My grandfather told me about a practice: girdling/ring-barking (not sure which was employed) of pine trees in order to make the wood stronger. Now, he didn't give too many details, so I had to do some research. He said the resultant, strengthened wood is called adel, adl or al, which is Norwegian.
When I searched for it, I found that these terms mean the same as heartwood, but in the context of pines. I believe that this process he explained in essence just strengthen and/or expands the heartwood of the pine. Such pine wood, that contains higher amounts of heartwood, is called ore-pine, and this Wikipedia article states that this was achieved through the removal of branches, as opposed to girdling/ring-barking, which is what my grandfather said.
Now, whether the mechanism of expansion/strengthening of the heartwood is via branching or girdling/ring-barking is one question. However, the question I am most interested in, is the mechanism of how this process happens. I know it has something to do with the increase of resinous substances in the wood, but what I'm wondering about is if this strengthening is happening via the "wood wide web". When my grandfather started talking about this, I said that it probably happened via the wood wide web. The damaged tree sends out information of its damaged state, and the other trees in its vicinity divert more resources to it, leading to the strengthening and/or expansion of its heartwood. My grandfather however, said this process did not involve the wood wide web, and that this process happened completely locally at the tree.
Which is correct (if either)?