S07 - Session O4 - Housing humanity at the dawn of the 22nd century : living trees as a part of living buidings ?

Authors: Philippe Faucon *, Arnaud Fertet, Christophe Montil, Agathe Bombail

Although opposed for too long, plants are no longer the enemy of the city. Besides happiness provided by municipal green space, plants have multiple interests for cities. Indeed, plants can help manage rainwater, but also can reduce the urban heat island effect, thanks to evapotranspiration. Because of climate change, rains are expected to concentrate in severe episodes and temperature to grow as well as urban heat island effects, greener cities are needed. Plants can also enhance the living conditions, including health considerations. Besides green roof and living all, an original way to imagine these greener cities might be to think backward and build houses with living trees instead of putting plants around them. Moreover, the building consumes half of the resources extracted from the earth each year. However, trees are not supposed to have a house-like shape, so it is needed to give them this shape and to create in front of the wall a biological network, that give strengthness to the system. To do so, assembling living trees through anastomosis is the way that we choose to investigate. In March 2021, in our experimental greenhouse located in Rochefort/Mer (France), we initiated an experiment to study the anastomosis in five species: Acer platanoides, Celtis australis , Cornus Mas , Corylus colurna and Pyrus communis . This experimentation consists of testing two types of contact (parallel or perpendicular) between two trees from the same species with scraped bark, or not, maintained by diverse tools (screw, fishing line, buddy tape and flexi plant tie). From this, we get interesting anastomosis results. Indeed, on the 60 tests that we set, a third of them showed anastomosis before winter of 2021, mostly parallel one maintained with buddy tape. In the long run, with trees accepting multiple anastomosis with multiple congeners, we could delimit square shapes with living trees that can be the bases of houses. For that, we need to increase our knowledge (wich species ? young or older wood tissues ? how to characterize the success of anastomose), and working out on the way to produce this system and to set up them during building operation.