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.

 

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