.

I was so concerned by what I saw that it made me want to write this article. I kept thinking that if fire victims are going to spend the time, money, and effort to install restoration practices, then why not do it right? I quickly came to the conclusion after speaking to property owners and their hired help that they honestly did not know that they were doing anything wrong. Clearly, there is a need for more and better erosion and sediment control education, especially for those that will actually be performing the installations of erosion and sediment control practices.

This jute netting and plastic covering give the
homeowner a false sense of security and actually
make the situation worse.

Installing measures such as erosion control blankets, straw wattles, and jute netting and removing fire-damaged vegetation can cause disturbances to the soil, slopes, plant root systems, resident seed bank, and any natural plant regeneration taking place. These factors need to be kept in mind before deciding to make the disturbances. In some cases, the disturbances are necessary to provide a higher level of protection, but not always. In other cases, less is more—and nothing at all may be best.

It appeared to me that many of the erosion and sediment control practices in the fire areas were being applied as if one size fits all and without much consideration of site-specific variables, including natural restoration processes in effect. These variables include burn intensity; topography; soil type and geology; and preexisting conditions such as plant type and wildlife habitat (including threatened or endangered species), disturbances made by the fire-fighting effort, surrounding land uses, and drainage and runoff patterns.

Some of nature’s handiwork following wildfire includes

  • regeneration of plant materials from the remaining plant or from its root system;
  • leaf drop from trees receiving minor damage including heat or smoke damage, which provides natural mulch on soil and slopes;
  • ash from burned plant materials, which provides an absorbing and protective layer on the soil from first rainfall following fire;
  • soil hydrophobicity effects, which can help reduce slope saturation where deep-seated instability may be an issue;
  • germination of “fire plants” such as grasses, forbs, and other plants from the resident seed bank in the soil that have lain dormant for decades just waiting for wildfire to sprout;
  • burned plant materials, which provide some degree of canopy (whether still standing or lying on the ground), dissipating the speed of raindrops traveling 30 miles per hour before those drops hit bare soil, thus preventing or slowing runoff;
  • preexisting plant root systems in the soil, which have a soil- and slope-holding ability even if the entire plant above the ground was completely vaporized—any disturbance to these root systems will delay the regeneration process and could cause an increase in soil erosion rates;
  • other site-specific factors.
Straw wattles and jute netting incorrectly installed. Staking is inadequate and the wattles are “riding” on top of netting. Jute net is
“tenting” over cut vegetation with too few staples and sandbags to help hold it in place. Note the upper slope covered with plastic on
the neighboring property in the background.

It is absolutely critical to consider nature’s role in post-fire restoration before jumping the gun and throwing everything but the kitchen sink at the fire-damaged landscape. Please don’t get me wrong: I believe there is a definite and necessary place for erosion and sediment control product installations in the post-fire landscape. I just want to make sure before making recommendations and doing the work on the landscape that nature’s role is considered in any and all treatment solutions.

I developed several handouts during the time I spent assisting property owners in all the fire areas so that they would have some written information and guidance at their fingertips before making any disturbances to their fire-damaged lands or before they hired anyone for help. I boiled down my top 10 talking points from those handouts. They are as follows:

#10—Get help from NRCS and/or other professionals that are certified, registered, and/or licensed before selecting and installing treatment measures.

#9—Respect the laws of nature. Natural recovery can be quicker, with longer-term benefits, when you design with nature. Remember, when you control water (runoff) you control nature—which can have disastrous consequences.

#8—One size does not fit all. Every property has unique features and circumstances requiring a site-specific evaluation and corresponding treatment. This is one more reason not to do what your neighbor is doing—and besides, they might not know what they are doing.

#7—Minimize soil and slope disturbances. Ash, leaf drop, downed trees, and remnant burned vegetation all play a role in protecting the soil and slopes following wildfire.

#6—Look beyond your property lines and work with thy neighbor. Runoff, erosion, and debris flows have no respect for property boundaries.

#5—Prevent access roads from going to ruin. Roads will require more maintenance in the first few winters following wildfire. Many road drainage facilities may need to be replaced, relocated, and/or resized depending on the nature of fire damage to the surrounding landscape and watershed. Culvert inlet and outlet controls will be critical.

#4—Emergency and temporary measures typically have a high risk of failure. They can cause more serious problems if and when they fail and often provide a false sense of security.

#3—Remember the M&Ms. All existing and any planned treatment measures require regular and perhaps constant monitoring and maintenance, especially throughout the first two winters following wildfire.

#2—Say “No” to Yes. Sometimes doing nothing or doing less is best. Give nature a chance to do her job.

#1—There is NO silver bullet. When it’s not safe, it’s not safe. Have an emergency plan and get out of your home and leave your property when it’s not safe. EC_bug_web

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