Low-impact forestry, and a good weekend’s work

Beautiful late winter weather this weekend, and I took advantage, making a solid dent in the remaining selective thinning for the high-octane maple trees.  This is an ongoing project to plant a string of sugar maples that have been specially selected by researchers at Cornell to produce a higher concentration of sugar in the sap.  We’ve located these trees along the south side of a stone wall heading down towards the water, with a sufficient slope that eventually we will be able to run a tube system to collect the sap.  Now, I will be an old, old man by the time these trees are ready to be tapped, but somehow that doesn’t seem to dissuade me.  Besides, in the meanwhile, the project improves the woodland, produces firewood for low-carbon heating, and gets me much needed exercise.   We’ve got our low-impact forestry technique pretty well worked out at this point, so I thought I’d describe it in some detail.

In the early part of the 20th century, almost the entire island was bare of trees after a period of intense shipbuilding and homebuilding on the coast of Maine.  (The word among local carpenters is that woodworkers of any significant talent were employed in the shipyards, and the rest did the relatively simple terrestrial construction; given the funky things I’ve seen in remodeling old houses around town, there may be some truth to it.)   Folks say most of the land was grazed by sheep.  The result of all this is that the forest is young, and trees in many parts of the island have grown back densely choked up, all fighting for sunlight.  Especially in places where we have additional motivation (for instance letting in sunlight for the maple trees), we have chosen to selectively thin the existing stand, both to produce firewood and lumber and to increase the quality and value of the remaining trees.  Our approach is to cut out trees that are poorly formed or have been overtopped by their healthier neighbors, leaving an intact but sparser well-proportioned stand of mixed species, consisting of the nicer trees in the pre-existing population.  It’s hard to say what fraction of the total volume of wood that we remove; I’d say it’s no more than half.

We’ve had neighbors hire professional loggers to perform a “selective cut”, which in practice often seems to involve cutting off all the valuable timber, leaving a few trashy trees, and tearing up the ground with heavy skidders.  In the thin ledgy soil of the Maine coast, this can be a disaster, with increased wind loads and damage to the root structures of the remaining trees leading to cascading blowdowns.  It can take decades for the forest to recover from this sort of mistreatment.  A few hearty souls do horse-based forestry; this is much lower impact but requires specialized skills and delicate equipment that I have no hope of implementing under the current circumstances, not to mention the need for at least 5 acres of grass to support a team of workhorses.  So we’ve taken a middle approach.

For felling, personal gear consists of sturdy boots, short gaiters (great for keeping sawdust and snow out), kevlar chaps (with fibers which bind up the saw before it can cut into your leg), gloves, safety glasses or shades, and a helmet with earmuffs and a face screen.  Being a desk jockey I use a relatively modest Stihl 024 chainsaw with a 16″ bar; it’s light and has plenty of power for most of the work we do.  To make the trees fall the right direction, the tool of choice is a “rope-a-long”, a ratcheting hand winch like a come-a-long but which works directly on 5/8″ or 3/4″ rope – and a short, light aluminum extension ladder to set the rope up in the tree.  A hammer and wedges are helpful for larger trees with a modest lean; most of the stuff I was cutting yesterday was under 12″, and wedges don’t fit in the back cut at the same time as the saw.

The basic tool for moving tree-length wood is an older 25hp Kubota 4WD tractor with a Fransgard PTO winch.  This setup is probably 1/10th the weight of the average skidder, small enough to fit through tight spots, and much lighter on the landscape.  When the ground is frozen with snow over it (as was still the case this weekend in most spots), the impact is truly minimal.   Because both my parents and my sister have old-fashioned wood-fired cookstoves, and because we have a hard time letting anything go to waste, we buck even spindly stuff and tops down to 2-3″ into 4′ lengths, and stack it to be collected subsequently with a cordwood hauler made out of an old pickup frame with four stake pockets welded on in the corners.  We haul the wood to a staging area accessible to road vehicles, then we dice it up and split it for our own use, or if there is extra sometimes my dad sells it in 10′ lengths to neighbors who want to work up their own.

This weekend my goal was to extend the area of thinning down the hill over a relatively steep area with a bunch of rocks.  I picked out a route that looked like relatively clear sailing for the tractor; it crossed the stone wall through a pre-existing opening and proceeded diagonally away from the wall to a natural clearing overlooking the hill.  The smaller stuff I bucked and dragged by hand up to the top of the hill; anything over 5 inches or so I limbed and then twitched upslope with the winch.  The cable is rigged with a grab hook and two sliders, so three logs at once can be slung with chokers and twitched – or more if they can be slung together.

One of the most distressing things that happens in traditional selective logging operations is the severe damage to the bark of the remaining trees at ground level, from dragging logs past using heavy equipment.  Besides just paying attention, picking a favorable skidway, and going slower, I’ve found that it’s pretty effective to strategically leave a few stumps 18″ high or so on either side of the skidway, positioned so as to protect the trees that remain.  Everything else should be sawed off as close to the ground as possible, so as not to pop a tractor tire.  Another useful trick that helps a lot when winching upslope in rough terrain is to rig a sling in a strategically-positioned tree with a snatch block about as high as I can reach; a little additional upward angle on the line of pull makes a big difference in the ability to bump over rocks and stumps.  The winch has a clutch in it that limits the pull force so you can’t damage the equipment when the pull line fetches up.

Anyway, I’m pretty happy with the overall procedure and its results – good exercise, an improved woodlot, and stovewood for my grandparents and the rest of the family.  The weekend’s activity probably consumed around 2/3 gallon of 2-cycle mix and 1-2 gallons of diesel, and produced maybe 2-3 cords of firewood, equivalent in heating value to somewhere around 300 gallons of heating oil. [Of course, by the time its diced, split, and transported 1/2 mile it might be 2 or 3x as much petroleum input.]


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