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Forest Gardens

The Agro-Forestry Research Trust, Devon, UK, 2010

What is a Forest Garden?

Forest gardens are designed productive systems which mimic the ecology of forests to give yields which include fruits, nuts, wood material, craft materials (e.g. dyes), vegetables, herbs, flowers, and mushrooms. Forest gardening has a long history in tropical cultures, but in Northern Europe the principles have only been utilised within the ancient tradition of managed foraging in natural woodland, and old forms of orchard growing – which up until the 20th century involved combinations of fruit trees, bushes and vegetables. The idea of whole system forest gardens planted from scratch was pioneered and popularised in England by Robert Hart in the 1990s; it is still being researched and developed by Martin Crawford at the Agro-Forestry Reserach Trust, and Ken Fern from Plants for a Future, among others. This system needs development for European countries since the traditions and principles used, say in South America, may adapt well for parts of Australia, but Europe faces a different growing context from season length to range of species for each niche.  Tropical food forests can be dense and highly productive since high temperatures and stable light conditions enable many species to be productive in shade. European forest gardens, however, are based on the ecological relationships of woodland edge habitat since most of the native understorey plants need lighter conditions to fruit. The productive woodland edge has a south-facing aspect, a natural windbreak and mild micro-climate. This means that any new forest garden must provide some southerly exposure and protection from strong winds before plant choices can be made.

Structure

Designs of ‘food forests’ or ‘forest gardens’ use seven levels of plants mixed in polycultures or guilds. The seven layers refer to the storeys of vegetation:

  1. canopy trees (e.g. large fruit/nut or nitrogen-fixing trees)
  2. understorey trees (e.g. small fruit trees)
  3. shrub layer (e.g. blackcurrant bush)
  4. herbaceous layer (e.g. comfrey)
  5. ground layer (e.g. strawberries)
  6. rhizosphere (e.g. root vegetables, fungi)
  7. vertical layer (e.g. climbers, vines)

The 7 Levels – by Robert Hart

It is important to note that layout or combinations of plants also relates to the nature of their roots. Different plants have different root profiles, some have deep tap-roots, and others have shallow, spreading root systems. Combining plants with different root systems also ensures that the permaculture concept of stacking (either in height or time) can be extended to depth, maximising the soil space. Root profiles are amazing things – what we pull up and see is only a fraction of what a plant has below the surface since the finer roots are left behind.

Fertility

Plant choice also affects the self-sustaining fertility of a forest garden system. Some plants are included to be productive for other plants, rather than the human directly. This is one example of the permaculture principle of letting nature do the work. Plants such as comfrey (Symphytum officinale) and dandelion (Taraxacum officinale) accumulate higher levels of certain nutrients and minerals than others – plants with long tap-roots can often reach another soil layer to access minerals unavailable to others. When these plants die back, or their leaves are harvested and used as mulch, they decompose and make nutrients available to its neighbours via the chemistry of the topsoil. Nitrogenating plants such as legumes are included in the planting scheme – in the form of herbaceous perennials, shrubs, or even trees, depending on the space available. The nitrogen is produced in special root nodules where a specialised bacteria (rhizobia) fixes nitrogen for the plant in exchange for a home, water and dinner. Other sources of fertiliser can be planned-into the forest garden system such as human urine, composted humanure, or increased animal waste entering the system naturally (such as birds moving in to newly canopied area), or an autumn application of raw horse manure.

Maintenance

The forest garden is no-dig after establishment, unless new areas are developed or roots are harvested. Weeding is a matter of controlling unwanted plants and/or keeping productive plants within their areas if necessary. Plant matter is returned to the soil in the ‘chop and drop’ style – there is no compost bin. In this way the decomposing matter returns the fertility to the soil while acting as mulch and providing a home to many more living organisms and processes than a compost heap. It is also not watered artificially, although this can be arranged in special designs in dry areas where rainwater harvesting can be utilised. The established root systems, non-compacted soil, and natural mulch layer help protect the planting from all but the most dramatic weather. Other management techniques include summer pruning of trees to mimic wild grazers, and splitting perennial plants in the autumn when they are overcrowded to maintain productivity. A forest garden design is usually low maintenance, using naturalistic planting styles, with harvesting being the most time-consuming activity when the system becomes established – this will take 3-10+ years depending on tree species used, site choice, and experience.

New Ways of Thinking

Knowing the timescales involved is key to the successful application of a forest garden. It provides a useful life-lesson in understanding the realities of the natural systems around us, their development or recovery times, and our responsibility to plan for a productive future. It also avoids unrealistic expectations and creates awareness of more ways to mimic nature, such as using succession planting (temporary plantings over a season or a few years) for extra productivity while slow-growing trees or shrubs mature. Very often, traditional and nearly forgotten agroforestry ideas can be applied to a forest garden system whether small or large-scale, so the all important research phase can take you from ‘Gardener’s World’ to ‘The Gutenberg Project’ through everything from cultural history to ecology. It is much more than a way to combine an few trees, bushes and herbs – it’s a systems-thinking revelation. Many community gardens are now picking up on this planting approach, via permaculture, to provide a wider range of harvest and a richer plant environment for local people and native fauna. The passive and active opportunities for environmental awareness and food education are implicit in a good food forest design. In all cases, a forest garden is an investment in the future, and brings an added incentive to plant much needed trees.

Websites:

1. Agroforestry Research Trust: www.agroforestry.co.uk/forgndg.html

2. Edible Forest Gardens: www.edibleforestgardens.com

3. Lydford Forest Gardens: www.lydford-forest-gardens.com

4. Self-Willed Land: www.self-willed-land.org.uk/permaculture/forest_garden.htm

7. Interview between Rob Hopkins and Martin Crawford of Agroforestry Research Trust: transitionculture.org/2011/06/27/cereals-agroforestry-and-drought…

8. Blog on a forest garden in Aberdeen, Scotland: scottishforestgarden.wordpress.com

Books:

  1. Crawford, M., 2010. Creating a Forest Garden: Working with Nature to Grow Edible Crops. White River Junction: Chelsea Green Publishing.
  2. Jackie, D. and Toensmeier, E., 2006. Edible Forest Gardens Volume I: Ecological Vision and Theory for Temperate Climate Permaculture. Vermont: Chelsea Green Publishing.
  3. Jackie, D. and Toensmeier, E., 2006. Edible Forest Gardens Volume II Ecological Design and Practice for Temperate Climate Permaculture. White River Junction: Chelsea Green Publishing. 4.
  4. Whitefield, P., 2000. How to make a forest garden. East Meon, Hampshire: Permanent Publications.
  5. Hart, R., 1996. Forest gardening: cultivating an edible landscape. White River Junction: Chelsea Green Publishing.
  6. Hart, R. 1996., Beyond the Forest Garden. London: Gaia Books.
  7. Douglas, J. S. and Hart, R., 1984. Forest farming: towards a solution to problems of world hunger and conservation. Intermediate Technology Publications.
  8. Smith, J.R., 1987. Tree crops: a permanent agriculture. Washington, D.C.: Island Press.
  9. Fern, K., 2000. Plants for a future: edible & useful plants for a healthier world. East Meon, Hampshire: Permanent Publications.
  10. Law, B., 2001. The Woodland Way. East Meon, Hampshire: Permanent Publications.
  11. Law, B., The Woodland Year. East Meon, Hampshire: Permanent Publications.

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