Steven - I'm open to any techniques that are tried and work, while understanding they may not work at our place. We've tried some planting around large rocks/boulders with some success, but our experimentation has been in the garden spaces instead of with trees. We have planted around 10+ fruit trees over the past 4 years, with a couple of losses. They've been planted in different areas some receiving more sun, others closer to water and in the shade until later in spring when the sun rises higher in the sky. We did this to experiment with keeping the trees from blossoming too early. The ground wasn't the best in this area, but the trees that did make it do bloom a bit later which could be helpful for late frost. The trees that have done the best are planted using the Ellen White Planting method that we learned about from an organic gardening workshop we hosted. The speaker shared about this method. The trees we planted using this particular method did extremely well and bore a great deal of fruit in their 2nd season. So much so that the branches almost broke. This particular method though doesn't help with zone temperature, but is focused on nutrient dense growing for the roots.
Methods we've tried growing within the garden spaces have been using hot spots/microclimates that are naturally occurring on our property in permaculture zone 1 and zone 2 where we plant the most items. Planting around large rocks/boulders. We have a lot of small boulders that we could use to build up around trees, but it would take a huge amount of effort to move them since we have little machinery to help. Before we do this I'm still not confident in how to best do it around trees. I haven't see how Sepp Holzer does this method in great detail. We have tried and had great success with hugalculture raised beds. People who come to our place are always amazed at how well veggies grow on these raised beds and I think part of the reason things do so well is because of the increased soil temperature early and late in the season. The heavy mulch/Back to Eden approach has also been tried and did not go well for where we live. Our soil temperatures stayed far too low and it took 3 years to get the wood chips to really break down. In the end we removed what was left and put them in a section of the garden that we weren't using to let them fully break down. Love the idea of Back to Eden, just not the best for our cooler climate and moisture level. We have no walls to plant along, although dream of creating some stone walls down the line. I'm not sure of other methods that can be used outside of greenhouses/high tunnels for trees or large bushes.
Russell - thank you for your thoughts. I was just researching seaberries and serviceberries. We have growing and doing well thus far raspberries, elderberry, currants (we'll know how well these did this spring), apple, plum, sour cherry, and apricot along with lots of different medicinal herbs and perennial edible plants. Each year we'd like to continue to expand the edible items and nut trees would be a wonderful blessing, along with a couple more varieties of fruit.
John - Thank you for the links. Great resources and have spent the last hour perusing the websites.