Photo credit: Avantgardens
Binding poles with willow cuttings to build a living tunnel
Building living tunnel greenhouses for rural people in the drylands
By Prof. Dr. Willem VAN COTTHEM – University of Ghent (Belgium)
One of the most serious problems for sustainably constructing greenhouses in the drylands is that of the strong winds, regularly destroying the greenhouse cover.
Most of the greenhouse constructions, e.g. those with a plastic (polyethylene) cover, can’t resist these winds and the recurrent need for reparation of the expensive UV-protected cover discourages those who see greenhouses as a valuable tool for sustainable economic development of the local people.
It is my sincere conviction that a good solution can be found in switching from man-made constructions with greenhouse frames (metal or bamboo) to “living greenhouses” with poles of growing trees.
In every single region on earth one can find (or introduce) easily rooting tree species. For some of them it suffices to directly planting cuttings in the local soil to get these cuttings rooting and developing after a rather short while. One of these species is the Chinese willow (Salix matsudana) of which a number of varieties are cultivated all over the world. For other tree species one can apply natural rooting hormone, e.g. the one extracted from willow (Salix) chips (see http://www.ehow.com/how_4824692_make-rooting-hormone.html).
Having in my garden in Belgium a couple of these willows, I thought that some cuttings could be used to “construct” a sustainable “teepee”. Within a very short period such a shady little tent was grown (see photo below).
A young teepee set up with branches of the Chinese willow (Salix matsudana) in Belgium.
The 3 meter long branches, used as teepee poles, soon developed numerous lateral branches, some of which were cut off and planted to produce new poles for a second, a third, a fourth, … teepee in the future.
People are building such a living teepee in their backyard as a shelter or playhouse for their children.
Playhouse teepee covered with beans or peas.
It goes without saying that cuttings (poles) can also be planted on two parallel lines, e.g. at a distance of 3-5 meter and over a length of 30-50 meter, with a pole every 50 cm. One can keep the poles growing into young trees, pruning them occasionally to form two sidewalls. Once the stems (and sidewalls) are high enough, one can bend the stems over and bind their tops to form a “living tunnel”. Lateral branches, growing outwards or inwards and reaching a length of e.g. 30-50 cm, are pruned. One can also “weave” the lateral branches in the plane of the sidewalls into a strong network.
Willow poles, forming a tunnel, will soon form new branches to create a shady space.
A newly built willow tunnel
Such a tunnel can be constructed all over the world with a number of local tree species or even with vines, e.g. grapes or flowering species like Wisteria.
The canopy of the tunnel is filtering the heavy sunlight. Inside the tunnel, air humidity is higher, due to the continuous transpiration by the leaves.
A living tunnel can be used as a nursery for the production of hundreds (if not thousands) of saplings, starting from cuttings, excellent material to set up more tunnels. But a tunnel can also be used as a shady kitchen garden in which numerous food crops can be grown in containers, e.g. in bottle towers (see http://youtu.be/-uDbjZ9roEQ), consuming less water than the volume of irrigation water normally used in open fields.
Thus, once a single living tunnel greenhouse is growing in a location, the subsequent construction of new tunnels is in fact unlimited. It suffices to make the right choice of a tree species, that is adapted to the local environmental conditions, easily rooting and developing relatively quickly.
The Chinese willow (Salix matsudana) is one of those species easily adapting to different types of climate. I got mine from Arizona and it is growing remarkably well in Belgium. One could even use the Navajo variety of this Chinese willow (Salix matsudana var. Navajo), a drought-resistant variety growing in desert-like circumstances, only needing a minimum of water. It would be encouraging to see some of these living tunnels created in a number of drylands, knowing that these would most certainly motivate many rural people to get one themselves.
Anyway, whatever the tree species chosen, we are quite sure that it must be feasible for all the people on earth, to set up their own “living teepee” or their “living tunnel greenhouse”. Imagine all the rural people in the drylands having such a tunnel close to their house, using it as a shady greenhouse in which they can grow fresh food or as a pleasant shelter for the hottest parts of the day. Sustainable development in its most beautiful form, contributing to the improvement of the living standards of the population.
The choice is theirs. Let us help them to become familiar with this affordable technique.
DESERTIFICATION 
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