Living bridges using aerial roots of ficus elastica – an interdisciplinary perspective

Abstract

Here we report on a pilot study of the Living Root Bridges (LRBs) in the Indian State Meghalaya, which are grown with aerial roots of Ficus elastica , a facultative hemiepiphyte developing abundant aerial roots. Locals use these aerial roots to build living bridges, which strengthen themselves over time due to adaptive secondary growth and their capacity to form a mechanically stable structure via inosculations. An extensive inventory of LRBs in Meghalaya including data of location, altitude, approximate age and bridge length was performed in field studies. Root morphology was characterised by measurements of cross-sectional area and shape-related parameters and analysed in relation to the orientation of the roots. LRBs are found to occur mainly in the mountainous limestone rainforests where F. elastica may be native or traditionally cultivated. They cover an altitude range of 57–1211 m a.m.s.l. and display a length of 2 to 52.7 m. Some bridges are several hundreds of years old. Horizontally and vertically trained roots differ significantly in shape and cross-sectional area when approximately even-aged roots are compared. The results are discussed from an interdisciplinary perspective, considering the adaptive traits in the natural life cycle of F. elastica and possible applications in living architecture (Baubotanik).

From dangerous branches to urban banyan: Facilitating aerial root growth of Ficus rubiginosa

“…Aside from the intellectual interest of this question, it is important because the amount of structural support that the roots provide will depend on the anatomy of the roots. There are already hints that the aerial roots of Ficus can have substantial mechanical strength–for example, the aerial roots of Ficus elastica can be trained to form living bridges that span more than 50m [16].…”

“…Despite the benefits of branches being supported by aerial roots, there is very little published literature on how to encourage and accelerate aerial root growth. There are well-established techniques in parts of India whereby Ficus elastica aerial roots are trained around bamboo or wood to form spectacular living bridges that can span more than 50m [16]. However, it is not clear whether winding roots around support structures accelerates root growth, or just trains the roots in a particular direction.…”

How can carbon be stored in the built environment? A review of potential options

“…In vernacular architecture, living plants have been used for loadbearing structures. For instance, in rural India, 'living bridges' have been grown from the aerial roots of ficus trees (Ludwig et al 2019). In addition, large-scale living 'arboscupltures' have been created for recreational parks (Gale 2011).…”

Photogrammetry as a Tool for Living Architecture

“…Living Root Bridges (in Khasi, Jingkieng Jri), grown by rural Khasi and Jaintia communities in Meghalaya (India), are the best known example of a functional living architecture (Ludwig et al, 2019). Rural village communities have used a single species, the Indian Rubber Fig, Ficus elastica, to grow more than 70 Living Root Bridges (LRBs), as well as ladders, pathways, and platforms.…”