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

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“Who eats figs? Everybody,” wrote tropical biological Daniel Janzen in 1979. He meant that in tropical rainforests most, if not all, fruit-eating animals will consume figs — the false-fruit of the 750+ Ficus species — at some point in their lives. When I tried to quantify this two decades later, I found records of more than 1270 bird and mammal species eating figs. No other kinds of fruit sustain so much wildlife.

One reason for this is that, unlike most fruit, figs can be found year round. Ficus species therefore sustain birds and mammals through times of general fruit scarcity. As these animals disperse the seeds of thousands of other plant species, the fig trees are crucial to the health of tropical forests.

As my new book shows, research in forests in Africa, Asia and the Americas has shown that without figs, many species of wildlife would suffer, with severe knock-on effects for the plants and animals around them. The flip-side of this is that planting fig trees can boost biodiversity and encourage rainforests to regenerate in areas that have been logged. Efforts to do this are underway in Thailand, Costa Rica and Rwanda.

Now new data published by Carolina Bello and colleagues in the journal Ecology hints that this approach could be valuable in one of the world’s most threatened but least famous forests: the Atlantic Forest of South America.

The Atlantic Forest’s diversity rivals that of the Amazon, but it is in a far more parlous state. The forest once covered an area twice the size of Texas, covering parts of Brazil, Paraguay and Argentina. Today 85 percent of it has gone. Many of its plants and animals face extinction.

Conservationists are trying to reverse the damage. The Pact for Atlantic Forest Restoration, for instance, aims to restore 15 million hectares of forest there by 2050. The newly-published dataset suggests fig trees could play an important role in such efforts. It gathers thousands of records, made over 55 years, of fruit-eating by animals in the Atlantic Forest. It includes interactions between 331 animal species and 788 plant species.

I had a quick look at the data to see if the forest’s figs were important resources. Indeed they are. The 28 Ficus species represent just 3.5 percent of all plants in the database but, together, they have so far been recorded in the diets of one-third of the fruit-eating animal species (29.7 percent of birds and 43.3 percent of mammals).

That may seem like a lot but it’s a highly conservative estimate. More than half of the fruit-eating animal species in the dataset are either endangered or critically endangered – which makes it hard to study their diets. I would bet that nearly every single one of the Atlantic Forest’s fruit-eating species eats figs.

With figs appearing year-round, this is good news for the other plant species whose seeds these animals disperse. In the new dataset, the fig-eating animals of the Atlantic Forest have been recorded eating the fruit of 691 other plant species. That’s 91 percent of the remaining plant species.

Ficus species appear to be hugely important to the Atlantic Forest. Planting fig trees could therefore accelerate efforts to restore this unique ecosystem as figs attract and sustain the seed dispersers of so many other species.

Reference: Bello, C. et al. 2017. Atlantic frugivory: a plant–frugivore interaction data set for the Atlantic Forest. Ecology. doi:10.1002/ecy.1818

Photo credits: Fig-eating animals of the Atlantic Forest include: Tent-making Bat (CharlesJSharp); Golden-headed Lion Tamarin (Hans Hillewaert); Toco toucan (CharlesJsharp); Northern Muriqui (Peter Schoen); Magpie Tanager (Francesco Veronesi); Blue Dacnis (Andreas Trepte); Violaceous Euphonia (Dario Sanches) – all Wikiepedia/Creative Commons.

 

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Amazing photo of Buddha’s head engulfed by strangler fig roots

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Few photographs have captured the biological and cultural splendour of fig trees better than this fantastic shot by Adam Baker of strangler fig roots engulfing a stone carving of the Buddha’s head at Wat Mahathat, a 14-century Buddhist temple in Ayutthaya, central Thailand.

Strangler figs grow across the tropics and subtropics, starting out in life high on other trees and sending down aerial roots that merge and split and merge again, dominating all that they encounter. These awesome, eerie plants have become embedded in religion and culture wherever they grow.

It was while meditating beneath a strangler fig that the Buddha attained enlightenment. Throughout Asia, Africa, the Pacific and parts of the Americas, these plants are homes to gods and spirits, places of prayer and ritual. But they are also ecological linchpins, sustaining more species of wildlife than any other trees.

My book —published in the UK as Ladders to Heaven and in North America as Gods, Wasps and Stranglers tells how fig trees have shaped our world, influenced diverse cultures and can help us restore life to degraded rainforests. Read a summary here.

Credit: I’ve reproduced Adam Baker’s photo with his permission. Check out the original and his other great photography on Flickr.

The magic of tropical forests and the fig trees that live in them

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Michael Metivier at my US publisher Chelsea Green Publishing (CGP) recently interviewed me about my book — published in the UK as Ladders to Heaven and in North America as Gods, Wasps and Stranglers. The book is about how fig trees have influenced humanity and the world about us in profound ways thanks to some extraordinary biology.

Here’s how the conversation went:

CGP: You’ve written a fascinating book about figs, but your interest in biology started with big animals. How did you end up finding figs and fig-wasps?

MS: What interested me most when I began studying biology at university was how animals and plants behave and interact and influence each other’s fates. But I was definitely more interested in animals than plants, and in big animals more than small ones.

By accident, I ended up studying the whole gamut in the mixed-up biology of fig trees, their pollinator wasps, and seed-dispersing birds and mammals. For my master’s degree’s field project, I was meant to go to Indonesia to study the wild bird trade, but it turned out that the project there needed a social scientist, not a biologist.

My course supervisor felt bad and reached out to three of his fellow fig biologists to see if any could host a project student for six weeks. It was Rhett Harrison, in a rainforest national park in Borneo, who replied first with a yes. The fig trees I studied there soon seduced me. My master’s project turned into a doctoral thesis, and I would spend 18 months in the rainforest over the next three years.

CGP: What do you mean by “mixed-up biology of fig trees.” Can you elaborate?

MS: By mixed-up I meant that the fates of fig trees, fig-wasps, and fig-eating birds and mammal are all bound together. The flowers of each fig tree species can be pollinated only by specific fig-wasp species. The wasps in turn can only breed in their partner’s flowers, which are inside the figs.

Thanks to this 80-million-year-old relationship, more than 1,200 bird and mammal species benefit by feeding on ripe figs. And because of the wasps, ripe figs can be found year round, sustaining a great variety of wildlife when other fruits are scarce. Most of these animals are fig-seed dispersers, providing a service to the fig trees in return for a payment of fig flesh.

The wasp-fig-wildlife marriage is under constant pressure. Some birds and mammals are enemies of the fig trees, destroying the seeds they consume. There are also parasitic insects that feed on the offspring of pollinator wasps inside their figs. Overall though, the marriage is strong. It has many children too—not only the new generations of fig trees, fig-wasps and fig-eating animals, but also those of hundreds of other plant species whose seeds the fig-sustained animals disperse. As a result, fig trees and their associated animals shape the world about us, just as they have been doing for tens of millions of years.

CGP: You grew up off the coast of England, so what began your fascination with tropical ecosystems, and what/when was your first encounter with them?

MS: I grew up on Jersey, a very small island in the English Channel, with no rivers, no mountains, no forests. My interest in tropical forests was fed in part by my dad’s love of nature and being outdoors. Under his influence, I also watched a lot of David Attenborough documentaries as a kid.

Another big childhood influence was Jersey Zoo, now Durrell Wildlife Park, and its symbol—the dodo. The writer Gerald Durrell had set the zoo up to breed rare species and restock their wild populations. At a very young age, the zoo taught me about the diversity of life, the wonders of the tropics, and the reality of extinction.

Later when I was a teenager, I began reading New Scientist and started to understand just how important tropical rainforests are, not just for wildlife but for the climate and our wellbeing. The first time I went to the tropics was in 1994, when I visited Sri Lanka with some friends from university. To walk in a tropical forest for the first time was an amazing experience. I was awestruck.

CGP: You clearly identify the ecology and biology of fig trees, but you’ve become fascinated with the role figs have played in human history. What can we learn from these cultural associations and meanings?

MS: The more I learned about wild fig species, the more I came across curious stories in which these trees star. They feature in myths and religious stories from places as varied as Greece, Kenya, Mexico, Egypt, India, and Australia—and many more. The local Iban people who lived near my research site in Borneo said strangler figs were hosts to spirits and so should never be felled.

I later learned that such taboos against felling fig trees are remarkably common to diverse cultures around the world. The more I dug, the more I realised how deep-rooted fig trees are in the human story. They were sustaining, protecting, and inspiring our ancestors long, long ago, and today, thanks to their unique biology, they can help us to restore damaged rainforests and protect rare and endangered wildlife.

Protecting and planting fig trees will help us to safeguard many thousands of other species of plants and animals and the ecological functions they provide. Healthy biodiverse forests can both provide sustainable livelihoods and lock away carbon, slowing climate change. Those ancient cultural taboos against felling fig trees are still relevant today.

CGP: One of the lasting impressions from your book is the surprising ways in which science and spirituality quite naturally intertwine. On a personal level, is there a memory you have from your travels and studies where you experienced the sublimity of these connections?

MS: The first time I walked in a tropical rainforest, in Sri Lanka in 1994, I felt what I can only describe as awe. I viscerally felt the abundance of life all about me. It was as if I could somehow detect it at some deep level within me. To be in a tropical rainforest is to be immersed in a new atmosphere, a different humidity, a new soundscape, and a visual flood of myriad shades of green.

With so much life vibrating in one place, it is hard not to feel some connection to the rhythm. I have had that same sensation many times in Borneo and in the Amazon and in other forests. Part of its power is how it reveals that all life is connected, and how small we are in the greater scheme of life. The sensation is both grounding and enlivening.

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More information

Ladders To Heaven: How fig trees shaped our history, fed our imaginations and can enrich our future was published in the UK by Unbound.

Gods, Wasps and Stranglers: The Secret History and Redemptive Future of Fig Trees was published in North America by Chelsea Green Publishing.

While the titles are different, the content of these two books is the same.

Read a summary and advance praise from Annie Proulx, Deborah Blum, Michael Pollan, Sy Montgomery, Fred Pearce, Simran Sethi and Thomas Lovejoy and others.

Photo credit: Lawrence Murray (Flickr / Creative Commons) – cropped image of strangler fig on ruined temple (Beng Mealea, Cambodia)

Radio interview: How fig trees shaped our world, changed history and can enrich our future

Figs and fig wasps (Photo: Jnzl’s Photos, Flickr CC BY 2.0)

Public Radio International’s environmental news show Living on Earth has interviewed me about my new book, which tells how fig trees have shaped our world, influenced diverse cultures and can help us restore life to degraded rainforests. The book is published in the UK as Ladders to Heaven and in North America as Gods, Wasps and Stranglers.

You can listen  below or vist Living on Earth’s website for a full transcript and photos.

Visit this page for more information about the book and advance reviews from Annie Proulx, Deborah Blum, Michael Pollan, Sy Montgomery, Fred Pearce, Simran Sethi and Thomas Lovejoy and others.

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Photo credit: Jnzl’s Photos, Flickr CC BY 2.0

Magical trees, living bridges and a human butterfly

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I’ve had a busy few weeks of writing. Here are intros and links to five articles I have had published in December.

Scientific American: The nearly magical properties of fig trees

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.

*Read the full article here.

ChinaDialogue: Biodiversity talks end with slew of announcements

Intergovernmental negotiations under the UN Convention on Biological Diversity (CBD) in Cancún, Mexico ended with a slew of decisions aimed at safeguarding nature, ensuring natural resources can be used sustainably, and that the benefits are shared fairly and equitably.

*Read on in English, Chinese or Spanish

Thomson Reuters: Can living fig-tree bridges save lives in a changing climate?

In 1841, a young Scotsman called Henry Yule was exploring the Khasi Hills of north-east India when he came upon something no other European had ever reported. There, in that challenging landscape of thick rainforest and perilous gorges, was a most extraordinary structure — a living bridge formed from the roots of a gnarly old fig tree.

*Read the full article here.

BBC Earth magazine: The human butterfly

High on a sea cliff on the Hawaiian island of Kauai grows a strange and very special plant. Its grey stem is swollen at its base to conserve water. Atop the stem sits a rosette of shiny green leaves. “It sort of looks like a cabbage on a bowling pin,” says Steve Perlman, the botanist who has repeatedly risked his life to save it from extinction. Its name is Brighamia insignis, and it’s a species with many problems.

*Read the full article in the December edition of the magazine.

New Scientist: Tree of life – How figs built the world and will help save it

Their leaves clothed Adam and Eve; their roots were used by the Maasai people’s god to shuttle the first cattle from heaven to Earth; and according to an Indonesian story, two gods carved the first couple from their wood. The presence of fig trees in numerous origin myths is down to more than coincidence. They have shaped our world since long before the dawn of humanity, and have fed us and our imaginations for millennia. Now, as the world warms and forests fall, these extraordinary trees could help us to restore life to deforested landscapes.

*Read the full article here or in the print edition.

 

Can living fig-tree bridges save lives in a changing climate?

By AditiVerma2193 (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

In 1841, a young Scotsman called Henry Yule was exploring the Khasi Hills of north-east India when he came upon something no other European had ever reported. There, in that challenging landscape of thick rainforest and perilous gorges, was a most extraordinary structure — a living bridge formed from the roots of a gnarly old fig tree.

The tree’s roots had somehow reached more than 20 metres across a river and taken hold on the far side. Over time, they had thickened and interwoven to form a walkway, onto which Yule now had to step. One of the roots, which in places was thicker than his thigh, provided a handrail. Side roots had descended from it and merged into the walkway, making the whole structure strong and secure. Yule could cross with confidence.

The bridge was no miracle. Long before, human hands had guided the tree’s roots across the river, training them into a shape that could promise safe passage. Yule had assumed the bridge to be “unique, perhaps half accidental”, but he soon saw several more. Their architects were local Khasi people, whose attitudes towards time, the environment and their unborn descendants we are sorely lacking in our fast-warming world.

Fig tree bridge. Credit: Laurence Mitchell (https://eastofelveden.wordpress.com/2011/03/06/crossing-the-bridge/)

The Khasi Hills are in Meghalaya, an Indian state whose name means ‘land of the clouds’. The clouds cry often on this land, for nowhere else on Earth must people endure such heavy rainfall. Twelve metres of it falls in a typical year. After monsoon rains, the region’s rivers rise. The rush of water racing downstream renders steep gorges impassable, isolating villages and endangering lives. Yet people have lived in the Khasi Hills for at least 3200 years. For generations, they have overcome this extreme environment by harnessing the strong yet pliant roots of Ficus elastica, a fig species best known as the Indian rubber tree.

Fig roots are exceptional. They grow fast, long and strong. They can even rip apart bare lava and concrete. In many fig species, including Ficus elastica, the roots aren’t all underground. These figs produce aerial roots that flow down their trunks and drop from their branches. Their roots can merge and split and merge again, forming strong, mesh-like structures. Long ago, the Khasi people worked out how to get such fig roots to do their bidding.

It’s a practice still alive today. The Khasi and neighbouring Jaintia peoples have shaped fig roots into living ladders, whose rungs ease journeys up steep slopes. They have woven the roots into nets that hold banks of earth in place, preventing landslides and soil erosion. They have even forced fig roots to form a platform, from which to watch football games. But the masterworks of Khasi architecture are their bridges. Most — like one Yule sketched, below — form from the roots of two fig trees, one on either side of a river. The longest spans more than 50 metres, the oldest an estimated 500 years.

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Building these bridges involves first guiding slender fig roots through hollow trunks of betel palms, which support, nourish and protect the roots as they lengthen. Once the fig roots are long and strong, the bridge builders bind them to those of the opposing tree or embed them in the ground on the far side of the river. They shape secondary roots that grow from these mainstays into a net that will form a walkway. They use stones and soil to plug any gaps then wait for the roots to thicken and hold everything in place.

It can take 15-30 years before the bridge is strong enough to use. But in Khasi time this is an eye-blink. The Khasi people are investors in the future. People living there today benefit from the ingenuity and foresight of their ancestors and today’s bridge builders bequeath security to future generations. The fig tree bridges don’t only make commerce and romance possible between otherwise isolated villages. They also save lives. As the climate changes, this ancient approach to bioengineering has never been more relevant.

Meghalaya was already the wettest place in the world when Henry Yule explored its forested hills in 1841. Back then, the atmospheric concentration of carbon dioxide was 283 parts per million. Today it is more than 400. More carbon means warmer air, and as warmer air carries more moisture, this means more rain. The state government’s climate change action plan says rainfall has increased in most districts of Meghalaya in the past century, with the highest increase in the West Khasi Hills. It warns that as temperatures continue to rise, so will rainfall and the risk of floods and landslides.

To architect Sanjeev Shankar, these threats call for renewed attention to living bridges. In a research paper he presented in 2015, he warned that they are being replaced by “inappropriate solutions”. Quick-fix bamboo bridges buckle and break – they can’t withstand the monsoon rains. People have died as a result. Modern steel bridges corrode, their cables weaken and snap. And because repairs are rare, these bridges last just 40-50 years compared to hundreds for living bridges.

Shankar says the living fig bridges cost next to nothing and become stronger, more robust and resilient with time and use – unlike expensive, short-lived steel suspension bridges. Indeed, some of the bridges Henry Yule saw in the 1840s are still saving lives today. Shankar urges a revival of fig-tree bridge-building, and even foresees bridge that are strong enough for vehicles to cross.

The only downside is the time it takes the bridges to grow. But Shankar sees potential to blend the old with the new. Having seen how Khasi people have used fig roots to mend steel bridges, he envisages planned hybrid structures — steel bridges that fig trees envelop with their roots and make stronger. Shankar wonders if other fig species could perform this role in other countries, helping people adapt to the changing climate.

The question is, will there be time? It’s a question for us all, as climate change doesn’t respect the short-term thinking that tends to rule our lives. The Khasi people’s approach is instructive. To build living bridges, they invest time and effort knowing they might not personally benefit but that their children surely will. Such foresight, patience and selflessness is rare.

This post was first published by the Thomson Reuters Foundation and is reproduced here with permission.

IMAGE CREDITS: Top (Aditi Verma, via Wikimedia Commons); middle (Laurence Mitchell); bottom (Henry Yule, from Yule, H. (1844). “Notes on the Khasia Hills, and people”. Journal of the Asiatic Society of Bengal. 14 Part 2, Jul-Dec (152): 612–631).

My new book —published in the UK as Ladders to Heaven and in North America as Gods, Wasps and Stranglers tells how fig trees have shaped our world, influenced diverse cultures and can help us restore life to degraded rainforests.

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A great month for a book about fig trees

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It has been an eventful month for my new book. Published in the UK as Ladders to Heaven and in North America as Gods, Wasps and Stranglers, it tells how fig trees have shaped our world, influenced diverse cultures and can help us restore life to degraded rainforests.

This week BBC Radio 4’s Food Programme featured it in its annual review of new food-related books. Author Alex Renton called it: “A lovely little book, a real pleasure”. You can listen to the show here.

Earlier in the month, on WHYY public radio in the United States, broadcaster Mike McGrath said: “My mind has been blown… Absolutely wonderful… My book of the year”. You can listen to the full show here (I’m on from about 14 minutes, 10 seconds).

Also this month, Marion Nestle of Food Politics called it “a truly informative book”, and Donna Seamen of Booklist called it “lively… mind-expanding… richly entertaining and truly enlightening”.

In other news, I learned a few days ago that the first translated edition of the book will come out in 2018, in Turkish, through Istanbul-based publisher Nail Kitabevi.

I have also been busy with interviews. Last week, Erik Hoffner at Mongabay.com opened with a question about the virtues of strangler figs and ended up asking about robots in rainforests.

Along the way we talked about why figs are so important in rainforests, whether figs will endure climate change or help us to limit it, and what is special about strange shaggy animals called binturongs. I started by explaining why strangler figs are trees of life, not death. You can read the full interview here.

And, if you are in the USA, you can listen this week to a new interview by Lynne Rossetto Kasper for The Splendid Table, a food and culture show broadcast by American Public Media. It airs on Friday 2 December, and will be available online as a podcast after that.

I am learning just how hard it is to market a book, but that every little bit of publicity helps. So, if you have already read my book, I would be very grateful if you would consider leaving a rating at Amazon (US or UK) and/or Goodreads.