Mature oak response to thinning?

[BillyB]

My land in MN had been left alone for at least 70 years. Trees have grown close together. Presently, I'm primarily concerned with oaks, mostly burr oaks that have reached canopy height, tall with narrow crowns. I'd like to keep the overall canopy but would rather have fewer, larger, and more robust looking trees.

1. If I were to thin out the less healthy looking or poorly situated ones, do you think the the crowns on the remaining ones would expand into the newly opened space or is it too late for them to expand this way?
2. If you thought new growth possible then where would it occur? Would it all occur in branch tips in the current crown or is developing limbs lower on their trunks also possible?

I look forward to your perspective.

 

[Brufab]

My land in MN had been left alone for at least 70 years. Trees have grown close together. Presently, I'm primarily concerned with oaks, mostly burr oaks that have reached canopy height, tall with narrow crowns. I'd like to keep the overall canopy but would rather have fewer, larger, and more robust looking trees.

1. If I were to thin out the less healthy looking or poorly situated ones, do you think the the crowns on the remaining ones would expand into the newly opened space or is it too late for them to expand this way?
2. If you thought new growth possible then where would it occur? Would it all occur in branch tips in the current crown or is developing limbs lower on their trunks also possible?

I look forward to your perspective.

I would think so, I have pear trees that are 40-50' tall barely any branches till the top because they grew in dense mixed hardwoods. Same with apple trees. The same land has a decent sized river going thru the 40 acres. The river is maybe 20'below the ground level. Trees grow to the light. Trees are growing towards the river where its open and on the other side of the ridge they are growing towards our road. I mean like 22.5° angles. There's mature oak and maple that are strait 24-48" dbh. But anything under 16" is growing crooked and scraggly from being choked out. The tree won't have to grow strait up looking for avail light.

 

[Del_]

Trees often share wind loading and removing some trees exposes those that are left to higher wind loading and a greater chance of uprooting.

Just tossing that out there.

 

[computeruser]

You aren’t going to create an oak savanna with broad crown trees out of a dense climax forest. If that’s the look you want, it isn’t going to work on that parcel during your lifetime.

Wind load sharing would be a real concern, especially depending on soil type and root depth in that area.

Thin if you wish, but when in doubt so less.

 

[ATH]

Start by picking the best looking oak trees that are too crowded. Look up at the canopy of those. Cut anything that is touching the canopy. This is called "crop tree release". https://www.fs.usda.gov/treesearch/pubs/14228

The aim is generally 50-75 crop trees per acre. In a young stand you may start with more than that. You may not get to that number and that is OK...the rest of the trees may stay crowded, but your most desirable crop trees will have space to thrive. Plan to release them again in +/-10 years (depending on soils, etc...).

For this to work, you need about 1/4 to 1/3 of the total height of the tree to have live branches. This is called live crown ratio. Even if the crown isn't really spread out, you need that ratio to be there or there isn't a real high chance of increased growth. 70 year old oaks should have been released 20-40 years ago...but here we are now, so work with what you have.

You may get some lower branch development, but much of the new growth will be higher up on the canopy. One way to help this further is leave some mid-story trees that will shade the oaks on the south and west sides (especially anything in the white oak family like White oak, Bur oak, Swamp white oak...). It is OK if these are below the canopy of the oak...as the oak will take a dominate position over them and they will have relatively little impact on the growth rate.

You could also just thin the whole stand down to an appropriate basal area. There are stocking charts that tell you how much to thin based on tree species, diameter, and number of trees per acre. These are designed to help maximize growth/occupy the stand with desirable trees and stop you from thinning it too much. The aren't super complicated, but I'm not gonna try to explain here either... Just start with a conservative crop tree release...

 

[Woody912]

My land in MN had been left alone for at least 70 years. Trees have grown close together. Presently, I'm primarily concerned with oaks, mostly burr oaks that have reached canopy height, tall with narrow crowns. I'd like to keep the overall canopy but would rather have fewer, larger, and more robust looking trees.

1. If I were to thin out the less healthy looking or poorly situated ones, do you think the the crowns on the remaining ones would expand into the newly opened space or is it too late for them to expand this way?
2. If you thought new growth possible then where would it occur? Would it all occur in branch tips in the current crown or is developing limbs lower on their trunks also possible?

I look forward to your perspective.

Don't over the sunlight shining on your trunks or you will get a lot of epicormic growth sprouting from your trunks

 

[BillyB]

Trees often share wind loading and removing some trees exposes those that are left to higher wind loading and a greater chance of uprooting.

Just tossing that out there.

Thanks for the warning, will keep it in mind.

 

[BillyB]

You aren’t going to create an oak savanna with broad crown trees out of a dense climax forest. If that’s the look you want, it isn’t going to work on that parcel during your lifetime.

Wind load sharing would be a real concern, especially depending on soil type and root depth in that area.

Thin if you wish, but when in doubt so less.

How about an open woodland/dense savanna with liberated closed grown trees? Still quite a bit of wind protection. Besides remaining trees am in a small basin.

 

[BillyB]

Start by picking the best looking oak trees that are too crowded. Look up at the canopy of those. Cut anything that is touching the canopy. This is called "crop tree release". https://www.fs.usda.gov/treesearch/pubs/14228

The aim is generally 50-75 crop trees per acre. In a young stand you may start with more than that. You may not get to that number and that is OK...the rest of the trees may stay crowded, but your most desirable crop trees will have space to thrive. Plan to release them again in +/-10 years (depending on soils, etc...).

For this to work, you need about 1/4 to 1/3 of the total height of the tree to have live branches. This is called live crown ratio. Even if the crown isn't really spread out, you need that ratio to be there or there isn't a real high chance of increased growth. 70 year old oaks should have been released 20-40 years ago...but here we are now, so work with what you have.

You may get some lower branch development, but much of the new growth will be higher up on the canopy. One way to help this further is leave some mid-story trees that will shade the oaks on the south and west sides (especially anything in the white oak family like White oak, Bur oak, Swamp white oak...). It is OK if these are below the canopy of the oak...as the oak will take a dominate position over them and they will have relatively little impact on the growth rate.

You could also just thin the whole stand down to an appropriate basal area. There are stocking charts that tell you how much to thin based on tree species, diameter, and number of trees per acre. These are designed to help maximize growth/occupy the stand with desirable trees and stop you from thinning it too much. The aren't super complicated, but I'm not gonna try to explain here either... Just start with a conservative crop tree release...

Very helpful! Appreciate all you shared and will look into these things further.

 

[BillyB]

Don't over the sunlight shining on your trunks or you will get a lot of epicormic growth sprouting from your trunks

I realize epicormic growth is undesirable for commercial trees but these are for pleasure. Anything wrong with it in this case?

 

[Del_]

Words of wisdom: (I read these words somewhere.)

When in doubt about removing a tree.

Don't.

Unless you have good reasons.

So far I've yet to see a good reason other than the owner has an idea of what they'd like the trees to look like.

Meanwhile the trees have grown as their millions of years old evolving genetics have led them.

All too often human managed trees suffer when bending to our wants.

Lots of good advice being given and I can't find fault in any of it.

 

[ATH]

I realize epicormic growth is undesirable for commercial trees but these are for pleasure. Anything wrong with it in this case?

Cleaner trees look better (personal opinion).

I point out to people who tell me that they aren't interested in timber that a saw log tree can feed the animals and look pretty too. If you are gonna grow a tree to feed the wildlife or to look pretty, why not grow one that might have commercial value down the road too.

This is especially important for multi-generational ownership if that is an important value for you/your family. You may just want to look at the trees. But one day your grandchild who lives out of state will own. They'll be busy with their family and never make it back. They'll get a tax bill right after they had to replace their furnace and think "yeah...I know grandpa loved the place, but I think it is time to sell it". But wait....there is some timber revenue to be had! They can have a nice timber sale, keep the woods, then your great grandchild is back at the property taking walks or hunting.

The epicormic branching is why I recommended leaving some mid-canopy trees to shade the trunks of the white oak species.

 

[esean]

Assuming they have healthy crowns, they should respond with increased growth. I'm sitting right now looking at a section I cut out of a forest-grown white oak that fell a few years ago. It was 180 yrs old. It was suppressed for the first 125 yrs, and was only 11" diameter at that time. It was apparently released then because the growth rings expanded greatly. Over the next 55 yrs it grew to 26" diameter. That's more than 3x the diameter growth rate. Depending on how tall and thin your trees are, you still need to keep in mind the warnings given above about sudden, drastic thinning.

 

[Tree sloth]

My land in MN had been left alone for at least 70 years. Trees have grown close together. Presently, I'm primarily concerned with oaks, mostly burr oaks that have reached canopy height, tall with narrow crowns. I'd like to keep the overall canopy but would rather have fewer, larger, and more robust looking trees.

1. If I were to thin out the less healthy looking or poorly situated ones, do you think the the crowns on the remaining ones would expand into the newly opened space or is it too late for them to expand this way?
2. If you thought new growth possible then where would it occur? Would it all occur in branch tips in the current crown or is developing limbs lower on their trunks also possible?

I look forward to your perspective.

Thinning out the less desirable trees would benefit the remaining oaks. Allowing them to spread out. Just keep in mind you could be exposing the remaining trees to conditions and forces the removed trees may of been been protecting them from.

 

[Seachaser]

We grow pecan trees and thinning is a common practice. The trees will be healthier and more nutrients to each tree. Some start with 20x20 and end up 40x40 or 60x60. Hedging is also practiced, and their crowns will expand in five years or less. This is in the south with prime growing conditions and fertilizer.

 

[irhunter]

My land in MN had been left alone for at least 70 years. Trees have grown close together. Presently, I'm primarily concerned with oaks, mostly burr oaks that have reached canopy height, tall with narrow crowns. I'd like to keep the overall canopy but would rather have fewer, larger, and more robust looking trees.

1. If I were to thin out the less healthy looking or poorly situated ones, do you think the the crowns on the remaining ones would expand into the newly opened space or is it too late for them to expand this way?
2. If you thought new growth possible then where would it occur? Would it all occur in branch tips in the current crown or is developing limbs lower on their trunks also possible?

I look forward to your perspective.

How much land are you writing about?

I hope, assuming you decide to thin, you'll post some before and after pics.

 

[ATpro]

One word of caution, thinning will help but make sure the thinning doesn't do damage to the trees left such as bark and trunk damage.

 

[irhunter]

While not saying, the OP should bump the system back to before wildfires were suppressed, I do think knowing what was on the land back then might be informative.

Mid-west over-stocked oak systems which have developed only after wildfires have been suppressed, and without active management, can be a mess. A mess in regard to timber value, and all the less-economic-based values as well.

https://files.dnr.state.mn.us/eco/mcbs/natural_vegetation_of_mn.pdf
Roy

 

[klinknat]

While not saying, the OP should bump the system back to before wildfires were suppressed, I do think knowing what was on the land back then might be informative.

Mid-west over-stocked oak systems which have developed only after wildfires have been suppressed, and without active management, can be a mess. A mess in regard to timber value, and all the less-economic-based values as well.

https://files.dnr.state.mn.us/eco/mcbs/natural_vegetation_of_mn.pdf
Roy

Spot on!