I have decided, at least on a small scale, to experiment with and test the suitability of American Beech as bonsai material. Beech are a mainstay of the temperate deciduous forests I love, and they are readily available for collecting.
Problem number one, as the Latin name suggests, is that American beech, Fagus grandifolia, have big leaves. Grandi = big. Folia = leaves. I look forward to being able to address leaf reduction on the species eventually, but I have only been collecting beech at one or two specimens a year for 4 years so I don’t have trees at a level of refinement that answer this topic yet.
At this early phase, I am prepared to report on only two things, each with a different degree of confidence.
First, THEY SURVIVE COLLECTION. I feel confident in saying this. Of the beech I have collected, all but the largest attempt survived the collection process. That’s six successes out of seven attempts, not a bad rate. The one failure I had was really oversized and I probably shouldn’t have attempted it in the first place. Attempting to collect large specimens may be less likely to succeed, but I believe there is a significant range on the smaller end of the scale, easily up to four inches in diameter or so, that is very likely to survive when collection is done carefully.
A significant factor in successful collection is timing. I like to collect when the buds are starting to lengthen but before they open. That said, I have also found that the jostling of the digging will shake a still-tight lengthening bud to the point that the leaves will begin to emerge during the process of digging and transporting back home. So handle with care!
Second, THEY ARE SENSITIVE TO REPOTTING & ROOT PRUNING. Of this I am less certain, and indeed it seems contradictory to the first conclusion. Nevertheless, each of the few trees that have been repotted, usually a couple of years after collection, have really seemed to sulk about it for some time afterward. Following a repot with root pruning, certain branches may show significant weakness and many of the leaves across the tree will partially brown or show other damage.
One month ago (at the end of April in Northern Virginia) I removed the tree below from the box it had been recovering in for two years. I completed this operation with the same timing I described above for digging. The buds were lengthening, some of them significantly.

Beech before repotting with extending buds
I did have to remove some unsightly roots in addition to some more general root pruning you would expect in order to get it into a smaller pot.

Beech in its new pot before branch movement
I also did a small amount of branch movement. You may be able to see the first branch crossing in front of the trunk line. One thin branch on the right was wired out of the way, and this larger first branch was pulled back toward the smaller trunk in the back with a guy wire. Can you see the difference above and below?

Beech with a couple of low branches wired back
The tree hasn’t done too badly, but there are a lot of brown edges and some leaves are smaller than expected, as if starved because the root that fed them had been shortened or removed. This includes the small wired branch, so I should pay attention in the future to see if wiring impacts leaf growth.

Damaged and weak growth following repot
Below is how it looks today, one month from repotting. Not bad, but this is the “thinnest” the leaves have been on this tree since being collected.

Just for comparison’s sake, look how full the beech below is a little over a year from collection.

Another beech with full leaf canopy
With feeding and time they usually demonstrate a full recovery, but I have lost one small small beech after keeping it for three years. It did not survive the winter following a repot. It just didn’t seem strong afterward and this is the only reason for not surviving I can put my finger on.
I will continue to watch, test, and report back. Stay tuned.