Tree species can “migrate” naturally about thirty miles a century. If climate change happens faster, some may be unable to make the trip in time.
Humans, however, have already moved species. Loblolly pines, for example, have been successfully planted in large numbers significantly north of their natural range and I have seen stands of bald-cypress in Minnesota. They do not naturally regenerate that far north, but they are there – waiting – if climate change makes conditions appropriate. We may well see new associations.
On our tree farms, we have planted some longleaf pine and will plant more after our anticipated summer harvest. The farms are on the northern edge of the natural longleaf range, so a climate change would leave them in an appropriate place, providing rainfall patterns remain similar. There has also been a shift in loblolly subspecies. Most of those planted in Virginia are sourced further south. Their parents, their genetic material, is from trees originally growing in South Carolina or Georgia.
Anyway, we are going to be taking part in an experiment, whether or not we want to do it. We have to think 30-50 years in the future and anticipate that the future may not be like the past.
Reference – http://www.nrs.fs.fed.us/pubs/43455
Uneven aged management
It takes a long time to experiment with forests. This one was almost a century in the making. You really cannot do selective harvest. Sometimes you need to do clearcuts, even with uneven-aged forests and even when you avoid high grading, i.e. taking the best and leaving the runts.
I was recently reading yet another FDR biography. FDR was passionately interested in forestry. One of the first laws he proposed while in the NY legislature was about forestry. Fortunately, it did not pass. He proposed making it illegal to harvest trees below a certain size. This sounds good. It kind of works with fish, but not with trees. Some smaller trees are not younger trees. They are the inferior ones. If you cut only the big trees, over time you make your forest weaker. It is a kind of survival of the least fit.
Reference – http://www.nrs.fs.fed.us/pubs/46392