Just dropping in quickly to point out that food forests (or forest gardens) in cold temperate climates rarely look as dense and saturated as in the tropics. They still work and work very well, just the spacing must be tweaked to allow for a vastly different solar regime.

A simple example is using strawberries as a ground cover plant. In the first years, you will get an yield of fruit, but with the closing of the canopy and development of the shrub layer, all you get is a ground cover. If you want those strawberries, you'll have to replant them (or encourage them to grow) on a sunny edge of the system.

Graham and Nancy Bell's food forest in the UK is a nice example. Maddy & Tim Harland's too comes to mind.