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It was a cloudy monsoon afternoon, and I had been trailing my guide Bah Drong for over an hour. Despite the slight but persistent drizzle, Bah Drong marched along unfazed, his seasoned calf muscles carrying him swiftly along the rough, mountainous trail. I had to hurry to avoid falling behind. Every now and then he turned to offer encouragement with a few words of broken English and a mouth full of betel nut seeds: "Little more!"

It would take us another full hour to find what I had come to see: A being that was both intrinsically natural and intrinsically engineered, a "

," or a living bridge made out of tree roots.

The word comes from the local (phonetic) language called Khasi.

I was in the northeast Indian state of Meghalaya, which translates to "abode of the clouds." Here, at the foot of the Himalayas, lie the Garo and Khasi ranges, which endow the landscape with undulating hills, deep valleys and fast-flowing rivers. Every monsoon season, rain-laden winds sweep up from the Bay of Bengal, breaking open upon this mountainous terrain and creating what's widely considered to be the wettest region in the world. On average, this area receives between 32 and 45 feet of rainfall a year.

These hills are home to the Khasi people, a mountain tribe who, for centuries, have made this harsh landscape their own. Their primary occupation is farming, often supplemented by fishing, growing betel palm, fermenting rice beer and distilling spirits from rice or millet. Some villages have concrete houses, but most locals prefer traditional bamboo dwellings, slightly elevated from the ground so water can flow under them.

During the dry season, the community's focus is split between farming and preparation for the rainy season.

When the rains begin, usually in June, they continue for four to five months, and life slows down to a standstill. This is a time for staying indoors and socializing. With the advent of electricity, board games have been replaced by mobile phones and television, but drinking beer and telling stories haven't lost their charm.

Far removed from the populous cities, the villages that dot these hills are remote and sparsely inhabited. Over the centuries, the Khasis have learned to adapt to the specific challenges this landscape creates. They have learned to delicately mold the landscape into a form they can inhabit.

There is perhaps nothing else that exemplifies this more than the 

When I think back to my own arduous trek across this hillscape, I begin to comprehend how much the geography of this place is characterized by isolation and disconnectedness. Even today, most of these villages do not have road access. A trip to the closest town might require climbing down into valleys and crossing flooding rivers to reach another village. 

But crossing these rivers isn't possible without a bridge. 

It's hardly surprising, then, that it was the need for connectedness that provided the first guiding impulse for these ancient experiments in bioengineering. Tree bridges are structures that are literally rooted in the terrain and that thrive under the relentless pressures of the wettest land in the world.

The raw materials for building these bridges are rubber fig trees (

). That's because they are very elastic, and they put out aerial roots. First, an ideal location on the river is identified for the bridge, and then people go into the forest and find healthy 

 saplings to replant on either side of the river.

After a wait of 10 to 15 years, the trees are old enough to put out aerial roots,

 which the bridge builders then coax across the river with the help of bamboo scaffolding. This scaffolding doubles as a temporary way for pedestrians to cross the river while the bridge is under construction. Over the years, the aerial roots are pulled and woven to meet the tree on the other side of the river. The roots are tied with each other and over the years they begin to merge by a process of fusion known as anastomosis.

Once the tree has reached a certain level of maturity, it adds more roots to the network, which the local people weave into the bridge. After the entire network of roots has sufficiently matured, the bridge reaches a critical strength capable of supporting pedestrians.

This is the standard method used in root bridge-building. But after exploring and photographing over 25 such structures and speaking with those who use them most, I came to realize there is no one way to construct or grow these bridges, and no two bridges look exactly alike. I found bridges in their very early stages of development and some that were centuries old. 

In the early stages of growth there is more maintenance as villagers guide and tie new roots into the existing bridge. Sometimes they'll build bamboo handrails to prevent people from falling off. In addition, the villagers will stuff fallen leaves inside the gaps of the root network so they may decompose into humus and provide nutrition for the bridge.

The more I learned, the more I realized how conventional vocabulary related to building and construction simply did not seem adequate to describe this process. As I walked across my first 

, my mind darted this way and that, trying to find a comparable experience. No, it did not feel like crossing a concrete bridge. No, it did not feel like climbing a tree. Instead, it felt like a fairy tale come to life. And perhaps, in a way, that's what it is.

In a place where concrete bridges are unlikely to survive even a few decades due to earthquakes, landslides and floods, these bridges grow stronger, more robust and resilient with age. They do not require revenue to build, only time.

What's more, the root bridges don't just support humans who cross over them. Studies suggest that a single 

up to a few hundred living species — birds, insects, sometimes mammals and vegetation like moss. The trees themselves are ecosystems, constantly interacting with their living and nonliving surroundings.

Exploring and photographing these bridges wasn't easy. The mountains were never-ending, and the villages remote. Except for a few areas frequented by tourists, gaining access to faraway villages took time and planning. Even once I reached a village, getting to a root bridge was always a difficult task. As most bridges lie in valleys, reaching them usually required treacherous treks up and down hills for hours on end, often along damaged and slippery trails, with torrential rainfall for company. All this while carrying heavy camera gear that had to be kept dry. It was a lesson in endurance.

While documenting different aspects of these bridges, I was keen to photograph them in a unique light. The idea was to isolate these monumental bridges from the rainforest background that engulfs them. I was certain of only one thing: illuminating my subject with multiple fixed light sources was not an option, as it would require ferrying much equipment to such a remote location and might also disturb the bridge ecosystem with constant bright light.

After extensive research and advice from a photographer friend Anand Varma, I settled on a age-old technique known as light painting.

Essentially, with an exposure time of approximately few minutes, I would hold the portable light source as I walked the length and breadth of the bridge, aiming light at some areas and letting others go dark for the photograph. In addition, I put fixed lighting in specific places, sometimes behind the bridge, to add layers of highlights, bringing certain branches and elements of the bridge into focus.

After many nights, I began to get a sense of what to illuminate and what to leave in shadow, which bridges would benefit from the ambient light of the moon and which would retain their mystery without it. When I showed my results to my friends from the villages, they often couldn't believe they were looking at their very own bridges.

As fantastical as they appear, these bridges face very real issues today. Some have become tourist spots, and hundreds of people visit them during the rainy season when the forests are lush and inviting. 

Tourism, here as everywhere else, is a double-edged sword. It has undoubtedly brought in steady income for these villages: Locals make money from home stays and guiding, and even the state government has begun to fund tourism development. But these bridges are built to withstand the weight of occasional local pedestrians, not of hundreds of tourists scrambling for selfies. Some bridges have begun to show signs of physical damage. 

Besides this, government funds have been used to build concrete stairs, walls and ticket collection stands, often right next to these bridges, posing a long-term threat to their stability and sometimes blocking the roots.

Fortunately, many locals are increasingly aware of these threats and are working toward developing a more sustainable model of tourism — for example, by considering a limit on the number of tourists.

As Bah Drong and I hiked back from our trip to the bridge, my mind was buzzing with thoughts of how much knowledge these bridges hold — for engineers, architects, ecologists, anthropologists and others. They are living, breathing examples of life in the past that can help us create sustainable lifestyles for the future. 

When I shared my thoughts with Bah Drong, he agreed. These bridges are special, he told me: That's why his people build them.

He told me that they fully intend to keep maintaining the useful bridges, making sure they last as long as possible. 

I asked him what happens to the bridges that are no longer in use. He smiled at me and said, "They'll become a part of the forest, my friend."

A molecular biologist turned photographer, 

 focuses on natural history and science stories in Asia. He now combines his experience in research with his photography skills to popularize ecological and conservation sciences in the wider society. He is currently working on a story for 

Arts and Culture

Prasenjeet Yadav

Author

In the Indian state of Meghalaya, one of the wettest places on Earth, villagers are separated by rivers and valleys. To stay connected, they coax tree roots to grow together into living bridges.

Photos: Living tree bridges in a land of clouds

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