Staying Off the Soil

To not destroy a forest, human removal of logs most not compact the soil. We took the avenue of simply staying off of it, using our light-weight winch on sleds, while bigger operations might address it by using huge tired machinery or long arm reaching equipment to avoid harm. Protecting the soil is just as important, as keeping a full standing forest, when we manage, by “working with” the forest. The soil is like the placenta inside a mother-to-be, nurturing her unborn fetus. Soil compaction from heavy equipment driving over it will destroy soil’s life giving function, nourishing the plants and trees of the forest. Compaction has everything to do with soil disease and trees dying.

The following information about compaction is from Richard Hart, a forest ecologist who works closely with scientists of the PNW US Forest Service Research Station. Just as in the case of environmental conditions being a filter for optimizing genetics of plants and animals to fit their surroundings, so too are disease organisms in the soil a filter. Just as natural disturbances like wind, pathogens are a natural part of the environment; soil disease spores are always present and a part of that filter - removing trees unsynchronized with the site. Trees with genetics suitable for the site remain and produce future generations. Standing up to disturbance of one kind and another, is how a forest improves its components, the plants and animals, and thrives.

But too much of a disturbance is a bad thing because if gone completely unchecked all the plants or animals, not just the ones that disturbance weeds out, die. So Nature has evolved checks to keep the critter kind of disturbance from getting out of hand. In regards to soil, the check on disease is keeping it inactive via a natural chemical drug called ethylene, released by a bacteria. There are 3 tiers of creatures in the soil breaking down fallen wood and the one producing the drug is the 3rd tier down, feeding on the frasse of the 2 layers above it. It’s a bacteria. If something happens to stop its release of gas, the disease organisms wake up and attack the roots of trees.

Two things stop ethylene production. The first is natural and healthy, stopping the supply of ethylene when woody material in the soil has been all used up. In the absence of wood to break down, our bacteria friend making the ethylene starves, and it stops. The pathogens wake up, attack tree roots, killing the trees without the genes to stand up to the disturbance. They eventually fall down, wood joins the soil, and ethylene production starts again.

The second thing that activates pathogens is unnatural, being compaction from heavy equipment on the soil. The scale of compaction that happens during typical skidder logging is far beyond any to be found in Nature, crushing the soil column 15 inches down. Deeper, if the soil is rocky. Unfortunately, nothing exists in nature, nor can be done by humans, to rapidly overcome that degree of compaction.

Living within the first 6 inches of soil are worms, millipedes, ants and other burrowing creatures called macro-organisms. They perform the tasks of chewing up wood, digesting it and eliminating a solid form called frasse. The second 6 inches of soil harbor fungi, algae and bacteria. They eat the frasse from above, creating a finer form of it. Below them, there lives our ethylene producing bacteria, which eats the frasse of level 2 and eliminates a solid called soil plasma. Trees are able to take up soil plasma , it is so fine, through their roots, and build their own protein out of it.

When soil is compacted, tree roots can not take up soil plasma and the tree begins to starve. But soil plasma production continues and starts accumulating. At a certain level of plasma build-up, another bacteria is activated to eat the soil plasma. From this soil plasma, this different bacteria produces and eliminates a gaseous and solid form, too. The gaseous part inactivates the very bacteria that makes the ethylene. Thus ethylene gas production stops. The pathogens wake up and there is no check on them from wearing down all the trees, eventually, and destroying the forest.

In Nature, only burrowing creatures can remedy the situation by restoring the looseness of the soil over a very long time. Amongst what humans can do, along with ceasing to log with ways that compact the soil, the only thing I have come across is a large rototiller on the end of an arm reaching off an excavator. It’s brand name is a hygro-tiller. And this is just to make big lose planting holes for trees to put back the forest when the old one is gone. (Ray Graham, Rochester Washington, cvrbase@aol.com or phone 360-482-7018) So that sums up why it is important to be light, spread heavy weight out over a broad area, or stay off the soil.