Posted: Mon Sep 11, 2017 3:04 pm
by dbhguru

If the forest inventory you cited is claiming the heights of the hemlocks shown are 60 feet, that number is likely to be low by 20 to 30 feet, if not more. Sixty feet is nothing for a mature hemlock. Hard to understand where such a number could come from.

We've measured old growth hemlock in the Porcupine Mtns to slightly under 120 feet. We have similar heights for hemlocks in the NY Adirondacks. Same in New Hampshire. In Massachusetts, we see them up to between 125 and 130 feet. In Pennsylvania, add another 10 to 15 feet. In Ohio, our folks have measured a 160-footer or two. In the southern Appalachians, pre-adelgid, we saw them between 160 and 170 feet with a tiny number over 170. That's pretty much the story of the species in terms of maximum height growth.