Wednesday, October 31, 2012

The Giant Sequoia and Some Random Thoughts on Trees and Wood

It is one thing to see wood at a lumber yard and it is quite another thing to see it in the form of a living tree.  Unlike the stuff in the lumber yard which gives little evidence of where it came from, the living tree obviously speaks for itself.  It is not a product but an individual being with a considerable amount of character that makes it distinct from others of its kind, especially when old.
The musings I am about to deliver on the nature of wood were prompted by a trip to Kings Canyon and Sequoia National Parks.  The two parks are adjacent to each other, with Sequoia to the south and Kings Canyon to the north.  The only way to approach these parks by car is from the Central Valley of California.  Kings Canyon is adjacent to the city of Fresno and Sequoia is adjacent to the city of Visalia. Giant Sequoias can be found in both parks, although Sequoia National Park has more of them. Coming from the Central Valley which is flat and almost devoid of trees except for fruit trees in the orchards, it is hard to imagine that one is about to enter a mountainous zone where the huge sequoias live. 
But on to some pictures. I would like to say off the start that it is impossible to convey the massiveness of these giant trees in photographs.  The best one can do is show part of the tree with a human or two next to it for scale.  But even then, the photograph cannot capture the sense of presence that these large trees convey. Nevertheless, here are some photographs.
This trunk of a Sequoia has been hollowed out by fire and decay and so it is possible to walk through and along the trunk. 
Here is another sequoia that has fallen.  Someone cut a hole through it that one can walk through. The hole by the way is about seven feet tall.

Here is a picture of the tree named the General Sherman.  This is the world's most massive living being.  It is suspected that some of the trees cut down when logging first began were larger than this, but General Sherman is currently the largest individual.  Its diameter at the base is in excess of 30 feet. 

 And here is the root ball of a recumbent sequoia, 30 feet from side to side.
 And using a deer for scale.
 And more humans for scale.
 And a tree hugging human for scale.
Even the branches of these trees are huge.  This one fell off a tree and the park service left it laying where it fell to give people an idea of their large size.  The largest branches on the General Sherman are about 7 feet in diameter.

The sequoias are not the tallest trees in the world.  That distinction goes to the coastal redwoods.  Neither are they the oldest trees. That distinction goes to the bristlecone pines of the White Mountains, one valley to the east of the Sierra Nevada.  But the sequoias are the most massive trees. Their trunks seem to be columns of almost constant diameter rising some 300 feet into the air and then seeming to end abruptly in the older specimens.  

Someone took a slice of a sequoia trunk and propped it up at an angle for the edification of the public. This slice represents roughly 2000 years of growth.  Age is determined by counting the annual growth rings.  The age of standing trees has to be estimated because there apparently is not any equipment that can remove sample cores of the requisite length, roughly 18 feet needed to count all the rings from the center of the tree to its edge.

 This is a side view of that specimen.


And here is a closeup of the growth rings in that slice.  The top of the picture is closer to the center of the tree where the older wood resides.  The crack running horizontally through the picture is a fire scar.  Moving downward toward the crack, the growth rings get ever closer together, an indication of ever diminishing growth.  After the fire, there is an explosion of new growth that again diminishes over time.  Apparently, fires burn the vegetable matter on the ground and release nutrients into the soil which spur new growth for a few decades until most of the nutrients are once again tied up in vegetable matter until the next fire comes along.  Also, note the little circular impressions just above the crack.  These are probably cores taken for carbon 14 dating and then plugged. 
When botanists try to estimate the age of trees based on diameter, they look at slices like this one and try to get an average count of growth rings per inch since as this picture shows, ring density changes with every fire and also with annual precipitation.

There was no sign indicating what sort of wood these park benches were made out of, but I suspect that they were made of sequoia wood. Yes, they haven;t stopped logging sequoias.  Not all of them are protected. Some of them are on private property and some of them are in national forests which are administered by the US Department of Agriculture which regards forests as cropland meant to be harvested. Not an editorial comment by the way. If we want to make stuff out of wood, we have to cut down trees.  More on that at the end.

Here the park service has done a prescribed burn or someone dropped a cigarette. In any case, not much damage was done.  For a long time, the park service used to suppress fires but found that periodic fires are better than monster fires fueled by debris on the ground that has accumulated for too long.  Also, they found that sequoias will not reseed very well without fire.  Fire turns vegetable matter into ash, releasing nutrients for the seedlings to grow.  Fire also kills off young trees that would otherwise shade out the new seedlings. And fire also opens up the cones to release seeds.  So now the park service does prescribed burns which do little damage but reduce the amount of fuel that could produce more dangerous fires.

This picture shows young sequoias coming up with the older fire scarred sequoias in the background.  The ash and the light also allow ferns to grow.

Another view of the burned ground.  Yes the ground burns since the top six inches are a compacted mass of needles and small branches.
Almost every old tree shows fire scars. As a matter of fact, I have never seen so many burned trees as I saw in Kings Canyon National Park.  In the national forests, fire scarred trees are more rare since those are logged over on a more regular basis and fires tend to be suppressed because the trees are regarded as a crop, not a part of an ecosystem in which fire plays a beneficial role.
This is a side view of about eight inches of fibrous sequoia bark which lacks resin and therefore does not burn readily.  Bark on sequoias can be up to two feet thick and this is what lets them grow old in an environment where fires occur naturally every seventy years or so.
Here the fire burned into the trunk of the tree but the segment at the left is still alive.  Every yearn the bark spreads sideways to cover over scars and in time will cover them completely.

Here is a segment of  a branch. The heart wood is red and the sap wood is a lighter color.  The heart wood of the tree is dead.  The sapwood is the part of the tree that is still alive and growing and is where the tree adds more wood around the outside of the tree under the bark. For purposes of lumber we want heart wood because the sap wood decays more readily.
So I was curious what kind of wood sequoias are made out of or perhaps more properly, what kind of wood they grow.  Right on the ground near this broken branch above I found a small piece that had broken off when that branch came down.  It was red in color like that branch but on carving some off, I found that the red color was mostly a product of weathering and that the wood was a lighter color.  It was also surprisingly light, similar to redwood but with a consistency that felt more like cedar.  And then it occurred to me, why not?  If you are going to grow large, why not build yourself out of light wood.  Since most of the weight of the tree is in the trunk, the lighter it is, the larger you can build it.  Sequoias and other conifers don't have huge spreading branches like oaks and so most of their strength is needed to resist the compression of the mass that piles up on top of the roots, mostly in the trunk.  Hardwoods like oak on the other hand that put out large lateral spreading branches need stronger wood to resist bending forces and stronger wood is heavier.  And so boat builders like conifers because they produce long straight trunks that can be cut into long straight boards.

As a boat builder I use wood. And as a paddle maker I also use wood, especially wood from older trees since they are the ones that have the wood that is clear of knots. But to use wood without a knowledge of what happens to the forests where that wood is taken from is akin to buying a pork chop in a supermarket without knowing that one needs to kill pigs in order to make that pork chop.
The impact that the visit to the sequoias had on me was to see trees as individuals.  Young trees a few decades old, especially in large quantities tend to be rather similar in appearance and lack distinction as individuals.  Every tree seems to look like every other tree and so one can more readily regard them as a crop to be cut for use as lumber.  Old trees however, tend to be distinctive, each one different from the next and since in the case of the sequoias they may have been around for perhaps two thousand years or more, one is forced to realize that cutting one of those trees for human use deprives the rest of the world from the presence of such old trees for another two thousand years.  And so it seems that to cut such old trees is rather frivolous because the gain in lumber does not make up for the loss of the presence of the individual.  
And yet, as a wood worker, I use wood.  And since I make objects for other people, I want to give them a good product free of flaws and blemishes.  I want to give them something that looks like wood is something that is extruded by a machine. 
Perhaps I need to rethink my approach.  If I do not want to participate in the cutting of old trees, then perhaps I need to figure out a way to make paddles from younger trees whose wood is not quite as perfect and blemish free as that of older trees.  Stay tuned, I have some younger trees in mind that I will experiment with

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