The nearly magical properties of fig trees

In Cherrapunji, India, locals mold the roots of the fig species Ficus elastica tree into living bridges. Credit: 2il.org Flickr (CC BY 2.0)

Living bridges made of fig tree roots in Cherrapunji, India

When the Indonesian island volcano Krakatoa erupted in 1883, the waves it sent forth crashed into Bantam, some 50 kilometers away in western Java, and flattened forest for a distance of more than 300 meters inland. All that remained standing, said French scientists who visited a year later, were tall fig trees, their bare branches reaching skyward.

Back on Krakatoa there was no trace of life. Much of the island had vaporized, and what was left was buried under a 60-meter deep blanket of ash. Yet before long, several species of fig trees grew there too. They had arrived as seeds defecated by wandering birds and bats. They soon produced figs that drew in more flying animals, which in time carried the seeds of dozens of other tree species. And so, from black lava, a forest grew anew.

The physical strength, resilience and animal magnetism of fig trees are powers we can tap as we grapple with the Earth’s fast-changing climate. As my book Ladders to Heaven (US title: Gods, Wasps and Stranglers) shows, humanity has long benefited from these trees as sources of materials and medicines, food, shade and security. As the world warms, we may need them more than ever.

That’s certainly true in the Indian state of Meghalaya, the most rain-soaked inhabited place on Earth. The Khasi and Jaintia people who live in the forested hills there train the aerial roots of Ficus elastica fig trees into living nets that prevent landslides and living bridges that save lives when monsoon rains turn streams into raging torrents.

Some of these bridges are thought to be centuries old. By contrast, steel suspension bridges last just a few decades. Bangalore-based architect Sanjeev Shankar says fusing fig roots with steel bridges could create stronger, longer-lasting hybrid structures. He also thinks people in other countries could use the living roots of their own local Ficus species to create structures that build resilience to extreme weather.

But fig trees aren’t only valuable in wet places like Meghalaya. They are also helping people adapt to the growing threat of drought. Farmers in Ethiopia, for instance, are embracing a fig species called Ficus thonningii. These trees need no irrigation, yet their leaves provide vital moist fodder for livestock. They enrich the soil with leaves that fall and decay, and they improve the growth of crops planted in their shade instead of the blazing sun.

Research by Mulubrhan Balehegn and colleagues at Mekelle University shows that planting this species instead of the usual fodder crops can boost production by 500 percent, while reducing inputs of water by 95 percent. Goats that eat the fig tree’s leaves produce more and better quality meat than those given only commercial feed.

Over the past decade, Balehegn and his colleagues have encouraged 20,000 households to plant this tree. They hope farmers will follow suit in the 33 other African countries where Ficus thonningii grows, and urge people to take similar approaches with fig trees in arid areas of India and China.

Crucially, planting fig trees doesn’t just improve livelihoods and help people adapt to the changing climate. By storing carbon, the trees can also play a part in slowing the rate of warming. All trees store carbon as they grow, but—as on Krakatoa—fig trees also encourage the growth of other tree species because their figs attract a diverse range of seed dispersers. In Costa Rica, Thailand and South Africa, researchers are harnessing this power by planting fig trees to accelerate reforestation on logged and mine-scarred land.

Elsewhere, people have traditionally used the presence of Ficus species to divine water, helping them decide where to plant crops or dig wells. Others have planted, or left standing, large fig trees as natural umbrellas against the heat, or have stored dried figs to turn to in times of drought and famine.

In fact, fig trees were among the first plants people domesticated. They have been helping people survive in hot and arid lands for thousands of years. As the world warms, the edible fig (Ficus carica), now grown in at least 70 countries, will grow in importance.

Rising temperatures also pose challenges to fig trees and the tiny wasps they depend on to pollinate their flowers. But this relationship between the plants and their pollinators has endured for 80 million years longer than humans have walked the Earth. The fig trees survived the extinction event that saw off the giant dinosaurs, and lived through periods warmer than what we experience today.

By contrast we are new here. Our future is made insecure by the slow pace at which we are removing carbon from the atmosphere, and our limited capacity to adapt to the resulting climatic change. The good news is that fig trees can help us to do both.

This post was first published (here) by Scientific American.

Photo credit: 2il.org Flickr (CC BY 2.0)

Read more about fig trees in my book Ladders to Heaven (published in North America as Gods, Wasps and Stranglers). For a summary and reviews from Annie Proulx, Deborah Blum, Michael Pollan, Sy Montgomery, Simran Sethi, David George Haskell and others, visit this page.

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Religion + fig trees = a boost for biodiversity

Hanuman-temple-and-fig-tree-Ficus-religiosa-in-Bangalore-Anoop-Negi

A sacred fig tree at a Hindu temple in Bengaluru (Bangalore) – credit Anoop Negi

When Tarsh Thekaekara and Shruti Agarwal spotted a lone fig tree in sea of tea bushes in southern India, they knew it had to be special. The researchers were documenting sacred groves in tea plantations to see if they helped conserve wild species. They learned that the fig tree was all that remained of a grove consecrated by local Paniya people who, for generations, had convinced tea estate managers not to fell the tree.

As in many other countries, fig trees have been sacred species in India for thousands of years. Wherever they grow, figs are also key resources for wildlife. Thanks to their curious biology, they feed more bird and mammal species globally than any other fruit and so sustain the seed dispersers of thousands of other plant species. In India, and in many other countries, fig trees could play key roles in protecting biodiversity and regenerating lost forests — but policies to protect these trees are rare.

Writing in the Indian Express, Thekaekara and Agarwal tell how they returned to the lone fig tree and set up camera traps to find out what wildlife visited. They soon recorded monkeys, many bird species, civets and a species of flying squirrel. “As the figs ripened and fell to the ground, the place really came alive,” they write. “Porcupine, wild boar, barking deer, sambhar deer, bear and, even, an elephant! A leopard also walked by, probably feeling like she was missing the party, and to try to dine on a couple of fig-eaters!”

Thekaekara and Agarwal highlight the important ecological role the tree plays in a landscape dominated by tea bushes. “The irony is that even with this knowledge, there is no official protection for the tree,” they write, “and it could legally be cut if the correct permissions are sought.” They note that, across their study area, many sacred groves had been reduced to just a solitary tree — most commonly a fig tree.

In India’s urban areas too, the loss of wildlife-friendly trees is elevating the importance of surviving fig trees. In a new study, Harini Nagendra and colleagues documented 5504 trees at religious sites— 62 temples, churches and Hindu, Christian and Muslim cemeteries — in Bengaluru (Bangalore).

Compared with trees in the city’s parks and streets, the trees at religious sites were far more likely to be native species, which offer more to local biodiversity. As in the tea plantation, fig trees (Ficus species) are disproportionately important in urban areas as they feed so many birds and mammals, and at least one fig species was present at 71% of the religious sites the researchers surveyed.

“Fig trees play a critical role in supporting Bangalore’s threatened biodiversity,” says Nagendra. “Bangalore’s tree cover is extremely fragmented, and Ficus trees act as keystone species, improving canopy-to-canopy connectivity and supporting a wide range of species, including birds, butterflies, bees, bats, macaques, and even the endangered slender loris.”

The researchers found 286 individuals of just one fig species — the banyan, Ficus benghalensis — at the religious sites, where it was the fourth most common tree species. But in the city’s streets and parks, all species of fig trees were relatively rare. None ranked in the top ten species the researchers counted there. Nagendra and colleagues says the large numbers of Ficus trees in sacred sites “demonstrate a strong potential” for urban conservation.

“Unfortunately, there is no policy to promote the planting or fig trees, or to conserve them,” Nagendra told me. “Many Ficus trees in Bangalore are heritage trees, decades and even centuries old. Yet many are now under threat, their branches pruned, the bases concreted, or are cut down for road expansion projects.”

In fields and cities in India and all across the tropics, fig trees play key roles in sustaining wildlife. The ecological importance of these trees results from their 80-million-year old relationship with their pollinator wasps, and it helps explain why fig trees have become embedded in religions in many countries.

Over millennia, diverse cultures have protected fig trees but few societies today value them in the same way. Yet, with the right policies in place, these trees could help us to address 21st century challenges — from conserving biodiversity to restoring forest cover.

Tarsh Thekaekara is a biodiversity conservation researcher with The Shola Trust. Shruti Agarwal worked with The Shola Trust before joining the Centre for Science and Environment in Delhi. Harini Nagendra is a professor of sustainability at Azim Premji University, Bengaluru.

Read more about the many ways fig trees have shaped our species and the world about us in my book, published in the UK as Ladders to Heaven: How fig trees shaped our history, fed our imaginations and can enrich our future, and in North America as Gods, Wasps and Stranglers. Readers in India can buy the book here.

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Related posts

The majesty and mystery of India’s sacred banyan trees

Why one fig tree in the middle of nowhere has a 24-hour armed guard

Fresh evidence of the power of fig trees to sustain wildlife and restore lost forests

Photo credit

A fig tree (Ficus religiosa) alongside a Hindu temple dedicated to the monkey god Hanuman in Bengaluru (Bangalore) — Anoop Negi (reproduced with permission). See Anoop Negi’s website for more images.

References

Jaganmohan, M. et al. 2018. Biodiversity in sacred urban spaces of Bengaluru, India. Urban Forestry & Urban Greening 32: 64-70. [Read online]

Thekaekara, T. & Agarwal, S. 2018. The Ficus in the Tea: The fight for the lonely atti maram (fig tree). The Indian Express. 22 April 2018. [Read online]

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