Interwoven in the living root bridges are stories of biodiversity and human interactions

For hundreds of years, aerial roots of the rubber fig tree (Ficus elastica), patiently coaxed by human hands guided by traditional knowledge, have created sturdy lattice-works, forming living bridges across Meghalaya’s gushing streams and canyons. Over 70 living root bridges (LRBs) thrive in the state’s mountainous rainforests in one of the world’s wettest regions – evidence of an enduring relationship between a pollinator, seed dispersers and indigenous communities.

In a recent study, scientists document the identification of a pollinating fig wasp (Platyscapa clavigera) from rubber fig trees in Meghalaya, northeast India. This is the first record of the species in the region, which is the westernmost portion of the fig’s range restricted to South and Southeast Asia. The pollinating fig wasp species was first described from F. elastica in Bogor in 1885 and from Singapore in 2017. The scientists also report a non-pollinating fig wasp from the syconia (fleshy, fruiting bodies) of the fig species in Meghalaya. The study is evidence that the pollination system of the fig species and its unique pollinator Platyscapa clavigera is still intact in Meghalaya, whose government has sought UNESCO recognition for the LRBs as a World Heritage Site as the hill state marked its 50th year of statehood in 2022. The living root bridges face a lack of repair and maintenance and unchecked tourism pressures among many other threats to their sustainability.

Within the broader priorities of biodiversity conservation, preserving the riverine vegetation and the ecosystems that flourish in link with the bridges (called Jingkieng Jri locally) helps conserve the environment in which pollinators and seed dispersal agents can thrive, explains the study’s corresponding author Renee Borges, professor at the Centre for Ecological Sciences, Indian Institute of Science, Bengaluru. “… especially since we know nothing of how climate change will affect the movement of pollinators that are largely blown by winds before they actively navigate to their targets. Pollinators could suffer from thermal stress about which we know very little today,” she says.

“Without the pollinator, you will not have the Ficus tree; without the Ficus tree you will not have the pollinator,” botanist Lucy Nongbri who trekked across the state to unravel the mystery behind the pollinators, told Mongabay-India, emphasising the Ficus trees’ keystone role in nature: they hold the ecosystem together and promote biodiversity around them. They are hospitable to birds and bats (seed-dispersing animals) that feed on their fruits; they stabilise the soil with their root system and prevent landslides, among many other functions. In recent years, biologists also discovered a new species of swamp eel near a stream in the Khasi hills, close to a living root bridge.

The identification of Ficus pollinators and seed dispersers is one of the many site-specific conservation objectives and landscape/ecosystem-based habitat conservation being discussed by the Meghalaya government as it works towards finalising the draft Guidelines for Protection of Living Root Bridge Ecosystems that it drew up in 2018 consulting scientists (including Borges and Nongbri), conservation experts and policymakers. The draft guidelines, the government says, are underpinned by science-based approaches and community participation.

Fig tree populations are mainly distributed in East Khasi Hills and West Jaintia Hills. The study, which involved trekking to remote terrains in 2017, was restricted to a few trees in the East Khasi Hill district. In its natural habitat, F. elastica is a strangling fig. It germinates and grows on the branches of an existing non-Ficus tree and this sapling grows upwards and downwards and sends out aerial roots and later terrestrial roots when it reaches the ground.

“In this process, the F. elastica plant strangles the existing tree,” points out Borges.

The scientists found that many trees did not flower/fruit during the study which may mean that they have been derived from vegetative cuttings and for some reason are sterile. Next, they intend to investigate the genetics of the F. elastica trees of the living root bridges and of trees in other parts of Meghalaya, including saplings so that “we can determine the gene pool of both the trees and of the pollinators. We hope to begin this study very soon,” added Borges.

The scientists also conducted a two-day workshop on Ficus elastica biology at Nowhet village in 2017, where attending local communities showed a keen interest to learn and to cooperate in discovering new facts about the bridge trees and their biology. The workshop was supported by the government and the National Geographic Society Expedition Grant.

“While the local communities did not have an understanding of the pollinators and dispersers but they said they collect the F. elastica seedlings from top of other plants and they start planting in suitable locations to form the bridge,” said Nongbri who attributed the presence of the saplings on other trees to the movement of birds and bats who deposit them on the other trees. Many locals have lost their indigenous knowledge, observed Borges.

MorningStar Khongthaw, founder of the Living Bridge Foundation (LBF) working to preserve living root bridges and encourage ecotourism with the participation of living root bridge communities, says the organisation is also trying to raise awareness levels among tourists and students about the root bridges.

“There is an uptick in concrete infrastructure including concrete walkways and bridges while older root bridges are often found in a state of disrepair; children’s habits have changed in the formal education system… they go from school to tuitions and back home, without knowing how valuable these structures are,” Khongthaw who hails from Rangthylliang in Pynursla, Meghalaya, told Mongabay-India.

The draft guidelines to protect the living root bridges include zone-based conservation and a responsible development approach for regulating activities, including tourism, in conformity with peripheral distance from Jingkieng Jri (core LRB structure), according to details shared by the Meghalaya government’s Meghalaya Basin Management Agency, with Mongabay-India via email.

For example, the proposed Zone I suggests declaring at least approximately 30 meters from the core LRB structure as a protected area to ensure ecosystem services provided by LRBs remain intact.

The guidelines also emphasise forming Village Cooperative Societies for inclusion of all stakeholders, ensuring an equitable profit-sharing model, and nurturing sustainable livelihoods; precise evaluation of each jingkieng jri with a specific focus on ecosystem health and growth; establishing ‘ecosystem carrying capacity’ and ‘load-bearing capacity’ of LRBs to inform future development. Currently, living root bridge co-operatives are involved in ongoing LRB site-specific restoration up to at least 25 meters, nature-based livelihoods, and declaration of a 25-meter core zone as Law Adong (protected forest), among others.

The ongoing Community-Led Landscape Management Project (CLLMP) of the state government is field-testing the draft guidelines with the primary stakeholders (communities). The final guidelines will incorporate the lessons from this process, the government said.

Borges adds that regulating development actions, such as tourism, will have to be “careful and balanced” so as to factor in the livelihood need of the community and ease pressures on the living root bridges.

She is in the process of designing data collection sheets for a participatory data collection effort involving the villages that have signed up for the cooperatives to generate baseline data on the organisms and features associated with the living root bridges. “The communities understand co-operation and their activities are underpinned by strong principles of local governance which come into play in the co-operative structure. Local groups are also working with villages that haven’t signed up for the co-operatives to understand their reluctance and their issues which are crucial to scale up conservation efforts,” she said.

MorningStar Khongthaw says the benefits of the conservation and management actions must trickle down to the local communities who remain at the core of the bridge building, maintenance and repair, for long-term benefits to biodiversity and climate action. Biodiversity loss and ecosystem degradation undermine the supply of ecosystem services vital for mitigation and adaptation, states the UNEP-WCMC.

The Zoological Survey of India also plans to engage local communities in monitoring the biodiversity in the LRB ecosystem. Based on a recent visit to living root bridges in the East Khasi Hills, the organisation aims to undertake studies on the identification and evaluation of all fauna (from microbes to mammals) within the LRB ecosystems “which will be helpful to develop health cards of each LRB since a lot of micro-fauna like nematodes and other parasitic species directly affect the health of Ficus elastica trees,” explained Jasmine, a ZSI scientist. Research on the living root bridge ecosystem will help support the upgradation of LRBs to UNESCO World Heritage Sites, contributing to conservation and responsible development of all stakeholder villages added ZSI Director Dhriti Banerjee.

Banner image: The fig wasp pollinator inside the syconium in the dispersal phase. The greyish color bodies are the pollens from the male flowers that are adhered to the pollinator’s body at this stage. The pollinator exits the syconium at this stage and flies to other trees which are in the pollination phase, to pollinate another tree. Photo by Nikhil More.