When you thin hardwood, the new growth rings are larger. Does this mean that this part of the tree is more prone to warping and twisting? Or is this something with hybrid or fast rotation trees?
Mainly with the hybrids on fast rotation in tree farms...but as an extreme example since I mill "yard trees" I have seen trees standing alone with no competition with 1/2 or less the growth rings of the same species from the timber.
I happen to have a picture in my old gallery here of a freak walnut. It was in a guys yard that backed up to a farm field. He had lots of fertilizer run off for many acres where this tree grew. This tree came up volunteer after he bought the place and he just mowed around it. He had only lived in that house for 15 years...the tree was 20" diameter and nearly 50' tall. I have milled the same size trees that are a minimum
of 50 years old.
Illinois walnut for slow growth has maybe an inch of white sapwood on a log this size, this tree is was 3"-4". It was shooting up like a weed.
The point of this story is I was sort of excited to get this tree when the guy said he felled it to make room for a new garage...I just wasted gas milling it. I was hoping for something unique since I like the contrast of walnut sapwood in my projects some times. What I got was a pile of lumber that cupped beyond belief, what did not cup simple busted right down the middle. It was very unstable due to it's fast growth rate.
I thought the original post was about softwood framing material, so that is why I jumped in with the plantation explanation. Most softwoods naturally grow faster than most hardwoods. I cannot speak on hardwood forestation/harvest because I am not familiar with any timber industry companies doing that. Sure cut out old growth and replant fast growth/one species (usually softwood), but not plant a managed long term hardwood crop.
I have to add thinning hardwoods like you mentioned is healthy for the forest overall and to weed out the lesser trees makes the stronger ones thrive. Not grow at an unhealthy fast rate, just grow well.