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

AtlanticForestFig-Eaters

“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.

 

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

FigOnTowerCambodia

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)

The empty forest where 100+ bird species are feared extinct

birdsgone

In the latest study to report rapid loss of wildlife, researchers estimate that 106 bird species have disappeared from an area of forest in Mengsong, in China’s Yunnan province.

The air there should be full of bird song: Yunnan lies in the zone where the tropics and subtropics meet and is one of the most biologically diverse areas of the planet.

There’s plenty of high quality habitat too. Amid Mengsong’s villages and paddy fields and plantations of tea and rubber, about 50,000 hectares of natural forest stand tall. Nearly three-quarters of this is protected in a nature reserve, created in 2009. The amount of forest cover has been stable since 1988. If anything, it has increased.

But when biologist Rhett Harrison* and colleagues spent two years looking for the birds in and around the nature reserve, they failed to find more than 40 percent of the species that should be there.

Their study, published this month in the journal PLoS One, rules out disease, habitat loss, predation and climate change as likely culprits. Instead it blames hunting for most of the losses.

Hunting pressure in Mengsong is extremely high, despite the fact that gun ownership has been illegal in China since 1996. In fact, the researchers spotted 59 hunters in just 107.5 hours of looking out for them. They write:

“In addition to people with guns, we frequently encountered hunters employing nets and snares. The use of nets, in particular, indicates that hunters are actively harvesting even the smallest birds, which they barbeque on skewers.”

In 2012, Harrison recorded a similarly rapid loss of wildlife from a forest in Malaysia. He told me he thinks the situation in Mengsong is typical of that “over all of South China and large parts of tropical South-East Asia.”

This raises questions about the value of creating more protected areas if they are not in fact protected at all. In 2010, China, along with nearly every other country, agreed a global conservation target, which said protected areas should be expanded to cover 17% of the planet’s terrestrial area by 2020, and that these areas should be effectively and equitably managed.

“Everyone is focusing on the former part but very few on the latter,” says Harrison. “People need to recognise that there may be a compromise in countries that are already struggling to deliver management of their existing reserves.”

Harrison and colleagues are keen to point out that they do not blame the authorities responsible for Mengsong’s nature reserve, as most of the local bird extinctions happened before it was created.

Nonetheless, what they show is that yet another protected forest is falling quiet with the silence of extinction. When the birds go, it is more than just their songs and calls we lose. The challenge is for us to decide how much loss is acceptable and what we want the word forest to mean.

Related posts:

The near empty forest that proves conservation is failing

Unhappy endlings: What tales of the last days of extinct and dying species can bring to our own story

Photo credits: Wikipedia/Creative Commons (From top left to right: Black-naped Oriole – J.M. Garg; White-crested laughingthrush – Dibyendu Ash; Rufous-necked hornbill – Ujjal Ghosh; Great hornbill – Kalyanvarma). Each of these species is among those the researchers believe to be locally extinct in their study area.

* Disclosure: Rhett Harrison is a friend and former colleague. He is based at the Kunming Institute of Botany, Chinese Academy of Sciences, and the World Agroforestry Centre, East Asia Node.

Reference: Rachakonda Sreekar, R., Zhang, K., Xu, J. & Harrison, R.D. 2015. Yet Another Empty Forest: Considering the conservation value of a recently established tropical nature reserve. PLoS One. Published: February 10, 2015. DOI: 10.1371/journal.pone.0117920

If we cook these tiny wasps, we put the heat on hundreds of other species

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From the wings of tiny creatures hang the fates of hundreds of bird and mammal species, and perhaps even entire rainforests. They are fig wasps and they play a disproportionate role in the grand drama of life on Earth. They shape our own story too because of this. But new research warns that these insects could be “extremely vulnerable” to global warming.

This matters because each of the 750+ species of fig tree (Ficus species) relies utterly on particular species of fig wasp to pollinate its flowers. Without the fig wasps there would be no fig seeds to create the next generation of trees, and there would be no ripe figs for animals to eat.

In the case of any other group of trees this would not be such a big deal, but figs are special. Their pollinator wasps only live for about a day and each wasp species can only lay its eggs inside the flowers of its specific fig partner. So, to keep their pollinator species alive, each fig species needs to produce flowers and figs year-round. This means a year-round supply of food for birds and mammals, and helps to explain why figs feed more creatures than any other trees do (see A job for conservation’s keystone cops).

In the late 1990s, I set out to find out just how many animal species eat figs. The answer is an astounding 1,200-plus species, including ten per cent of all birds and six per cent of all mammals – see Who eats figs? Everybody). That’s the variety of life that stands to suffer in some way if fig-wasps disappear. Now, in a new study in the journal Biology Letters, Nanthinee Jevanandam of the National University of Singapore and colleagues provide a chilling insight into what a warmer world could mean for these wasps.

In a laboratory, they exposed the pollinators of four Ficus species to temperatures between 25°C and 38°C and to a various levels of humidity. The lifespan of all four species fell steadily as the temperature rose. By 36°C, the lifespan of three of the species had fallen to just two hours. In the wild this would give the wasps hardly any time to find a fig of the right species in which to pollinate and lay its eggs. It would hurt both wasp and fig species. This is the Achilles heel of a partnership that has existed for 80 million years. It is here that we might expect to see the relationship break down, with consequences for other species.

This has happened before. In the 1990s, fig-wasps in northern Borneo went locally extinct after a severe drought, and in Florida they disappeared when a hurricane wiped them out. In both cases, fig-wasp populations eventually bounced back — thanks to the fact they can disperse for tens of kilometres in the day or two they live. But a sustained temperature increase — like that which climate scientists predict will be a reality worldwide by the end of the century — is a different matter. As we turn up the global temperature we change the chemistry of life.

I asked Nanthinee whether she thought fig-wasps could adapt to a rise in temperature, either in their physiology or their behaviour — by flying at a cooler time of day for instance. “Fig wasps can produce up to 12 generations in a year in the aseasonal tropics, and so acclimation or genetic adaption is a possibility,” she said. “But more research has to be carried out to ascertain this. As to the possibility flying at different times, it is difficult to predict.”

The wasp species she and her colleagues studied came from distinct branches of the fig-wasp family tree, so they think their results will be relevant to hundreds of other fig-wasp species, the trees they pollinate and the animals that eat their figs. But these little wasps might have surprises in store for us yet. After all, they survived the mass extinction that saw off the dinosaurs, 65 million years ago. They might outlive us too.

Their story is a reminder that we are just new here, and that between our kisses, our fights and our smiles, we tend to stumble about breaking things before we know how they work.

Photo credit:
Valisia malayana fig-wasps at a fig of their host tree Ficus grossularioides (Nanthinee Jevanandam)

Related posts:
The humbling history of the tiny wasps that upset a Jurassic Park narrative.

Reference:
Jevanandam, N., Goh, A.G.R. & Corlett, R. 2013. Climate warming and the potential extinction of fig wasps, the obligate pollinators of figs. Biology Letters 9: X-X.  Published online March 20, 2013 doi: 10.1098/rsbl.2013.0041

A bit naughty? Secret filming exposes murky world of rainforest politics

Global Witness has released footage that exposes the way elites have carved up and sold off the tropical forests of Sarawak in Malaysian Borneo, then siphoned away millions of dollars through illegal tax dodges. Global Witness filmed the footage in secret when one of its team posed as an investor who wanted to buy up land in Sarawak so he could set up oil palm plantations.

The main targets of the investigation are Tan Sri Abdul Taib Mahmud — who has been Sarawak’s Chief Minister for over 30 years and controls access to forests there — and members of his extended family.

“This film proves for the first time what has long been suspected — that the small elite around Chief Minister Taib are systematically abusing the region’s people and natural resources to line their own pockets,” said Tom Picken, Forest Team Leader at Global Witness, in a press release. “It shows exactly how they do it and it shows the utter contempt they hold for Malaysia’s laws, people and environment.”

In Sarawak, the website FZ.com caught up with the Chief Minister today and reported his response to the claims:

“Ok I saw the so called proof. Could it not be someone who tried to promote themselves to be an agent to get favours from me?  It has nothing to do with me. I think it is a bit naughty of them.”

Taib is a master of public relations — as revealed in open letter that The Sarawak Report sent to British reality TV star Ben Fogle after he gushed good publicity about his recent trip to Sarawak. While it is clear that something “naughty” has indeed happened to Sarawak’s forests, Taib seems unconcerned by the latest salvo in an ongoing campaign against him.

Here’s the Global Witness video… The FZ.com interview follows:

Kill off the animals and you change the forest — fast

Last year I brought you the story of Lambir Hills National Park, a Bornean forest in which I used to live and work, where hunting and other pressures have forced into extinction much of the biggest wildlife species (see The near empty forest that proves conservation is failing).

It describes how recent surveys had failed to find 20 percent of the park’s resident bird species and 22 percent of its mammal species. The forest is emptying fast. The losses include half of the park’s primate species and six out of seven hornbill species —  all important dispersers of rainforest seeds. Sun bears and gibbons, bearded pigs and flying foxes all once called Lambir Hills home. Today it is hard to find an animal that weighs more than a kilogram in the national park.

Now researchers have shown what these extinctions mean for the forest itself. Rhett Harrison and colleagues tracked the fates of over 470,000 trees of more than 1,100 species for a 15-year period since intense hunting began there.

In a new study published in Ecology Letters, they have shown that the forest has changed markedly. There are far more trees now — the density of saplings increased by over 25 per cent between 1992 and 2008 — probably because there are fewer deer and other mammals to eat the young plants. But overall the diversity of trees has fallen. And compared to species that rely on gravity or wind to spread their seeds, there has been a relative decline in the number of new trees from species that depend on animals to disperse their seeds.

Species with animal-dispersed seeds — especially those with bigger seeds — are also more clustered than they were before hunting took off. This is probably because the loss of large fruit-eating animals means that seeds, on average, now travel shorter distances. There was no increase in clustering among species that need no animal assistance to spread their seeds.

The author’s write: “Fruit that would formerly have been eaten by hornbills, gibbons or fruit pigeons, all of which are efficient long-distance seed dispersers, are now unlikely to be fed on by anything larger than a bulbul or a barbet”. For those of you who don’t know the birds of Borneo, members of the latter two types are both small enough to fit in a trouser pocket.

The researchers could draw their conclusions because Lambir is home to one of the world’s longest running forest studies. In 1992, scientists marked out a 52 hectare patch of the forest and then tagged, measured, mapped and identified every tree bigger than 1 cm diameter at breast height. In 1997, 2003 and 2008 they went back and repeated the exercise, each time taking several months to complete the task.

Their massive datasets, which track the identity and positions of around half a million trees every 5-6 years can animate the forest’s history. Like the photographs that form time-lapse videos, these periodic census snapshots reveal the patterns of life over time.  The next census of the 52-hectare plot, which is due to take place soon, will add a critical fifth image that further refines the picture of a forest in flux.

The results are already striking but, as the authors note: “the full impacts of defaunation at Lambir are only likely to be realised over several plant generations.” So far, none of the species that depends on big animals to disperse its seeds has gone extinct. That’s just a matter of time.

Reference:

Harrison, R. D. et al. 2013. Consequences of defaunation for a tropical tree community. Ecology Letters. Article first published online: 12 MAR 2013 DOI: 10.1111/ele.12102

In under three minutes, a year in a forest

Samuel Orr has been good enough to publish online this time-lapse video he shot from a house in a nature reserve near Bloomington, Indiana. He stitched it together from 40,000 images he took over a 15-month period. It’s a wild and beautiful place. On his website, Orr says: “I’d often look out the window and see turkeys, deer, flying squirrels, vultures, possums, huge orb weaving spiders, and a dizzying array of songbirds and woodpeckers.”

The result is a stunning portrait of the seasonal cycles that breathe life through every layer of the forest — and the soundscape is a rich as the view. Here Orr describes creatures we can hear.

“I tried to put in wildlife songs and calls appropriate to the season.  For instance, the honking during what is late winter are Sandhill Cranes, which used a migratory flyway that passed directly overhead.  Many of the calls were recorded on sight, others were from elsewhere in Indiana.  Animals heard include migratory songbirds, spring peepers, tree frogs, cicadas (periodical and annual), turkeys, coyotes, elk, and wolves.  While there are no wild wolves or elk native to Indiana anymore, but for hunting long ago they would still roam the surrounding hills.  Maybe they’ll be back some day.”

You can read more about his work at Motionkicker.com