Pruning advice for my 16 American Elm root sprouts, 3rd year

I cut down this American Elm tree in the center of my yard in the fall of 2010. In 2011, we didn't mow for an extended period of time and then noticed about 27 root sprouts all across the yard.

Over the next 3 years, some of these sprouts died off, but a few have achieved what is to me, amazing growth. 10 of them are now well over 8 ft tall, with another 6 much smaller but growing.

I'd like as many of these as possible to grow into trees and I think I should be doing something to help manage that growth, like pruning and such. So far, all I've done is clear back grass at the base, add some tree/shrub dirt, and pesticide the leaves.

What concerns me is that at the base, there doesn't always appear to be a "trunk" but a cluster of several branches pointing upward.

Would really appreciate any advice. Thanks in advance!

Decide on one clump that you DO NOT wish to keep, and then do some forensics.

Dig around - or better, use a hose to blast soil away from the base of where the sprouts are emerging so that you can see what/how these sprouts are anchored to. And take lots of images to document what you find.

You should see that these new stems are emerging from the old root system of the tree you cut down. Likely, these emerged from dormant buds along a primary root extending shallowly below the soil surface. As such, these will be poorly anchored "new trees" - which may be a long term liability rather than long lived new specimens.

Then again, it may just be a long term fun learning experience to see what happens...

That's what they are, taps off the roots. Plus we have a vole/chipmunk cavity playground underneath the yard, so some of those sprouts came out of holes that we filled 2 years ago.

Long term, I really wasn't sure if these root sprouts would grow into trees. Some of what I read online said they would become trees, but I also thought about the anchor part you mentioned. What's wild is some of the sprouts are 40 feet from the stump! I'm an engineer by trade, so I don't know what's going on here. Just seemed nature knew what it was doing and I'm getting a new forest from that one downed tree?

As I mentioned on a different post - reformed engineer here, at your service. What branch of the discipline, pray tell?

It should intrigue and enlighten you to delve a bit further into tree biology and structure. Too many people (engineers especially) are unaware of what goes on underground with regard to how perennial woody plants grow. Your Elm likely had (barring deep barriers) contributing root system growing as far away from that trunk as 1.5 times the tree's height. From the image provided, it looks like that tree could have been 30-40 feet tall. That means tree roots (that can sucker, on some species) extending up to 45-60 feet from the trunk of origin.

That should make most people think twice about what is so casually done in the vicinity of well grown trees. But not often enough.

So yes, you are getting a lot of regeneration from the still vigorous root system. Unfortunately, none of the new sprouts will have the stout physical attachment of the original tree with its radial root system. I have observed trees from sprouts here at the Valley (a Hackberry and a Bitternut Hickory, as examples). As they gained height and heft, they were serious wobblers and eventually refused to remain erect. You will possibly experience the same thing with these new Elms.