I've been working on building up the soil in the forest garden for a while now. I use a lot of organic material, either directly or composted around the trees and shrubs and it seems to be gradually building up the depth of the soil. About a year ago we took on a pair of rabbits from some friends. Free running rabbits don't really mix with growing a forest garden so they are in a run and they eat a lot of hay. The side effect is that I now have a regular supply of hay and straw and rabbit droppings to use as a mulch. This has really accelerated the depth of the mulch in the garden with nearly all the trees and bushes having a really good layer. I read that hay is a bad choice for mulch as it contains lots of seeds so it will be interesting to see what sprouts next year. I guess I should be ok as long as I continue to have a steady supply to put on top.
Not far from me is a iron age hill fort that I often visit. Most of it is bare grass banks but there is a good selection of yew trees and a few other varieties. Walking there just after New Year I was sad to see two of the yew trees blown down by the strong winds. It was interesting to see just how shallow the roots were though. Looking at the trees that are still standing shows just how tangled the surface roots are and made me think that perhaps they are much more stable when growing together with other yews close together. I wonder how growing a community of trees and other plants together in a forest garden might affect how susceptible they are to being blown over in high winds?