For example, guapeva-vermelha, a tree endemic to Brazil and listed as “vulnerable” under the IUCN, depends on animals such as the brown howlers, southern muriqui monkeys, and the South American tapir to disperse their seeds. Unfortunately, as these animals were killed or chased out of their habitat, the P. bullata vanished as well.
“Seed dispersal is a complex process involving many types of vertebrates at the same time. Deforestation leads to the extinction of animals, which lose food, and plants, which can no longer disperse their seeds,” explained study first author Lisieux Fuzessy.
When the researchers began to explore seed dispersal in the Atlantic Rainforest, they didn’t realize they would be digging so deep into vertebrate seed dispersal.
“We set out initially to investigate the role of primates in seed dispersal, but it soon became evident that we needed to analyze the roles played by all vertebrates,” said Fuzessy.
The team decided to complete a wide-ranging analysis of seed dispersal. They examined the role of primates, birds, bats, carnivores, marsupials, rodents, and ungulates in this critical process.
The researchers focused on two forests. One was Serra de Paranapiacaba, which includes 120,000 hectares of highly preserved forests. The area contains elusive jaguars, bush dogs, the white-lipped peccary, and a large frugivorous bird known as the black-fronted piping guan. The researchers documented 1,588 interactions between 133 animals and 315 plants in Serra de Paranapiacaba.
The second study area was Reserva de Santa Genebra. This forest is only 250 hectares, fragmented, and surrounded by human disturbance. The area was also heavily deforested before it gained protected status in 1984. Most of the animals in Reserva de Santa Genebra are notably smaller. The animals found here include the spotted paca, American opossum, and the Brazilian squirrel. Here, researchers recorded 21 interactions between 54 animals and 58 plants.
“The difference was highly significant. Key species such as muriquis and tapirs eat a far greater diversity of fruit than birds, for example,” said Fuzessy. “In addition to their strong demand for calories, they have a wide gape or gullet, which enables them to swallow large fruit and disperse plants that without them simply disappear in a cascade effect.”
The results of the study further illustrate that species conservation is not enough. When considering reforestation projects, conservationists need to analyze the ecology of an area and aim to conserve functional diversity.
The study is published in the journal Biotropica.