Friday, March 9, 2012

Sustainable Wood Lot in Dry Climate

What does it take to meet a household needs in wood - at least when it comes to keeping the house warm during the cold months of the year? A wonderful question to ponder when engaging in permaculture design of a homestead, neighborhood or community.
The case study described here is our own farm - located at 6800 feet above sea level, in dry climate (around 7" annual precipitation) with long cold winters and very hot summers. A lot must be said here and now about house design - before we attempt to keep a dwelling livable, we really need to answer some questions about its suitability to the climate in which it is built. Sustainable woodlot is, in the ideal world, attached to a sustainable house! A house that is designed to function in its climate. For dry cold mountain desert climate, where we are trying to keep cold and heat out for most of the year,  we go with "Super-insulated envelope (walls, roof, windows, doors - and floors!)" - in our case it is strawbale exterior walls. The next task is to have good enough thermo-mass in the house - something dense that can maintain desirable temperature in house. Cement (or brick) floors, adobe walls store heat - which means that when we burn our own home-grown firewood, we are investing the heat into the house, and not into the atmosphere. A well-designed burning device is the next component to ponder - a masonry woodstove is absolutely fantastic for superior performance and efficiency if you are building your house from scratch.
This is our "typical" distribution of shade trees on the landscape - large open stretches of land, with hedges and windbreaks and random shade trees. This is not a native landscape, this is a farm, i.e. the land is irrigated and thus is more vegetated.
Our woodlot is not really a designated block of woods, it is rather a conglomerate of all shade trees, old and young, that grow on our land. The size of the land is somewhat hard to pin down - we live on 10 acres with 7 other households, though none of them seem interested in gathering firewood. We also don't have a solid canopy over the 10 acres, nor do we "harvest" from the entire land. It seems that about 2 acres of diversely vegetated and used land is what it takes in essence to provide us with 90% of our firewood. The key here is labor and equipment. To make firewood out of a tree takes some serious labor. That portion of firewood harvest is approached on a community level - with hired help to prune all of our trees on the entire communal land. The prunned parts are then cut into 2' logs. Our desert trees don't get too large in their majority, so splitting the logs has not been our issue - we simply burn them as they are, at about 9" diameter - they burn well once the stove gets going.
A stack of elm kindling/sticks - this is one has gone through the goat pen first! The leaves were stripped by the goats, converted into milk. The woody remnants are cut into smaller pieces for winter heating.
The rest of the firewood comes from hand prunning old groves of apples, apricots, native plum trees. Elm trees that grow here in abundance shed their branches in each and every windstorm. Just what comes in after cleaning the fallen branches is nearly sufficient anyway - and these can be broken down by hand! No chainsaw, no safety concerns (I don't like chain saws!) - no gasoline. Simply a few firewood boxes and 20 minutes here, 20 minutes there, and you have a pile of "kindling" or small diameter sticks that burn like a charm, and keep the house warm and cozy.

Goats eat green twigs first, and later the twigs move on to their firewood re-incarnation. 

The firewood harvest is ongoing - spring, summer, fall - each season brings its share. In the spring and summer we feed tree twigs to our goats.  The resulting mess of twigs is then handled on a daily basis by quick (15 minutes or so) clipping engagements - while the twigs are moist and fresh, they are very easy to clip with hand-held prunners into small neat twigs. Each clipping session produces about 1 winter day worth of supplemental firewood (with larger logs used as well). Woodburning stove is a part of recycling of nutrients, as it is used for cooking as well.

Late spring, and the outdoor twig storage is quickly replenished - the structure against the house on the left is a nature altar of sorts, and a firewood stack at the same time.
 Every third year we buy a cord of high quality firewood, and add it to our mix of twigs, on-site larger firewood and prunnings. A cord lasts us for three winters. Our house is passive solar, so we definitely are not burning as much firewood as a conventional house of the same size would. Our balance is an end result of a carefully orchestrated interplay of house/land/lifestyle/design. The firewood from our accidental wood lot (we did not plant these trees!) is sufficient to a large degree, though.

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