The ingenious living bridges of India

As the tree ages, the aerial roots of the fig tree fuse together in a process known as anastomosis (Credit: Getty Images)

The ingenious living bridges of India

(Image credit: Getty Images)

www.bbc.com

Zinara Rathnayake

For centuries, indigenous groups in north-east India have crafted intricate bridges from living fig trees. Now this ancient skill is making its way to European cities.

When monsoon clouds bring pelting rains to the village of Tyrna, Shailinda Syiemlieh takes the nearest bridge to reach the opposite bank of a gushing stream. The bridge is no ordinary structure made of concrete and metal. Instead, it is composed of a single giant fig tree that sits by the riverbank, and the support that Syiemlieh walks over is a mishmash of aerial roots tightly knotted and woven together. The bridge is not only a part of the landscape, it is helping to support its ecosystem at the same time.

Tyrna lies just above the plains of Bangladesh in the north-eastern Indian state of Meghalaya, which hosts hundreds of these bridges. For centuries, they have helped the indigenous Khasi and Jaintia communities to cross swelling rivers in monsoons. “Our ancestors were so clever,” says Syiemlieh, “When they couldn’t cross rivers, they made Jingkieng Jri – the living root bridges.”

Meghalaya hosts some of the wettest locations on Earth. The village Mawsynram, the world’s rainiest place, receives an annual rainfall of 11,871mm (39ft) – that would be enough to submerge a typical three-storey house if deluged all at once. Nearby Sohra comes second, averaging 11,430mm (37.5ft). From June to September, monsoon winds sweep north from the Bay of Bengal, passing over the humid plains of Bangladesh. When these air currents meet the hilly terrain of Meghalaya, they break open – and torrential rains begin.

When monsoon downpours periodically isolated the remote villages of Syiemlieh’s ancestors from nearby towns, they trained living aerial roots of Indian rubber fig tree (Ficus elastica) to form a bridge across flooding rivers.

Researchers consider these living root bridges as an example of indigenous climate resilience. Aside from the connectivity they provide, these bridges attract tourists and help local people earn an income. Meanwhile, as researchers have found, they have regenerative effects on the surrounding environment. Scientists hope this concept of indigenous living architecture can help modern cities adapt better to climate change.

The trees are important not just for crossing rivers, but they hold a revered place in Khasi culture (Credit: Alamy)

The trees are important not just for crossing rivers, but they hold a revered place in Khasi culture (Credit: Alamy)

Building these bridges takes decades of work. It begins with planting a sapling of Ficus elastica – a tree that grows abundantly in the subtropical terrain of Meghalaya – in a good crossing place along the riverbank. First the trees develop large buttressing roots and then, after about a decade, the maturing trees sprout secondary aerial roots from further up. These aerial roots have a degree of elasticity, and tend to join and grow together to form stable structures.

In a method perfected over centuries, the Khasi bridge builders weave aerial roots onto a bamboo or another wooden scaffolding, wheedle them across the river and finally implant them on the opposite bank. Over time, the roots shorten, thicken and produce offshoots called daughter roots, which are also trained over the river. The builders intertwine these roots with one another or with branches and trunks of the same or another fig tree. They merge by a process called anastomosis – where branching systems like leaf vessels, tendrils and aerial roots naturally fuse together – and weave into a dense frame-like structure. Sometimes, the Khasi builders use stones to cover the gaps in root structures. This network of roots matures over time to bear loads; some bridges can hold up to 50 people at once.

The generations that follow the initial bridge builders continue the maintenance of the bridge. While only one single person may maintain small bridges, most require the collective effort of families or the entire village – sometimes several villages. This process of care and development down the generations can last for centuries, with some bridges dating from 600 years ago

As well as being a regenerative form of architecture, living root bridges grow stronger with time, self-repairing and becoming more robust as they age. “When it rains heavily, small cement bridges wash away and steel bridges tend to rust, but living root bridges withstand the rains,” says Syiemlieh.

“People came to realise that root bridges are much more durable than modern alternatives, and they cost absolutely nothing. So villagers now repair root bridges they had abandoned in the forest valleys.”

This resurgence in interest in root bridges is in part thanks to the efforts of Morningstar Khongthaw, a native from Rangthylliang village, who founded the Living Bridge Foundation. Khongthaw and his team create awareness about root bridges, repair and maintain old bridges while also constructing new ones.

The living root bridges of north-east India have become famous as a tourist attraction - but they could also inspire European urban architecture (Credit: Getty Images)

The living root bridges of north-east India have become famous as a tourist attraction – but they could also inspire European urban architecture (Credit: Getty Images)

Unlike conventional bridges, root bridges are also central to their surroundings. Apart from producing their own building material, the trees absorb the greenhouse gas carbon dioxide over their lifetimes. They help stabilise the soil and prevent landslides. Conventional bridges can disrupt the soil layers, but roots can anchor different soil structures which helps protect against soil erosion, says Ferdinand Ludwig, professor for green technologies in landscape architecture at the Technical University of Munich, who has been studying the bridges for 13 years.

This is true of many trees, but Ficus elastica plays a particularly important role in its ecosystem, says Salvador Lyngdoh, a local to Meghalaya and a scientist at the Biodiversity Institute of India, whose work focuses on conservation in the Himalayas. Fig trees are framework species that promote biodiversity around them: moss grows on them, squirrels live in their branches, birds nest within their canopy, and they support insects that help with pollination. The act of turning these trees into bridges can also help animals to thrive in their habitat, says Lyngdoh. Bark deer and clouded leopards are known to use root bridges to move from one part of the forest to another.

Root bridges may not be able to outperform the conventional kind in every sense, Lyngdoh notes. A conventional bridge can bear more weight, for example. “But root bridges are much more useful to a large sphere of natural species than the modern bridges we have,” he says. “The living root bridge is a mosaic that’s embedded within the forest. Species do not differentiate between the bridge and natural forest.”

This form of indigenous architecture has fascinated scientists like the Technical University of Munich’s Ludwig, for the potential to learn from them to make buildings and spaces in other parts of the world greener.

Ludwig sees these bridges as an example of not just sustainable development, which minimises the damage and degradation of natural systems, but of regenerative development. The latter attempts to reverse degradation and improve the health of the ecosystem. But understanding the living root bridges is not an easy process.

“There’s no one way to build these bridges,” says Ludwig. “How these roots are pulled, tied and woven together differ from builder to builder. None of the bridges looks similar.”

The lack of historical written information on the bridges has also been a challenge in researching them. Until the British colonial period in the 19th Century, native Khasi inhabitants in Meghalaya didn’t have a written script, as the Khasi way of life is passed down through oral histories. This has meant that documented information on the bridges is sparse.

The fig tree is uniquely adaptable to making root bridges, but other species can also be used to integrate into architecture, such as the London plane tree (Credit: Alamy)

The fig tree is uniquely adaptable to making root bridges, but other species can also be used to integrate into architecture, such as the London plane tree (Credit: Alamy)

So Ludwig’s team turned to conversations with Khasi bridge builders and digital tools to understand the bridge-building techniques. They started with mapping the complicated shapes of roots and built digital skeletons of the bridges; next, they used photogrammetry – recording, surveying and interpreting root bridges using photographs – to document the bridges and construct 3D models using them.

With this information, Ludwig’s team began designing a roof for a summer kitchen using a pavilion of trees, inspired by the root bridges.

“[Conventionally], when we construct a bridge or a building, we have a plan – we know what it’s going to look like,” says Ludwig. “But this isn’t possible with living architecture. Khasi people know this; they are extremely clever in how they constantly analyse and interact with tree growth, and accordingly adapt to the conditions.” Whenever a new root pops up, Khasi builders find a new way to integrate it into the structure.

But in Europe, with its very different climate, using Ficus elastica wasn’t a viable option, so they had to make compromises, choosing instead Platanus hispanica, the London plane tree. “That’s not all. The Khasi have incredible knowledge because they live in nature, and are deeply coupled with the ecosystems. We are not,” says Ludwig. So his team used digital tools to mimic this process and to settle on a geometry that allowed for weaving twigs together into a roof. The team constantly trims and prunes the trees to encourage them to grow to keep the trees thinner.

“We are learning how to react to plant growth in Europe: humans plant trees, trees grow, humans react, trees react again,” Ludwig says. “This way of interacting with nature is essential for a sustainable and regenerative future.”

The Double Decker Root Bridge of Meghalaya is now famous, drawing tourists from around the world (Credit: Alamy)

The Double Decker Root Bridge of Meghalaya is now famous, drawing tourists from around the world (Credit: Alamy)

Ludwig hopes that living architecture can contribute to improving the outer wellbeing of residents in cities. Integrating trees in buildings, bridges, and parks will help bring nature into crowded areas. “The idea is not to copy the bridges, but to borrow the elements of this indigenous engineering and try to understand how we can adapt it in our urban environments,” says Ludwig.

Julia Watson, architect and assistant professor at Columbia University, whose work revolves around nature-based technologies of indigenous knowledge, says part of this is changing the way we see trees.

“Instead of viewing trees in cities as passive elements, we can view them as active infrastructures, to expand the ecosystem services trees provide in the urban context,” she says. For instance, trees can reduce the effect of urban heat islands (where concrete structures absorb heat and keep cities warmer) and lower outdoor ambient temperature, Watson notes.

The Ficus elastica provides potential that goes far beyond bridges, Watson says. These trees needn’t be an add-on to a building, but an integral part of its façade or roof.

In Meghalaya, the Khasi’s practice of bioengineering takes integration of the trees with their surroundings one step further, bringing people together as well as the ecosystem. The bridges, Lyngdoh says, promote community life and create reverence within the society when people come together to build, maintain and repair the bridges.

The young bridges being trained today won’t be traversed by those who are tending to them now, but by generations to come. “The community doesn’t think of today. It’s a selfless act. It’s a conservation philosophy,” says Lyngdoh. He sees this selflessness as a sacred element that pulls the community together and protects the ecosystem. 

As well as being a part of Khasi culture, the root bridges have always brought economic benefits to the community. In the past, a network of bridges connected villages with nearby cities, providing a pathway for locals to transport and sell betel nut and broom grass. Today, there is also the tourism economy they bring, says Syiemlieh.

About 3,500 steps below Syiemlieh’s home village of Tyrna is the Double Decker Root Bridge that connects the two banks of the Umshiang River. When water levels rose high, Khasi villagers trained additional roots of the same fig tree across the river higher above the water, creating a second bridge over the first.

Today, it’s a major tourist attraction. As tourists began flocking, homestays opened. Locals built campsites and guided visitors through the hilly jungle. Makeshift stalls stacked up everything from crisp packets to bottled drinks. In March, when Syiemlieh visited Laitkynsew, a village just south of Tyrna, she saw locals pull, twist and weave aerial roots of a fig tree on bamboo scaffolding to build a triple bridge – two layers run parallel to each another as in the double-decker bridge, while a third root layer is slanted across the river bank. “Maybe they thought that three layers can attract more tourists,” says Syiemlieh.

Tourism comes with concerns, Syiemlieh says. Aside from the empty crisp packets and bottles, some root bridges see crowds of hundreds at a time as tourists clamber for selfies, potentially overburdening the trees. But locals are already planning different models of sustainable tourism.

Khongthaw, for example, is building a museum and a learning centre to educate tourists about living root bridges and other infrastructure made of Ficus elastica, such as canopies and tunnels in the deep jungles, and ladder-like structures, which farmers would use to climb up and down rock ledges on the way to Meghalaya’s fertile plains for cultivation.

Although still in its infancy outside Meghalaya, Watson hopes that architecture inspired by the living root bridges could come to play a fundamental role in cities – bringing with it benefits for urban air, soil and wildlife. “Living infrastructure can support incredible biodiversity and species, not just humans,” Watson says. “We need that biodiversity to survive.”

Join one million Future fans by liking us on Facebook, or follow us on Twitter orInstagram.

If you liked this story, sign up for the weekly bbc.com features newsletter, called “The Essential List”. A handpicked selection of stories from BBC FutureCultureWorklifeTravel and Reel delivered to your inbox every Friday.

Why climate lawsuits are surging

The number of climate-related lawsuits has more than doubled since 2015 (Credit: Getty Images)

Activists are increasingly suing governments and companies to take action against climate change – and winning. Could this be a turning point?(Image credit: Getty Images)

David Schiepek, a student from the southern German state of Bavaria, has been involved in climate activism for around three years. “After all this time fighting, protesting and talking to politicians, I was losing hope a bit,” the 20-year-old says. “I feel like my future is being taken away.”

But in May this year, an unexpected event gave him a fresh sense of optimism. A lawsuit brought by a number of environmental NGOs, on behalf of a group of young activists, resulted in Germany’s constitutional court ruling that the country’s climate protection act must be amended to include more ambitious CO2 emissions reductions. The decision stated that the government’s failure to protect the climate for future generations was unconstitutional.

“I saw that, finally, politicians can be put under pressure and forced to take measures against climate change,” Schiepek says. “It really changed the way I see politics.”

Now he is hoping to build on this ruling, which applies only to the federal government. He has been recruited by an NGO, along with other young people from around Germany, to bring similar cases against their local state governments. Technically, he is suing his state to take action on climate change.

The last few years have seen a snowballing of court rulings in favour of environmentalists around the world. The cumulative number of climate change-related cases has more than doubled since 2015, according to a report authored by Kaya Axelsson of Oxford University’s Environmental Change Institute and colleagues. Just over 800 cases were filed between 1986 and 2014, while over 1,000 cases have been brought in the last six years, researchers Joana Setzer and Catherine Higham of the Grantham Research Institute on Climate Change and the Environment found. Thirty-seven of those cases were “systemic mitigation” cases brought against governments.

One of the most high-profile was a Dutch case in 2015, in which a court ruled that The Netherlands’ government has a duty of care when it comes to protecting its citizens from climate change. The judges decided the government’s plan to cut emissions by 14-17% compared with 1990 levels by 2020 were unlawful given the threat of climate change. They ordered the target be increased to 25%. As a result, the Dutch government closed a power plant four years earlier than planned and introduced a new climate plan in 2019. Elsewhere cases have led to similar rulings – including the recent German one that inspired Schiepek, as well as cases in countries such as Australia.

The rising number of cases is paving the way for stricter enforcement of environmental laws around the world and giving activists like Schiepek a new sense of hope.

A number of high-profile rulings have found certain governments' and corporations' climate action has been insufficient (Credit: Getty Images)

A number of high-profile rulings have found certain governments’ and corporations’ climate action has been insufficient (Credit: Getty Images)

Roda Verheyen, one of the best-known environmental lawyers in Germany, and one of those who represented citizens in Germany’s constitutional court case this year, says she believes there are three reasons for the increase in successful cases. “One is that courts take a long time to actually come to conclusions,” she says. An increasing number of cases have been filed since 2014, so some are only now being heard after many years of work.

On top of this, the scientific evidence that climate change is caused by humans has become undeniable, meaning it is much easier for lawyers to prove this in court. And the governing laws that countries are expected to follow have also developed and expanded – Verheyen points out that back when she first started studying law around three decades ago, there was nothing remotely related to climate.

“And then obviously the narrative of what society perceives climate change to be has changed,” she explains. “A lot of law is flexible to some degree, because you always have to interpret existing rules. And when [judges] do that, they take into account societal norms and how belief systems might have changed.”

She compares this development to marijuana-related offences – as attitudes towards the drug have become more liberal in many countries, sentences have become much lighter. In the context of climate change, the public now overwhelmingly accepts the scientific consensus that it is man-made, and polls regularly put it towards the top of peoples’ concerns. This has in turn made courts more willing to rule against those responsible for emissions.

Verheyen explains that this year’s German ruling is significant because many countries do not have a constitutional court that can make this type of decision. Secondly, it is unlimited, so applies from now until forever, and she expects it to have a big impact on other cases around Europe.

Roda Verheyen successfully represented citizen's in Germany's constitutional case in 2021 (Credit: Alamy)

Roda Verheyen successfully represented citizen’s in Germany’s constitutional case in 2021 (Credit: Alamy)

As well as cases against governments, cases against corporations have also been gathering pace. One landmark ruling of 2021 was again in The Netherlands, where oil giant Royal Dutch Shell was ordered to cut its emissions by 45% by 2030, compared with 1990 levels. Shell has said it will appeal the ruling, while stepping up efforts to reach net zero emissions by 2050.

A Royal Dutch Shell spokesperson says the company is “rising to meet the challenge of the Dutch court’s ruling” and has committed to reducing its Scope 1 and 2 emissions by 50% by 2030, compared with 2016 levels – these are Shell’s direct emissions from owned or controlled sources, and its indirect emissions from the generation of purchased electricity, steam, heating and cooling.

“Our 2022 business plan will reflect this new target, which we are committed to delivering regardless of whether we win or lose our appeal against the ruling,” the Shell spokesperson says.

These reductions don’t include the emissions from burning Shell’s fossil fuel products, which come under the category of Scope 3 emissions. The Dutch ruling stated that the company also needed to reduce its Scope 3 emissions, but the Shell spokesperson says that these findings hold Shell accountable for a wider global issue.

Paul Benson, a lawyer at Brussels-based NGO Client Earth, which specialises in environmental litigation, says this case “sought to apply the same reasoning [from the ruling against the Dutch government] to a corporate body. That was very novel, and I think a lot of commentators and people in our fairly enclosed legal circle weren’t entirely sure what way the court would interpret [that].”

“I was thrilled for a court to find that a company’s climate policy is in effect inadequate,” he continues, calling the judgment “ground-breaking”. The case was also the first time that a company was ordered to comply with the Paris climate agreement: “[It] shows the Paris agreement has teeth – not just against governments, but against companies.”

This has paved the way for other lawsuits seeking to force corporations to comply with the treaty – Verheyen is currently working on a lawsuit against German carmakers BMW, Mercedes-Benz and Volkswagen which, if successful, would force them to phase out combustion engines by 2030 in line with the Paris goals. “As you would expect, actors in this space and lawyers in our community have been studying the [Shell] judgement very carefully, and sought local reasoning to apply [it] in their jurisdiction,” adds Benson.

“The complaint has not yet been served on us,” says a spokesperson for Daimler, which makes Mercedes-Benz vehicles. “We do not see a basis for a cease-and-desist declaration, because we have long since issued a clear declaration for our ‘lane change’ to climate neutrality: As a car manufacturer, it is our ambition to become fully electric by the end of the decade wherever market conditions allow.”

A BMW spokesperson says: “The BMW Group is firmly committed to the Paris climate agreement and already leads the automotive industry in the fight against climate change.” Meanwhile a Volkswagen spokesperson says that Volkswagen was the first car manufacturer to commit to all targets set by the Paris climate agreement “and is committed to become net carbon neutral at the latest by 2050”, aiming to invest €35bn [£30bn/$40bn] in electric mobility before 2025.

Benson and one of his colleagues, Sebastian Bechtel, both stress that the cases taking place now only challenge a fraction of environmental destruction that is happening around the world. Many activists do not have the financial resources to take on big corporations. “A lot of countries do not want to bring these claims,” Bechtel says. “In the UK, those relate primarily to costs. In other countries, it’s simply not possible to go to court to enforce specific laws.”

Increasingly solid science proving anthropogenic climate change and shifting public sentiment are two reasons for the uptick in climate lawsuits (Credit: Getty Images)

Increasingly solid science proving anthropogenic climate change and shifting public sentiment are two reasons for the uptick in climate lawsuits (Credit: Getty Images)

Back in Germany, a newly launched NGO, Green Legal Impact, is seeking to address this issue by offering specialised training to young lawyers and connecting civil society groups to those offering legal representation. Managing director Henrike Lindemann says that as a young environmental activist she “always saw that young people had political ideas. And then there were lawyers, often old white men, who told us our ideas were not possible because of the law,” she says. “And I thought, I want to know for myself if this is true. And if it is, I want to know how to change it.”

Lindemann says that one of the aims of the organisation is to encourage activist groups to be strategic in the court cases they pursue, so that any judgments can pave the way for further litigation. She gives the example of a number of current cases challenging the planned 850km (530 miles) of motorway due to be built in Germany, which she argues has not been looked at through the lens of climate. “I think if the court [ruled against one part of motorway], the discussion would change,” she says. “It would not just be about that one section of motorway, it would be the entire plan. And then we would have to change the whole discussion around mobility.”

The question of access to justice also brings about the issue of whether those in the Global South, who are disproportionately impacted by climate change, could in future bring cases against corporations or governments in wealthier nations. Green Legal Impact is already working on helping people in other countries who have been impacted by German companies’ actions seek justice, and a recent UK ruling stated that communities can sue parent companies for environmental damage caused by their subsidiaries.

Verheyen says it would be difficult to find courts to support cases against foreign governments, “unless at some point one very severely hit country decides to go state-versus-state, which has been a topic of conversation in academic and political circles for a long time, but hasn’t happened.”

Environmentalists are feeling optimistic after this year’s judgments. But given how slowly courts move, do they feel this may all be too little, too late? “Obviously I don’t think it’s too late, otherwise I would stop what I’m doing,” replies Verheyen. “I think we’re actually seeing a lot of movement.”

Benson agrees. “I think there’s a tendency sometimes for people to think about climate in a fatalist way,” he adds. “But everything we do now to mitigate and adapt is hugely worthwhile.”

In terms of which potentially ground-breaking cases we might see in future, Verheyen suggests that both the finance sector “and anything to do with land use and forests” are areas where she is expecting more action to arise. “If you look closely at the Shell judgement, it says, no further fossil fuel investment, full stop,” she explains. “If I was a financial institution, I would be looking very closely at that one.”

But overall, lawyers working in this field are keen to point out that litigation isn’t a silver bullet for ending the climate crisis. “It’s just one of the levers that can be pulled to trigger necessary change,” says Benson. “The other levers are activism, policy and, of course, science. But [litigation] is an incredibly powerful tool, and I think this year we’ve seen that.”

Join one million Future fans by liking us on Facebook, or follow us on Twitter orInstagram.

https://www.bbc.com/future/article/20211117-how-indias-living-bridges-could-transform-architecture?utm_source=pocket-newtab-android

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.