Nonsai: Growing Alnus Nigra as tall as possible in the shortest timespan

[Wires_Guy_wires]

Climate changes (as in: more prolonged droughts) are not going easy on our private swampland.

We use this swampland as a firewood production site and it's mostly populated by oaks, maples alders and some hawthorns.

Because there's a freakishly huge pig farm next to it, that has just expanded to house another 2000 animals, the undergrowth is now reaching 1.8 meters (5ft something) in height; stinging nettles and thorny brambles. They're loving the nitrogen and ammonia. But the undergrowth is causing problems. My grandfather used to chop trees back to two feet, use the trunk for wooden shoes and such, and the trees usually grew back from those stumps in a clump form. European Daisugi.
But the undergrowth has now become uppergrowth and forms a dense mat of vegetation covering the entire woodland floor.

This means there's no longer a natural cycle of taking 3 trees down in winter and the forest replanting itself, or stumps flushing out again in the spring.

So as a new manager I'm going to plant a couple thousand black alder seeds in pots and I basically want them to get as tall as possible in the least amount of time. The quality of the wood doesn't matter right now, internode length does matter. They'll get another 20-50 years of growing freely, but I want them to be taller than the undergrowth ASAP.

Would it work to strip the lower leaves, in essence doing something like a pine sacrifice branch? Any tips and advice are absolutely welcome.

 

[Rivian]

Rent goats.

 

[ShadyStump]

It might be tricky in your situation, and may be frowned upon in your area, but here it's common to burn off underbrush in the spring and fall. It's actually encouraged to help mitigate wildfires. Permission from the local firefighting officials is often required, and weather conditions are monitored to ensure that the fire doesn't get out of control.

You said internode length was a concern, but didn't say how so. Are we looking for long internodes to reduce knots and whorls for eventual woodworking?
If that's the case, relatively low light, or lights steadily moved up as the trees grow might help. A coarse growing medium that encourages thick woody roots in stead of the fine feeder roots would put more growth into the trunk and wood than into foliage. Trimming low branches while they're still young on deciduous like you mentioned is common in forestry for timber to reduce knots and maintain a straight trunk. Seems like it would also encourage top growth over branching as well. I'm not an expert though.

 

[Wires_Guy_wires]

@ShadyStump unfortunately we can't do fire, mostly because the plants growing there are very fire susceptible and it would just mean that we would have to replant the entire thing. We also have no means to control it from spreading any further; even the firefighters can't cross swampland with their trucks and it's too shallow for boats.

Internode length matters because I want them to be as long as possible, knots, burls, and all those things don't matter at all. The wood isn't used in woodworking since that act died with my gramps. The tools are spread out through the family now.
I'm in the process of germinating seeds and the plants themselves will be in half shade to produce as much height as possible. I'll be growing them in groups, in the hopes of them competing against another inside the same pot.


@Rivian do you think they'll eat thorny bushes?

 

[Rivian]

do you think they'll eat thorny bushes?

yeah, but ask the owner first

Example: