Fake fruits could help restore rainforest
Bats lured by foam food bring seeds to patchy land.
Bats can be lured into large areas of destroyed rainforest with fake fruits, researchers have found. This, they say, could be the key to restoring patchy parts of the landscape.
South American leaf-nosed bats of the family Phyllostomidae defaecate the seeds of the fruits they have eaten as they fly. This process, known as 'seed rain', aids plant dispersal throughout the rainforest.
Gledson Bianconi of the Universidade Estadual Paulista in Rio Claro, Brazil, along with a team of ecologists and chemists, wondered if this efficient seed-dispersal mechanism could be harnessed to restore damaged parts of the rainforest. If bats could be controlled, they thought, they could perhaps be used by researchers aiming to regenerate parts of the forest that had been used as agricultural land or pasture until the topsoil washed away.
The team extracted the essential oils of peppers (Piper gaudichaudianum), a favourite meal of some species of leaf-nosed bats, and smothered them on artificial fruits made of foam rubber. They then placed these fruity lures in the midst of damaged rainforest, where bats would not normally bother to fly in search of food.
They staked out the forest by night, and waited to see if bats would be tricked into visiting the area. Using night-vision goggles, they saw up to a dozen bats come out of the denser rainforest each night to visit the fruit.
But the team also needed to know if these bats would be effective at distributing seeds — it was possible that only very hungry bats would bother to chase down the fake fruit, and that these bats would have no seeds to deploy. The team trapped the bats using nets, and collected their faeces. Inside they found plenty of seeds, they report in Biotropica1.
Rainforests house much of the world's biodiversity, and play a major role in mitigating climate change by capturing carbon, so researchers are keen to reverse the damage done by the widespread deforestation that has taken place over the past century.
Many restoration projects involve planting a mixture of native plants along with more exotic pioneer species, which are better able to deal with the relatively harsh conditions of exposed land. But this creates a landscape very different from the pristine rainforest that conservationists would like.
"Most reforestation projects cannot plant many native rainforest plants because they do not have them available," says team member Sandra Bos Mikich of the ecology laboratory of the Brazilian Agricultural Research Corporation (Embrapa), Colombo, Brazil. For many of these plants, seedlings are not commercially available owing to the difficulty of growing them; for some, the seeds need to be digested before they can germinate properly.
Using the essential oils of fruit to attract bats for seed dispersal, she explains, would be an easy way of increasing the flow of native seeds to the area, and of ensuring a high diversity in the forest.
"This research may provide a nice way of reintegrating native rainforest plants into damaged areas," agrees tropical botanist Bente Klitgaard of the Natural History Museum in London. The tough question is whether those native plants will be able to survive in the harsh dryness, heat and bright sunlight that comes with open land.
All such strategies also need to compete with alternative uses for the land - such as using it to farm crops. "It would be ideal if we could only regenerate 'real rainforest', but we have to be realistic," says Klitgaard. "We have to be able to feed people too."
Mikich and her team now plan to identify the components of the oils that are responsible for bat attraction, so they can synthesize them and make this technique of forest regeneration more widely available.
- Bianconi G.V, Mikich S.B., Teixeira S.D. & Maia B.H.L.N.S Biotropica, 39. 136 - 140 (2007).