I think it is feasible that the boreal forest followed the melting glacier by just a few years and that the forest 11,000 years ago, with some variations, looked a lot like the boreal forest of today. One of the striking ideas, though, about the end of the glacier and the return of forests is that there is good, solid evidence that humans were traveling through that forest and living just north of the White Mountains at the face of the retreating glacier roughly 11,000 years ago.
On what had been the northern shore of glacial Lake Whitefield, mentioned above, a number of human artifacts have been found that date to about 11,000 years ago (Bosivert, R.A. 1999). Dikes of igneous Rhyolite found nearby in what is now downtown Berlin, NH, are the source material for these artifacts which are comprised mostly of fluted points (arrow heads) and what could have been a fleshing tool, or scraper. The dating of these artifacts is complicated. Marland and Katherine Fowler-Billings and Richard Goldthwait who, in concert, had pieced together the currently accepted framework for the glaciation of the Presidential Range of the White Mountains, were called upon (in 1956) to help date the sites where some of these human artifacts were found in Jefferson and Colebrook, NH. The accuracy is still a little shaky for technical reasons related to the Carbon Dating process, but if the data is reasonably close we can say that humans were in the White Mountains as the glacier was ablating
Most histories of American natives begin in the early 1600s as if they arrived here a few steps ahead of the Europeans. A vast amount of time passes between the melting of the last glacier from the White Mountains and the arrival of the first Europeans. Nearly ten thousand years goes by. The non-written history of North America prior to the European invasion is somehow skipped over as if it is too meager, or inconclusive. The confounding part is that there definitely were people here in this part of New England all during that time.