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The Layers of a Forest & the Importance of Leguminous Plants in Forest Re-Growth

By Joshua Muir

‘An edible forest garden is a perennial polyculture of multipurpose plants; It’s an edible ecosystem, a consciously

designed community of mutually beneficial plants and animals intended for human food production and consumption.’

– Dave Jacke, Edible Forest Gardens Vol.1

‘Managed sustainably, a healthy forest can be become a perpetual resource, one that provides for many of our basic needs. At the same time, the forest is a living ecosystem: sheltering and feeding wild creatures, conserving water

and nutrients, and modifying climate on both the local and planetary level’ - Robert Hart

When we think of a forest, a landscaped over grown with trees & plants comes to mind. The Aborigines of Australia couldn’t see the forest from the trees, for them, the forest itself was one entity including the animals. The animals were seen to be the highest expression of the forest. Forest Gardening categorizes the system not according to species but to layers of the forest. A forest has many, many layers. I probably won’t list them all here, but a typical forest gardener mentions:

1. The ground cover (pioneer plants, grasses, etc) 2. Small Vegetation (Wild Vegetables, Small Annuals with no wood) 3. Shrub layer (A woody, hardy layer about 1m or less) 4. Large Shrubs 5. Understory trees (fruit trees, young trees) 6. Canopy (Trees that are the tallest) 7. Root layer 8. Fungi (grown in moist, damp regions, likes old wood) 9. Vines/Climbers 10. (and in the subtropics/tropics) Emergent Species (Palms e.g. coconuts) 11. Ferns 12. Epiphytes (plants that grow on tree trunks)

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And on top of that we could name many more, like animals, soil, potential aquaculture products if there was a pond. If we can mimic natures systems successfully then our garden will be over-yielding. It won’t just yield a single crop – it was have countless. And that in turn is the appeal and reason why we would want to forest garden even typical organic gardening techniques. Oh, and the fact that if the majority of the plants in the system are perennials (grow for more than 2 seasons) which means they will self-seed & fertilize – and the forest will take care of itself. 0 input, endless output – whereas monoculture/horticulture is endless input, minimal output. So as designers mimicking this pattern, our first question about our site should really be, how do I turn my piece of land into a forest garden? And to know that, we must know how nature takes a piece of bare land and develops the site into a forest. If we take the example of a site with damaged soil, in nature, the first thing we see growing are thorny, prickly, nasty weeds. Simply, this is nature’s way of warning all to stay off the land, as the mother is mending herself. Over time other weeds will compete and grow, leading to shrubs peppering the landscape, to trees, etc. Nature can take decades to develop a forest at full maturity. So how can this process be quickened? Permaculture design allows us to step in, and add elements to assist nature that will ensure a forest garden in 10 years or less. First of all is to ensure that on our land, that our soil is never left bare. So if it is bear, we would cover one acre with thousands of ground cover seeds to ensure that not one piece of soil is left exposed. And the type of ground cover does matter.

Leguminous Plants Leguminous Plants add nitrogen to our soil, an essential natural chemical for building balanced soil. Nitrogen is plentiful airborne, legumes absorb nitrogen through their leaves, storing it in their roots. A type of bacteria in the soil feed on nitrogen, and the plant actually allows the bacteria to beneficially infect the plant roots in exchange for minerals and nutrients. There are many leguminous varieties, of trees, shrubs, cover crops – for every environment. We can also add manure or green manure in our system as mulch or fertilizer which would add nitrogen, but having leguminous trees allows the system to main itself.

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Back to our example of bare land: our cover crop is a leguminous variety. In bullet point format, the steps of rejuvenating land is as follows:

1. Spread mulch over land as best as possible, the more the merrier. 2. Scatter thousands of the legume cover crop over the mulch. 3. At the same time, plant all leguminous:

i. Small shrubs (1000) ii. Medium shrubs (500)

iii. Understory (100) iv. Canopy (20) v. Vines/Climbers

etc. follow the list on page one of the layers of a forest. 4. Water generously the whole system

We do have to take care of the system initially. After the first season, the cover crop will have completely grown, seeded, and died. Slowly the landscape starts to shape itself. Then, after the first year, we come into the land and thin out most of the shrubs, leaving 100. A year later we thin out the medium shrubs, leaving 50. The understory later we too thin out several years later, leaving 20. And we leave maybe 5 or 10 of the Canopy trees. This is around the seven year mark. The trick here is when to thin out the plants – when precipitation is greater then evaporation. Or perhaps just before to ensure that there is water for the plants to grow. The chopped trees will start to break down quickly and go back into the system. Another amazing thing that happens here is that when you chop of a branch of a plant, even down to its base, as soon as you do that the roots drop off the same proportion of roots as the shape of the plant is usually similar to the root structure. When the roots drop off, more nitrogen becomes available for the plants in the soil. And some of the plants will coppice & pollard, that is, cutting back a plant (either its trunks or again, down to its base), and once cut, start to reshoot from the cut. In turn, you cut these back, and more nitrogen gets released into the soil. But the best thing about this system that makes it genius is at the same time as all this is going on, you’ve already planted your fruiting trees and plants (& dynamic accumulators which will be discussed shortly). So whilst you are thinning out the forest, the room for your bananas, apples, grapefruits, chocolate pudding fruit all greatly increases & the soil is far more fertile. Wild vegetables, herbs, medicinal plants would all happily grow in the young forest biome. So this means, you can take a completely bare plot and in several years grow an over-yielding over-abundant polyculture that would feed, many people. At an estimate, on acre could easily feed 15 people a balanced diet. As an example of this, a man in the backyard of his home in Melbourne grew over 270 varieties of plants and fed his family of 4, entirely, for a year. This design pattern (of mimicking a forest garden) is truly the most efficient agriculture system established.1

1 Read more upon agro-forestry for more information upon the actual yield statistics – always, they exceed modern agriculture’s yield by a long-shot.

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A quick word on dynamic accumulators. These plants are have a unique root structure, known as a tap root. A tap root burrows straight down narrow and deep, much more than other plants. From here it mines beneficial trace minerals for its own use back up the root to the foliage. Once the foliage drops or the plant dies, all the trace minerals are available for other plants to absorb. Dynamic accumulators greatly improve the mineral content of the soil and should also be widely spread along with leguminous plants. They typically are small annuals but there may be larger shrubs etc available. The diagram to the right shows varied root systems. Pests are never mentioned, the ecosystem balances itself as biodiversity equals greater health. Disease, too, is never an issue. Again, a garden that has hundreds if not thousands of varieties of plants would have its own defense againt such problems. It’s worth expanding on this point here for many reasons:

1. First & foremost, pests are not negative issue in a forest garden as they will be filling a niche in our space. Most insects are prey for our beneficial friends, like dragonflies, so if there is a small population of aphids, for example, they would be providing a food source for something which is a genuine benefit to the ecosystem. Thus, pests have a function and are a necessary component.

2. Zero finance would be spent on herbicides, pesticides, fungicides, or other deterring techniques. And that is the biggest expense of a farm – the non-renewable resources. Of course, that extends to electricity, seeds, etc. as well, and the ‘cides’ are a great percent of this category. Figures quote as much of 90% of spending goes to these inputs, so whilst the gross profit of a farm could be 50,000, for example, the net income would only be 5,000 in total. If you could rid of most of the operating costs of a farm through bio-diversity, then you gain thousands of dollars.

The creation of a forest garden can be achieved in a time frame of around seven years and would, theoretically last hundreds, if not thousands or years. Once the eco-system starts to mature, it will become self-sustaining so that there is a zero-maintenance over-yielding system. One acre could feed families, and provide other resources (like gas or building wood) from the forest – which would be endlessly more productive and financially viable then an organic, horticulture farm. Maybe once every few years someone would need to come through and thin out the forest. Maybe. That would take 2 people a few hours for maintain a system that would last a long time. If the system was going to be heavily used and many inputs were to be put back in, like vermipost, organic matter, chickens fertilizing the ground, the garden would produce even more. This system gives far more out then other systems with minimal input, on a sliding scale. In Geoff Lawton’s video Establishing a Food Forest the Permaculture Way, much of which the above theory of this article was based upon, he visits an old system on the Permaculture Research Institute’s land in Australia which had been untouched for years. And what did he find? Tropical fruit in abundance, healthy, dark soils, animals – and nobody has maintained the system in years. It was in need of some care however nothing that was too strenuous, and the fact that the forest has been continuously providing after many years of human intervention nulls the effort needed to maintain the system.

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This system can be downgraded to small scale system – or to an even broader scale. It may sound like fantasy, but the creation of such environment in both countryside and urban landscapes is possible, has been done, and many permaculture designers around the globe currently making food forests are reality.2 Creation of a sustainable abundant food forest is truly the permanent agriculture for the future, and for the present. The techniques are tried & tested, so it is now our duty as guardians of Mother Gaia to implent these self-perpetuating systems for the future of our food, economic, and financial security.

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2 Further reading on the establishment of forest gardens can be found in Dave Jacke & Eric Toensmeier encyclopedic books Edible Forest Gardens Vol 1. & 2. For anybody wishing for more practical design techniques, theory, and in-depth temperate planting guides – this is the most well-researched and published book available. 3 Bill Mollison, Permaculture: A Designers Manual, pg 140.