Ryan,
So given your requirements, climate & soil, I have a couple of thoughts. But first, how are you starting these guys off? Seed? Live tree w/root ball? A cutting? Something else I missed?
At any rate, assuming that you are starting off with small stock, I would space the black locust close together, maybe even as close as 2-3 feet apart, and then thin as they grow. This will help you to get an abundance
trees on a small acreage, and give you some initial small poles, and then let the larger ones grow bigger until you are ready to cut them. I would consider keeping the black locust separate from the chip-producing section for ease of handling.
For the chip production, I would consider any or all of the following: poplar, cottonwood, alder, silver maple all as upper story trees. I would also consider something like Russian or Autumn olive for a lower story. All of the species I have mentioned are fast growing and are fairly soft wood. They will give a plenty good volume of chips and they will tend to break down quickly in a garden.
Autumn olive especially is useful for chip production (and not much else). It easily coppices, grows quickly, spreads to any open part of
land, and low growing branches will even
root into the ground and start a new bush.
As far as spacing, I would not get too concerned about spacing Autumn olive. It pretty much spreads on its own. As far as the taller trees, I might start with double or triple staggered rows spaced 5’ apart to start, then thin to 10’ apart after an initial thinning harvest. In short order you will have more chips than you know what to do with.
Hope this is helpful and please keep us updated.
Eric
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