These are the living bridges made from tree roots in Cherrapunji, India.
Five hundred or so years ago, locals discovered a way to shape the roots of the Ficus Elastica tree (commonly known as the rubber tree) in a way that could provide the strength and support necessary for bridging rivers.
The rubber tree’s roots branch off the trunk higher up and cascade down in large fan shapes to the ground where they take root. To make the bridge, locals used hollowed out betel nut tree trunks as guides to direct the roots over the river and keep them from fanning out. When the roots grow to reach the other side they’re directed down to the soil where they take root and anchor themselves. Over time, the roots grow thicker, stronger, and deeper, making ideal supports for a sturdy platform.
Root bridges can take ten to fifteen years of growth before they reach the capacity to carry people’s weight. But, once they are established and matured, these root bridges continue to become stronger and stronger to the point where some can support the weight of fifty people or more. And, as the trees become relied upon for supporting these important transportation routes, the locals tend to them and have a vested interest in making sure they remain healthy. Another good example of the powerful symbiotic relationships people can have with other living things.
For more info about rootbridges see rootbridges.blogspot.com