Autor(es):
Palma, J.H.N. 
; Crous-Duran, J. ; Merouani, H. ; Paulo, J.A. ; Tomé, M.
Data: 2014
Identificador Persistente: http://hdl.handle.net/10400.5/7261
Origem: Repositório da UTL
Assunto(s): tree plantation; design; agroforestry
Descrição
Poster Most of forestry or agroforestry artificial plantations either have an orthogonal design, or curvilinear under contour lines to prevent soil erosion. These designs are known to maximize machinery workflow or erosion control respectively.
As in many occasions in land use management, what optimizes machinery operation is not what optimizes prevention of soil loss and vice versa.
An alternative and intermediate design system such as an Archimedes spiral could offer in one hand, the ability to have equidistant lines to facilitate machinery operation and, in other hand reduce soil loss in comparison to orthogonal designs. Additionally can be an alternative design when aesthetics plays a role in the planting decision.
Although the spiral land use design is present in permaculture related literature, scaling up the methodology to forestry is practically absent in literature. This work tries to contribute to the knowledge of planting trees in an Archimedes spiral design.
Making a spiral is a trivial command in computer assisted design, but this work envisaged the creation of the spiral in the field without any high technology software (e.g. tractor with laser technology) to enlarge the scope of possible application.
We used the spiral equation to explore and define in the spiral: 1) the number of turns, 2) the distance between the arms and 3) the tree density. The widest machinery of the farmer was five meters so, to allow the tractor to move inwards and outwards in the spiral, we opted to design twelve meters between rows to allow 1 meter safety distance to the tree line. The final spiral would have three arms with two meters between trees in the line (240 trees). Part of the challenge was to implement the spiral with the exact dimensions in order to respect the farmer needs.
To implement the spiral in the field a “field spiralographer†was made with the following description: an axis with about 1 meter high, where on top was placed a base with six equidistant arms. Each arm was made telescopic to allow different lengths of the arms. At 2 meters from the center the arms were marked and a screw pin was placed on the mark. A rope was rolled up around the screw pins. The number of complete turns is equal to the number of lines existing in the field spiral. Because the union of the screw pins in the arms’ builds a hexagon with 6 x 2 meters perimeter, a full turn has 12 meters length. To mark the spiral in the field, start unrolling the rope and walk at the same time avoiding a loose rope, marking the place for planting the trees. By the end of a full turn around the “spiralographer†there should be 12 meters distance between the first and last tree mark. By keeping unrolling the rope until needed, the spiral keeps being designed in the field depending on the turns needed.
In other words, the “spiralographer†could be an hexagon with R radius, being 6xR, the distance between the lines in the spiral. Unrolling and keeping the rope unloose will provide a guide to mark the spiral in the field. Because the description might be unclear, a video was made showing the “making of†this spiral preparation: http://www.youtube.com/watch?v=5lzjT1UcJvM
The experimental site is being used to survey operational costs to compare with conventional designs.
