I don't know the name of the mod, but I do know what you mean. I don't think it's "Treecapitor" because with that mod you actually have to axe the bottom of the tree trunk, but maybe they updated it? The mod can be annoying and quite honestly I would not use it if I re-played Monster. Why? Because when I fly around the Twilight forest (advanced genetics flying, which is a pretty slow flying speed), oh my goodness the lag is immense... and what causes the lag? This mod is pruning every tree and cutting back on the leaf blocks with whatever algorithm it is using... and believe me, there are a LOT of leaf blocks in TF. I'm playing SSP, I'm the only one on the server!! So automatic leaf block removal is like the last thing I'm concerned about, and as I just pointed out, in fact it is a detriment to play, not an asset.