Text by: Nishanth Srinivas
Meghalaya is the wettest region on Earth. It is geographically a single massif of tableland riddled with outflowing streams creating narrow, steep-sided slopes. Living root bridges (LRBs) are the crucial passageways for rural communities located on these slopes, as they allow them to cross the shallow canyons and gushing rivers. The concept and architecture of these bridges is fascinating to anyone visiting Meghalaya. I was eager to see these living bridges myself, so I travelled to the most popular one at Mawlynnong village. There were many vehicles and a constant flux of people climbing up and down the steps leading to the bridge when we got there. After descending a little, we neared a fast-flowing stream. To the left was a unique example of structural engineering—an archaic, environment-friendly and possibly carbon-negative bridge that was alive and growing.
The bridge appeared to be a fused structure of the roots of three ficus trees, with two trunks on one side of the bank and one on the opposite bank. The bent trunks were covered with a green patina of moss and topped with a high arching canopy. The sides of the bridge were roots meshed like an intricate filigree. The bridge’s floor, which was a few metres long, was laden with flat rocks and mud, providing firm cushioning for walking.
(Left) Closely intertwining roots grow together and, in time, form a densely interwoven framework. The simplest connection is formed when two roots cross each other and self-graft. (Right) The addition of handrails, underpinning struts, suspension constructs etc., can further strengthen the bridge’s structural system. Photos: Ashwin Ezhumalai
Cover photo: A living root bridge is locally called jingkieng jri in Meghalaya. This famous double-decker root bridge at Nongriat in the East Khasi Hills district is estimated to be around 200 years old. Cover photo: Ashwin Ezhumalai
Ficus in the abode of clouds
LRBs are created by training the aerial roots of the rubber fig tree (Ficus elastica), native to the region. Rubber fig is a type of strangler fig with aerial prop roots that help it to establish dominance over the host plant it germinates on. During the initial stages of its life, it lives like an epiphyte (growing on the host plant). In time, as the roots grow and reach the ground, they mature and smother the host tree with their roots and huge spreading canopy. At this point, the aerial roots also provide structural support to the massive canopy. Trees like ficuses have the property of “inosculation”. Inosculation is a natural process where branches or roots in close proximity grow together as one. The branches or roots in contact with each other self-graft and grow into a single structure over time. The native Khasi and Jaintia communities in Meghalaya utilise these unique properties of the tree to solve the equally unique problem of connectivity within the slopes.
(Left) Aerial roots by evolutionary design were intended for mechanical support of the massive ficus trees. As this tree matures and develops, the structurally altered aerial roots are able to serve as a bridge.(Right) A young, growing yet functional living root bridge. Photos: Ashwin Ezhumalai
Growing a bridge
To build a bridge, a single tree is planted on one side of a river, or two trees are planted, one on either side of the river bank. Once the main stem establishes itself, the young, pliable aerial roots are trained horizontally. Community members intertwine the roots and place them in hollowed out areca trunks, which provide the micro-conditions necessary for root growth. This structure in turn is supported by bamboo scaffolding which spans the length of the river and also acts as a temporary bridge for the community. Once the roots reach the opposite bank, they thicken and produce secondary roots which are woven back into the structure. At any point in time, the bridge is interlaced with roots of varying ages. The bamboo scaffolding is periodically renewed or replaced to accommodate increasing root girth and damage from the prevalent humid conditions. As the roots become more integrated and inosculated with the primary root system, newer roots are trained as handrails to make the structure secure. Weight is added in the form of stones, planks and soil to fill the gaps in the root meshwork. The added weight also tests and strengthens the structure. The roots act like beams and suspender cables carrying the entire structure. Over a period of a couple of decades, the root assemblage is strong enough to support significant pedestrian movement, with mature structures able to carry more than 20 people at a time. This kind of structure can last for centuries. Along with providing access to villagers on either side of the stream, the bridges, in recent times, have become important tourist attractions and a potential source of income for the local population. However, with more than 100,000 tourists visiting some of these bridges annually, the heavy footfall can adversely affect the life of the root bridge.
(Left) Once ficuses start developing aerial roots, they are guided horizontally over bamboo scaffolding to reach the opposite bank. The scaffold acts as support and a temporary bridge. (Right) After years, the constantly worked upon and growing roots come under tension, thicken, and self-graft, forming connections. Weights in the form of small stones and wooden planks are laid to cover holes in the structure, as seen in this bridge at Nongriat. Photos: Ashiq Binyameen (left), VisualCommunications/Getty Images (right)
Bridges built out of bamboo, concrete or steel cables though present, are not ideal in the region. With heavy precipitation (over 700 cm of rainfall in just two monsoon months), the bridges can be washed away and are prone to age-related damage. In contrast, mature LRBs can tolerate rain and floods, and their structural resilience only increases with time.
Since they’re made of a native keystone species like Ficus elastica, the bridges provide resources for the regional fauna and are part of the local ecology. The time it takes to train such a bridge, and the fact that they are not sturdy enough to be motorable pathways are the main limitations of LRBs.
(Top) Living root bridges act as scaffolds of biodiversity. Mature Ficus elastica trees sustain native fruit-eating birds and mammals while also supporting communities of mosses, lichens, and epiphytes growing on them. (Above) Residents involved in the intertwining and maintenance of roots of a living root bridge near the village of Kongthong. Photos: VisualCommunications/Getty Images (top), Anselmrogers, CC BY-SA 4.0 (above)
Bridging development and nature
The beauty of the LRB system is not just in its sustainability, low maintenance costs, and high durability. It represents a collective human-plant interaction aimed at providing a service to future generations. Multiple generations of “bio-engineers” contribute over decades to shaping a single bridge and maintaining it thereafter. LRBs are a product of resourcefulness and self-governance—the bridge is grown by and for the community, using locally available resources.
The aspect of LRBs being alive is not their only distinction. This living local heritage is a unique global example of how solutions for human problems can be long-term, posterity-centric, and all-inclusive while still being seamless and integrative with nature. Modern architecture has shown this to be possible even in big cities. The Bosco Verticale building in Milan, Italy and the Supertrees of Singapore’s Gardens by the Bay are other examples of such integration.
Despite being minuscule in scale, the concept of LRBs flies in the face of large developmental projects we regularly hear of, which have a negative impact on the environment. LRBs represent a unique synergy of human ingenuity with nature. We ought to emulate that synergy in our infrastructure development and design for the entwined future of our planet and ourselves—which is as intertwined as the bridges’ roots.
