A week or so ago I ordered Patrick Whitefield's "How to Make a Forest Garden" and have been reading it now for the past couple of days. It's an excellent book which serves as both an introduction to the concept of forest gardening as well as a detailed explanation for those that are ready to get their hands in the soil. While forest gardening is not technically permaculture it can be an excellent component in a larger permaculture design which is how I am planning to use it.
To put it simply, forest gardening uses fruit trees as the base in a layered design modeled after forest or woodland ecosystems. The fruit trees serve as the canopy with other layers of food such as soft fruit bushes such as Gooseberry which comprise the shrub layer and then an herbaceous layer of perennial herbs and vegetables. Annuals can be used but forest gardening places great importance on using perennials. By modeling our forest garden on nature we will see a variety of benefits such as less work (once the system is initially established) and more over-all production of a greater diversity of food in a smaller space thanks to the more efficient use of vertical space and time.
Think of it as an fruit orchard with a bonus. Rather than just apples, peaches, plums and pears why not also grow gooseberries, blueberries, currants, juneberry, ligonberry, pawpaw, and even kiwi all in the same space using a layered approach? Add to that a variety of herbs, perennial and annual vegetables along the outer edges and your orchard is now far more interesting, productive and less work. Less work? Yup. Remember an orchard either has lots of grass which is often cut and mulched to keep it from competing with the fruit trees. The forest garden's layers of berries and vegetables not only provide food but they help to mulch by shading out the grass. You may still need to mulch a bit but it should be significantly less than if you were just growing the fruit trees by themselves.