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Saturday, September 4, 2010

Elements of a food forest

Elements a food forest
A food forest is an increasingly common term that has taken hold in alternative gardening circles, however it describes a very old concept. It describes complex Agro-forests, forests created by humans, intentionally, primarily for satisfying human needs, which approximate the structure and function of a natural forest.

The formal study of these systems is relatively new even though examples of traditional food forests are found throughout the Americas, Africa, South and East Asia and the pacific. Each one has its own structure and species composition dependent on local ecological conditions, tastes and availability of planting materials.

Food forests have a multifaceted value to environment and society, their strength lies in their ability to sustainably protect the land, while also providing multiple nutritional and economic options for the owner with very low input level of materials and labour. Food forests are also not just about food, they also provide Shelter, Fuel, medicine, forage and game. They can provide Aromatic oils and resins, timber and craft goods for sale. They also provide a range of ecosystem services such as soaking up nutrient and microbial pollution, retaining and building stable soils, humidifying, rehydrating and cooling landscapes. They have great conservation value in their ability to provide habitat for many wild and semi wild species, especially birds,most especially when they provide islands of sanctuary in a sea of fields or farms.

They also create a very livable landscape mosaic when interspersed with wetlands and grasslands. As a species we enjoy a wide variety of foodstuffs and goods that are found in multiple habitat types so it is useful for us to live on the edges of 2 or more habitats. One of the most habitable areas of all is near these anthropogenic food forests.

Establishing a piece of viable human habitat is not a difficult thing. You are already doing it when you live on a piece of land and return any domestic waste to the site.As in amongst what we call waste are seeds and other propagules just waiting for an opportunity, waiting to be left in a rubbish pile where they may find enriched soil conditions and germinate. Many of these plants are dispersed by large animals in their wild habitat. Animals eat the fruit along with other fruit and herbage and deposit neat piles of fecal micro-enrichment far from the parent tree. Our relatives, the great apes, are major seed dispersal agents and probably played a role in the selection and evolution of the tasty fruits across Asia and Africa today, some biologists suspect that the reason for the lack of tasty tropical fruits in Australian rainforests is a lack of primates.

With the selective force of many animals flocking to a particular tasty tree, and then spreading its progeny all through the forest in radiating seed shadows, repeated year after year, generation after generation it is not surprising that fruits have been fashioned to be bright, colourful large and sweet, just like Primates prefer. Our closest relatives, the chimpanzees, have been studied for their effects on seed dispersal in their native habitat. Some seeds are swallowed whole, and deposited later, while others are suck free of pulp and the remaining Wadge, a compressed lump of skin, fibre, pulp and seed (Goodall 1986), is dropped or hurled back into the forest. Studies on the germination rates of seeds from these Wadge parcels showed germination and survival rates greater or equal to defecated seed, and much higher than seed in fruit left close to the parent tree. Think about that next time you are spitting pips from a Watermelon or Mandarin! We are not so different.
Humans don’t swallow so many fruit seeds anymore, we even specialize in breeding fruit with fewer or no seeds! And when we do eat seeds, unavoidably, we flush them to sea or bury them in great underground anaerobic vats (Septic tanks).What we do, increasingly, is compost. Composting is a sanitary means of disposing of all manner of organic wastes and recycling them back into soil food. In theory thermocomposting sees the materials auto-generate heat as the microbes metabolize foodstuffs, this activity raises the temperature up above 60C and self pasteurizes the pile. It basically cooks any pathogens, insects, seeds and other items and renders the mix unattractive to vermin. The heat kills many seeds and this is the kind of compost you would put on your annual garden beds. The other more common compost, often by neglect more than intention, is more of a repository bin for scraps. They are better covered above to exclude vermin, but open to the earth below to allow free movement of earthworms, slaters and other benign decomposers to and from the pile. It is in these piles that we might throw fruit pulp and pits, non weedy leaf and trim, gnawed dog bones, ash from a barbecue or fireplace, and all sorts of other things that don’t attract flies, or bears!This enrichment supplements the natural succession of the area around Human by concentrating plant nutrients, and by seeding directly with our preferred fruits!
This system has been going on for millennia. This kind of open backyard tip where the chooks and the dogs eat the scraps and all thats left ends up in a big old heap may be as old as gardening itself. Studies on plant domestication suggest that these midden gardens were important sites for domestication of tree crops. Bringing seeds from distant places and discarding the seeds in fertile ground created opportunities for hybridization of distant relatives. This process continues today especially among people living adjacent to forests and harvesting wild foods. Building a food forest involves tickling the systems of forest repair by first understanding and observing what happens when we do nothing.
Weeds will blow in, grass will grow rank and be overtopped by weedy shrubs and legume trees. After a few years a low canopy may form and the edge of the new forest may be a tangle of vines, and shrubs with small bird dispersed fruits.
Under the establishing canopy partially shade tolerant bird dispersed species will sprout. These will shoot up and overtake the scrubby layer and form a higher canopy. They will fruit and in turn attract more birds which will take and deposit more seed.
In time perhaps larger wildlife will bring in large seeded species that are quite shade tolerant, these will slowly establish and wait for a small gap in the canopy to make a push for dominance.
We can do this too, the difference being control and speed. Control of species composition, control of speed of formation, and control of lifespan before the forest is reopened to a new cycle of rebirth.
Of the thousands of species of direct use to people, and the thousands more that support desirable wildlife or play important roles in the ecosystem we can learn to select and build artificial forests of extremely high utility.
For ecosystem stability it is hypothesized that a mere 15 species is necessary to stabilize and ecosystem, however not all species are created equal in terms of importance. So it is important for use to understand the concept of functional groups within ecosystems if we desire to create them.
I’ll be focusing on some of these in separate articles as we go along, they will include Nitrogen fixing plants, Fungi, Decomposers, Plants that bio-accumulate minerals from deep in the soil strata, Pollinators, Grazers, Predators, Pathogens and Parasites, Weeds and Disturbers.
We have a lot of reading to do ourselves and I realize the terms used are not perhaps what ecologists use, however they are the functional groups we work with.

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