Tree shaping
Tree shaping uses living trees and other woody plants as the medium to create structures and art. There are a few different methods used by the various artists to shape their trees, which share a common heritage with other artistic horticultural and agricultural practices, such as pleaching, bonsai, espalier, and topiary, and employing some similar techniques. Most artists use grafting to deliberately induce the inosculation of living trunks, branches, and roots, into artistic designs or functional structures.
Tree shaping has been practiced for at least several hundred years, as demonstrated by the living root bridges built and maintained by the Khasi people of India. Early 20th-century practitioners and artisans included banker John Krubsack, Axel Erlandson with his Tree Circus, and landscape engineer Arthur Wiechula. Several contemporary designers also produce tree-shaping projects.
History
Some species of trees exhibit a botanical phenomenon known as inosculation ; whether among parts of a single tree or between two or more individual specimens of the same species. Trees exhibiting this behavior are called inosculate trees.The living root bridges of Cherrapunji, Laitkynsew, and Nongriat, in the present-day Meghalaya state of northeast India are examples of tree shaping. These suspension bridges are handmade from the aerial roots of living banyan fig trees, such as the rubber tree. The pliable tree roots are gradually shaped to grow across a gap, weaving in sticks, stones, and other inclusions, until they take root on the other side. This process can take up to fifteen years to complete. There are specimens spanning over 100 feet, some can hold up to the weight of 50 people. The useful lifespan of the bridges, once complete, is thought to be 500–600 years. They are naturally self-renewing and self-strengthening as the component roots grow thicker.
Living trees were used to create garden houses in the Middle East, a practice which later spread to Europe. In Cobham, Kent there are accounts of a three-story house that could hold 50 people.
Pleaching is a technique used in the very old horticultural practice of hedge laying. Pleaching consists of first plashing living branches and twigs and then weaving them together to promote their inosculation. It is most commonly used to train trees into raised hedges, though other shapes are easily developed. Useful implementations include fences, lattices, roofs, and walls. Some of the outcomes of pleaching can be considered an early form of what is known today as tree shaping. In an early, labor-intensive, practical use of pleaching in medieval Europe, trees were installed in the ground in parallel hedgerow lines or quincunx patterns, then shaped by trimming to form a flat-plane grid above ground level. When the trees' branches in this grid met those of neighboring trees, they were grafted together. Once the network of joints were of substantial size, builders laid planks across the grid, upon which they built huts to live in, thus keeping the human settlement safe in times of annual flooding. Wooden dancing platforms were also built and the living tree branch grid bore the weight of the platform and dancers.
Methods
There are a few different methods of shaping trees. There is aeroponic culture, instant tree shaping and gradual tree shaping.Aeroponic culture uses aeroponics, a process of growing tree roots in a nutrient rich mist. Once the roots are of a desired length for the pre-determined design they are shaped as they are planted. This technique may be used in part to help form large permanent structures, such as eco-architecture.
The oldest known root shaping are the living root bridges built by the ancient War-Khasi people of the Cherrapunjee region in India.
File:Arborsculpture bench.png|thumb|Living red alder bench by Richard Reames
Instant tree shaping is a method that uses flexible thin trees 2 to 4 m. The trees are bent and woven into different designs and held until cast. Bends are then held in place for several years until their form is permanently cast. With this method it is possible to perform initial bending and grafting on a project in an hour, as with Peace in Cherry by Richard Reames.
Girdling, also called ring-barking, may be employed to help balance a design should one part of the design outgrow the other, creating a loss of symmetry. Creasing is performed by folding trees such as willow and poplar over upon themselves without breaking.
Gradual tree shaping starts with designing and framing. Young seedlings or saplings 3–12 in. long are planted. The growth is guided along predetermined design pathways; this may be a wooden jig or a complex wire design. The shaping zone is a small area just behind the growing tip that forms the final shape.
This zone requires day to day or weekly guiding of the new growth. To achieve a finished piece takes longer with this method. A chair design might take 8 to 10 years to reach maturity. Some of Axel Erlandson's trees took 40 years to assume their finished shapes.
Common techniques
Some techniques are common to all the above methods though sometimes they are used differently for each.Framing might consist of a combination or any one of several materials, including the tree itself, living or dead.
Grafting is a commonly employed technique that exploits the natural biological process of inosculation. A branch is cut and held in place, it can be of the same plant or another cultivar of the plant. Grafting is applied to create permanent connections and joints.
Pruning can be used to balance a design by controlling and directing growth into a desired shape.
Timing is used as part of the construction and is intrinsic to achieving this art form.
Structure
Living grown structures have a number of structural mechanical advantages over those constructed of lumber and are more resistant to decay. While there are some decay organisms that can rot live wood from the outside, and though living trees can carry decayed and decaying heartwood inside them; in general, living trees decay from the inside out and dead wood decays from the outside in. Living wood tissue, particularly sapwood, wields a very potent defense against decay from either direction, known as compartmentalization. This protection applies to living trees only and varies among species.Growing structures is not as easy as it would seem. Quick growing willows have been used to grow building structures, they provide support or protection. A young group of German architects are in the process of such a structure and they are continually monitored and checked. Once the trees are of age to be able to take on load-bearing weight they are tested for stability and strength by a structural engineer. Once this is approved the supporting framework is removed. Projects are limited to the trees' weight loading ability and growth. This is being studied and the load capacity will be proved by testing on prototypes.
Design options
Designs may include abstract, symbolic, or functional elements. Some shapes crafted and grown are purely artistic; perhaps cubes, circles, or letters of an alphabet, while other designs might yield any of a wide variety of useful shapes, such as clothes hangers, laundry and wastepaper bins, ladders, furniture, tools, and tool handles. Eye-catching structures such as living fences and jungle gyms can also be grown, and even large architectural designs such as live archways, domes, gazebos, tunnels, and theoretically entire homes are possible with careful planning, planting, and culturing over time. The Human Ecology Design team at the Massachusetts Institute of Technology is designing homes that can be grown from native trees in a variety of climates.Suitable trees are installed according to design specifications and then cultured over time into intended structures. Some designs may use only living, growing wood to form the structures, while others might also incorporate inclusions such as glass, mirror, steel and stone, any of which might be used either as either structural or aesthetic elements. Inclusions can be positioned in a project as it is grown and, depending on the design, may either be removed when no longer needed for support or left in place to become fixed inclusions in the growing tissue.
The befit of using trees to grow a design which is then harvested for furniture, is that these pieces are stronger than the results of conventional manufacturing process. As the grain of the timber flows through the design instead of being chopped into smaller pieces then glued back together to form the design. All the joins of a shaped tree are grafted forming a stronger bond than a manufactured piece.
Environmental benefits
Shaped tree projects can play a role in mitigating the imbalance of carbon dioxide-oxygen that happens in cities, creating a microclimate that could be soothing to human habitation. The types of projects that could work in this environment would be playground equipment, road furniture, walkways with over-bridges and bus shelters. This increased growth of trees would improve the shade and create a fresh wind channel. When choosing the trees to use a fruit tree would have the added use of giving food as well. It can be renewable in the long run and when they die they can be used as fertilizer.The trees and shaped roots can hold the soil preventing soil erosion and forestalling landslides. In the right circumstances the trees could be planted over landfills and garbage dumps. Biodegradable waste could be used to help the trees remain healthily.