In a Forest Ecosystem, falling leaves - also known as leaf litter, twigs, logs, bird droppings, worm castings, animal droppings and urine, dying bugs, etc. mix with the existing soil to create new soil. Microbes and mycelia (the underground fungal networks that fruit at the surface as mushrooms) digest these materials and create soil which has structure and nutrients that support and promote plant growth. It takes hundreds of years.
When we make Compost, we're imitating how this works in a forest, a field, a prairie, a river valley or a meadow - but a forest in particular. Much of the world's farmland was created by forests - then the forests were cleared away - and farms, then later housing developments, were put in place of forests - leaving us with a need to create new soil.
Forests - with their rich density and diversity of plant and animal life - have been our greatest soil creators. Now in many ways it's our job - through reforesting, through composting and sheet mulching, through growing and turning nitrogen fixing plants and encouraging a diversity of plant and soil microbial life.
In Companion Planting, we place plants near each other that get along well, based on varying root heights and root density, chemicals the roots put out to defend against predatory insects, etc.
In a Forest Garden, we're imitating a natural Forest Ecosystem and using Companion Planting to use both vertical and horizontal space effectively.
A Forest Garden - which is also known as a Food Forest - imitates a natural forest's 7 vertical layers of plant types. To create a Forest Garden - which takes about 4 or 5 years to get going in earnest - start by planting an orchard at normally accepted intervals between trees. There's the top layer, layer 1 going top down, the canopy layer. Next, layer 2, are dwarf trees, which hold fruit well because there is a nice ratio of plant weight to branch size. Next is layer 3 - fruiting shrubs (in simplest terms shrubs are like trees but smaller). Then layer 4, the herbaceous layer - non-woody plants. Next down, layer 5, the root plants aka the rhizosphere. Now we're down to layer 6, the ground cover. Now it's layer 7, vines and creepers and climbers.
Forest Gardens don't require weeding - just lots of mulching - and a lot of clipping - and a bit of pruning. Sheet mulching - the creation of topsoil by encouraging mulch, which would decompose into a soil in a few years on its own anyway, to become soil more richly and more quickly by using multiple layers, is material for another blog.(Photo of Robert Hart by Fransje de Waard ... with the few tools he used to maintain his Forest Garden)
If you'd like to learn more, Patrick Whitefield is a fine writer whose work can be understood by people new to Forest Gardening or experienced, and How to Make a Forest Garden is based in part on conversations Whitefield had with Robert Hart. You can also visit Youtube for a video featuring Robert Hart describing how Forest Gardening works.
