Well technically it already is a single trunk. The question is whether to remove half of a fork and turn a forking trunk line to a single sinuous trunk line.
Lets examine a maple in nature and how they might grow.
A maple may grow as a single trunk with a semi round ball of foliage. The trunk forking rather low on the stump and moving skyward.
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Many times the trunk of a maple may be built out of many trunks emanating from a clump form. This is how many Acer Palmatums in a yard tend to grow. Unless one removes some of the trunks early these trunks can grow and move outward in fanciful shapes searching for light.
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As bonsai we deal with a tree on a very small scale. As shohin the scale is further reduced by half again or more. To build a maple tree with clump style looking trunks would very difficult indeed. Not impossible but harder to keep in scale. So Wayne's trunk starts as a single trunk and forks above the base of the trunk. This is a very natural look for a maple. At this point it seems bulky but that is because the stubs of the forks are shorter and have no secondary or tertiary branching going on.
If we remove one of the forks we are moving into what I call "main stream bonsai culture". We are taught early by teachers and books to prune for taper. Taper this and taper that. Well taper on a bonsai is good and helps convey a compressed image of a real tree to a small image 18 inches tall. Even in a shohin bonsai tree the sumo type trunks are popular for the powerful imagery they convey. But maples are not powerful, they are graceful and feminine and moving away from that means that forever more the image must look more powerful and masculine.
Removing one of those forks also means that branching will now follow a more orderly style of arrangement. In looking at the images above and the fullness of the foliage and branch structure, it is easy to see that the branching is much more laid back and more free. The branching now will follow the more traditional one, two back branch format cork screwing up the single tapering trunk. Probably the most un-natural shape for a maple. I too have many of these type of "pine tree" shaped maples.
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While these trees have a beauty all their own they do not really scream maple bonsai. What if we were to radically slant the trunk to the right or left and develop one of the trunks and slowly inhibit the growth of the other. The wye shape of the tree as it is contributes to the symmetrical nature of the wye. It now has the appearance of a slingshot and they will be hard to disguise. If the trunk were allowed to grow out in the ground it may look much like this tree which on its own looks pretty good. I would be happy to work on a tree like this as it could be refined further.
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If the wye's were allowed to grow out the tree could look much like this.
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By tipping the tree and allowing one of the wye's to grow longer an image like this might be achieved. Looking and finding pictures like this to compliment this article is very hard indeed. My point is to think about this choice and be ready to style accordingly.
Hope this helps.
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