Before Columbus arrived, the whole land mass that we now call America
could be crossed by an industrious squirrel just running from treetop to treetop. We've cut down most of those trees; nowadays that squirrel would have to try running across power lines. But there is something that anyone with even a small yard can do to help: plant a forest garden.
Forest gardening arose out of the agroforestry movement, which advocates using forest-style agriculture on small plots of land in order to get the most out of the space. Forest gardening takes this theory one step further, advocating the use of backyards and similar urban spaces in order to replenish the Earth's forest cover.
Deforestation in North America, and indeed the world, has been increasing at an alarming rate since the Industrial Revolution. 78 million acres of forest are cleared every year, without regard for old growth forests or, often, for reforestation.1 And of course, reforestation done by logging companies usually involves a thorough spraying of pesticides - a sure ecosystem killer.
Forest gardens are a small and important step towards replacing what is stripped away through most forms of logging. They are also a great way to get the most out of a piece of land. Conventional gardens are planned out on a low-lying horizontal plane and often include water-consuming plots of grass and separate flower gardens. In contrast, forest gardens are designed to include all seven layers found in naturally-occurring forests:
The "canopy" formed by the tops of the higher trees;
The planes of lower-growing trees such as dwarf fruits;
A shrub layer including bush fruits;
A herbaceous layer of herbs and vegetables;
A ground layer of plants like creeping thyme;
A vertical layer occupied by climbing berries and vines, which can be trained up the trees;
The "rhizosphere," a layer underground made up of shade-tolerant root-plants like potatoes.
Forest gardening uses plants that are specifically chosen to work well when planted together. For example, as in regular forests, the roots of certain trees travel deep into the subsoil and bring up water for the whole garden. Those trees also provide shelter for shade-tolerant plants.
The result of all these layers working together successfully is a garden that waters itself; self-pollinates; does not need to be weeded (because low ground cover prevents weeds and acts as mulch); fertilizes itself through legumes which add nitrogen to the soil; and which needs very little maintenance after the first two years. Like naturally-occurring forests, forest gardens are full of perennials and self-seeding herbs, fruits, and vegetables, and don't require any human watering, pest control, fertilizing, or weeding to make them thrive.
Successful forest gardens have been planted in many countries; the most well-known is probably Robert Hart's garden in Shropshire, which produces much more food than they can eat each year. More information on forest gardening may be found in his book on the subject, "The Forest Garden.2 Graham Burnett has also kindly created a website with pictures of the original forest garden, and Robert Hart's sketched plan for it.3