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The Purpose, Creation and Burning of a Slash Pile

Each year, the US Forest Service does a number of “controlled burns” in our area. More often than not, that is the burning of slash. Slash is just a general name for forest debris.

Each time trees are harvested in the forest, there are a lot of branches, needles (it is mostly pine, fir, and larch forests around here and all of these have needles rather than leaves), bark, and so forth, that is left behind. 

Further, when there is a forest fire, the trees aren’t burned to the ground in a pile of ash. Many of the trees are left dead but still standing. Many of the trees are dead even without any of the wood being singed. In any event, these trees must be sawed down. Occasionally, even pockets of living trees are often cut down.

In both cases, the debris must be moved and destroyed, in order for the Forest Service to replant the forest. This is often done with the use of bulldozers that push the debris into large slash piles or log decks. 

Slash piles are unsightly and they cover a fairly large area with forest garbage. Because of this, the piles are usually burned. Since the forest service does the burning, these are controlled burns. 

A couple of years ago, we had a major forest fire near town. Many trees were killed and the cleanup resulted in a huge slash pile bordering a forest service road about five miles from my home. The slash is piled about 20 feet deep, 40 feet wide, and it borders about 10-15 miles of the forest service roads. Once it is all seasoned, it will be burned and once it is burned, the forest service will replant the area with small trees.

All of this serves a purpose, though part of it is wasteful. I thought it might be worthwhile to explain what a slash pile was, how they are created, why they are created, and why they are burned.

  • Did you know the what, how, and why of forest slash piles before reading this?

    • Yes
    • No
    • I knew some of it


What do you think?

14 Points

Written by Rex Trulove


    • I’m glad that you do. Yes, the potassium is important and it also tends to counter the acidity caused by the accumulation of fir, pine, and larch needles. Forest fires, for all their destructive potential, are replenishing for the forests and do a lot of good. The burning of slash also does a lot of good, though it is inconvenient and sometimes even dangerous for the people that end up having to breathe the smoke.

        • I respect them rather than fearing them. They can be tremendously destructive and dangerous and they can move with incredible speed. However, they are also natural and do a great deal of good, sometimes in ways that can surprise people. We simply try to make sure that we have an emergency plan and supplies ready to go at a moment’s notice during fire season.

        • In the west, easily 75% of our forest fires are set by nature, primarily lightning. I don’t count California in that, simply because there are so many people and the bad fires last year were mostly because of improper forest management…allowing trees to have branches too close to powerlines, making arcing not only possible but likely.

          • in the east, there are few natural fires and more human fires. You do still have a fair number of net new fires in the west.

            If nature plans 3.
            but because of humans, there are 4, the ecosystem is built for that.

        • There are people who are careless and who don’t care, even here, but there are strong disincentives. If a person causes a forest fire, they go to great lengths to catch the person responsible and usually succeed. That person is then given the bill for fighting the fire and the damage done to the forests. Since that usually runs into the millions of dollars, they end up paying for the rest of their lives.

          They can also be sentenced for such things as negligence, recklessly endangering, destruction of property, and even homicide if anyone dies because of the fire. At best, they spend their lives paying monetary damages. At worst, they face a lot of time behind bars. Very few make the same mistake twice.

          Even the fine for leaving a smoldering campfire in a regulated campground and in a standard fire pit is quite severe. Forest Service personnel are also sticklers for checking to make sure the campers in every campsite has a shovel, bucket, and axe.

    • There is no doubt that the Amazon produces a lot of oxygen and locks up a lot of carbon. However, the same is true of the oceans and the arctic tundra. I don’t personally agree with the burning of Amazonian forests to make way for agriculture, but a lack of oxygen isn’t the biggest concern.

    • This is definitely nothing new. Large portions of forests have burned in the past and will do so in the future. In the case of the Amazon, most of that is intentionally set fires rather than wildfires. It is the wildfires that slash burning is designed to prevent.

      In 1871, there was an enormous fire in the city of Chicago that has come to be known as the Great Chicago Fire. It was enormously destructive and killed a lot of people. Many people were very aware of that fire, but what many people aren’t aware of is that at the time Chicago was burning, hundreds of thousands of acres of forests were also on fire in the northern US. The press stories were focused on Chicago, so fewer people even heard of the tremendous wildfires that were raging.

      At the time, there was no means of containing a wildfire, so the fires burned until nature put them out. That was nearly 150 years ago. In that time, there have been major fires in many parts of the world; Australia, Russia, China, Germany, and so forth. Forest fires have happened for a very long time and almost certainly were going on from the time that there have been forests, long before people occupied the area.

  1. There should be no need to burn, which will always lead to the possibility of fires getting out of control, especially if the land has had no rain for months.

    I live near the English National Forest and regularly walk through it. This is a managed environment, and that includes taking out the “underbrush” so that trees can develop properly. This is dragged out manually and disposed of at another location – not by burning but by shredding and composting.

    In some forest areas in the UK, heavy horses are used to do the dragging, so that other trees and the land surface are disturbed as little as possible.

    Forests are natural repositories of carbon and it is very important to keep that carbon in the soil and not return it to the atmosphere if at all possible.

    • With the amount of forest land in the US, the cost of removing the forest debris would be extreme, probably approaching a trillion dollars a year. in many areas, there are also no roads for debris removal. Leaving it on the forest floor vastly increases the fire hazard and in many places makes it nearly impossible to replant trees.

      I personally think that it is wasteful to simply burn the slash, yet I fully understand the necessity. The 42,000-acre fire that burned a few miles from town a couple of years ago is an example. The land is very rugged and steep, increasing in altitude by about 1,500 feet in a matter of about 2.5 air miles. If left as it was, there still wouldn’t be a forest there a century from now, guaranteed (all the seed trees were burned) and erosion would have been extreme. Yet, it couldn’t be replanted with all the debris there, either. The debris must be cleared prior to planting. This has been done and the forest litter will probably be torched next year, hopefully in the early spring, when everything is still moist.

      On a positive note, the amount of carbon that will be released into the atmosphere will be somewhere around one one-thousandth of the amount that was released by the fire that burned that forest.