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Logging Slash

Seventy-five years ago, when bulldozers began to be used to log the redwoods, a common practice began of blading logging slash from a landing as far as a dozer could push, usually that meant into a clump of redwoods. Large piles of cull logs, bark, branches, broken log ends, and dirt were shoved into these logging slash piles, usually being left to rot. The new California Forest Practice Rules of 1975 outlawed this practice. At about the same time as the enactment of the new rules, I was just starting out in forestry, and began to notice that those redwood clumps associated with those large slash piles seemed to be the best growing, and healthiest redwoods in an area. I also learned in a college forest soils class that organic matter, in the form of humus and leaf litter, in a forest increased soil moisture capacity, and was where forest nutrients were mostly found. This introduced me to the “good” of logging slash.

Logging slash in the redwoods rots, and becomes forest humus which is a benefit for forest productivity. In my forest, I call these slash piles rot piles. When logging, I place them in association to redwood clumps, and not into them. The bigger these piles are, the better these piles are at doing their job. Redwood roots love them. All kinds of critters love these rot piles as well including arthropods, reptiles, amphibians, mollusks, and mammals.

Of course there are negatives regarding slash piles as well. They burn, as does forest humus, just like all fine fuels in a forest. This is part of the “bad” of logging slash. So there is an on going conflict between those who want to increase forest humus, and those who want to reduce forest fire risk. We even had a President who advocated for “raking the forest”, which is likely a good idea in the defensible space around your home, but no where else in the forest.

What I have noticed is after going through a winter, large slash piles retain moisture and can be difficult to burn the following year. These piles will burn, but not as intensely as one might imagine. Another “bad” of logging slash, mostly seen outside of the redwood region of California, is the build up of various wood boring insects that leave slash piles, and attack and kill nearby living trees. In this case, large slash piles can be a big problem.

Most significantly, logging slash piles can be “ugly”, particularly when they are positioned to catch one’s eye. Ugly slash piles conjure up negative connotations, too, simply because they are ugly. “They are a fire hazard”, “They are dangerous”, “They are environmentally damaging”, etc. The current controversy on Jackson Demonstration State Forest is largely based on many people’s negative perceptions of eye catching, ugly slash piles. “Those slash piles need to be removed before the whole forest, and neighboring area is all burned up”.

Logging slash piles, which become rot piles, in the redwoods need to be seen as mostly a benefit, if utilized properly. They are not as much of a fire hazard as we might imagine, either. And they if they are not eye catching , they don’t need to be ugly. Rot piles serve the same purpose in a healthy forest as rotting logs, or “heavy woody debris” does.

There is also a lesson from that long outlawed logging practice of bulldozing logging slash into redwood clumps, sometimes the unintended consequences of uncaring human enterprise are good. And the reverse can be true as well. Caring people who act to eliminate slash, and slash piles in the forest can be eliminating an important part of a healthy forest.


  1. Michael Koepf August 2, 2022

    Question: So, why push them into piles at all? Why not leave the slash where it’s dispersed to accomplish what it does in rot piles?

    • George Hollister August 3, 2022

      The advantage of piles is better moisture retention. Moisture is what promotes decay and the creation of humus. Dispersed slash dries quickly, decays slower, and provides limited benefit for tree roots. A slash pile is equivalent to a large rotting log. Notice how tree roots intrude into rotten logs. The roots are there to extract moisture. For those who like critters, moisture also provides better habitat. Slash piles, the bigger the better, do exactly the same thing, and the redwoods fortunate to be associated with slash piles benefit from them.

      • Michael Koepf August 3, 2022

        Got it. Thanks.

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