Replacing trees

I’m started to get short on space for my food forest and I’ve been thinking about replacing some shade trees with chestnuts. I’m thinking though that if I cut down the shade trees and immediately replace them it’ll be years before I get any shade back again. I’ve read some books suggesting you could underplant the existing trees and then cut them down when the new ones are tall enough. Something like what happens in a real forest. My question though is that while that sounds good, how do you remove the older trees without severely damaging the new chestnuts?

My gut feeling is that while it's theoretically possible to plant new trees and then eventually fell the old ones, in practice, this probably would not work, at least not with chestnuts or most food trees. Chestnuts are an overstory tree themselves and need sunlight, as well as lots of water and nutrients. If it were me, I'd bite the bullet and fell the trees. You're resigning yourself to a few hot summers, but it'd be worth it to me to get the chestnut production in the long run.

Another thing you could consider is planting things like paw paws, currants, etc under the shade trees as these plants can tolerate some shade, though I think giving them some sun will definitely help their production.

One option may be to do some substantial thinning and crown lifting on the shade trees, to bring more light to the lower levels. The use some mid-story and understory planting beneath those, which would benefit from the increased light levels.

If your soil retains moisture well then the pawpaw is a good choice since it is an understory starting tree. Pawpaw leaves are subject to sunburn and that kills the young trees (third year is when they can start tolerating more sunlight).

Chestnuts can be started as an understory tree but will want more sun their third year, the old chestnut forests growth pattern of tall straight trees shows they started life reaching for sunlight (that means they were understory starters that took over once they grew tall enough to shade out the other trees.

If you tall growing shade trees that produce food the pecan is one of the best suited for that, they start in nature as understory but benefit from more and more sun as they grow.
Original stands have long, straight trunks and evidence of disturbance that gave them the sunlight they wanted to grow.
Pecans take about 20 years to get into full production mode and they tend to be alternate year producers, the paper shells are the most popular for growing since they are easier to crack.

I'm torn on what to do.  The tall shade trees have some major problems.  They have been dropping huge limbs over the years.  I'm fairly tempted to just cut them down, start fresh with chestnuts and take the heat gain hit for a few years.  
I'm still thinking about what you said Bryant.  I should be working with the system and under planting it instead of fighting it with a chainsaw but the long term benefits of having chestnuts is hard to walk away from.  I have a lot of fruit trees and nothing as far as nuts or starches go.  

Chris,

What do you value more the shade or the fruit? I think you have to start there. There are some faster-growing fruit trees like mulberries (your neighbors will hate you for the purple bird poop), but it can be done. If you are going to stage the replacement, I have been successful with a nice mulch donut to inhibit competition, I root prune the established tree in the area I am planting the successor, and most of them get established pretty well. I am felling the established trees this month before they can send their energy to the roots and the new generation should grow aggressively in the spring.

Yeah you're right.  I value the nuts more than the shade

Bryant RedHawk wrote:

Chestnuts can be started as an understory tree but will want more sun their third year, the old chestnut forests growth pattern of tall straight trees shows they started life reaching for sunlight (that means they were understory starters that took over once they grew tall enough to shade out the other trees.

I have a large woodland of mixed chestnut and oak.

For the most part the chestnut is managed as a coppice, where the stems are cut back every 15 years or so. Coppicing results in a generation of stems from neighbouring stools that all grow up at the same time racing for the light. In this situation it isn't really an understory, as such. If the stools are left they frequently die back to one or two main stems.

My understanding is that this was historically how many of the chestnut forests were managed that are now presenting as mature forests.

any idea how big a chestnut tree trunk is after say 30yrs?  

This breeder http://www.chestnuthilltreefarm.com/store/pg/35-The-Dunstan-Chestnut.aspx says of their 34 year old orchard:

In 1984 we planted a second grove of 500 trees using both grafts and seedling Dunstans, and many are now over 50' tall and 12-16" in diameter. These Dunstan Hybrid Chestnuts show a combination of American and Chinese traits. They are healthy, vigorous, and bear heavily every year. We have chosen several cultivars that have the very best combination of nut and tree characteristics.

As to underplanting and damage when felling trees, you could hire these guys!