March 20, 2013
How Hunting Animals Can Change The Face Of A Rainforest
Lee Rannals for redOrbit.com - Your Universe Online
Researchers from Lund University in Sweden wrote in the journal Proceedings of the Royal Society B that the hunting of animals like primates in these rainforests can cause a reduction in the dispersal of seeds.
“Hunting has a dramatic effect on the composition and structure of the forest, just as logging does, but without felling any trees,” said Ola Olsson, a professor in Lund´s Department of Biology.
The team studied rainforests in Nigeria, where the locals who live there hunt for food. The types of animals hunted in this region include nearly all the mammals, including gorillas and chimpanzees as well as some small species of monkey.
Apes and small monkeys play an important role in seed dispersal in the rainforests because they feed on a variety of fruits. However, as the number of primates declines due to hunting, their role as seed spreaders is also affected. The fewer fruit seeds that are spread, the fewer the number of fruit trees that will grow in the forests. As a result, the researchers anticipate that tree species that rely on wind to disperse their seeds will eventually take over.
The team's study offers no definitive answers as to how the composition of the forest could change over the years due to hunting, but Olsson did say that there could be an increase in bushes and woody vines called lianas, which could have negative consequences for local human populations. Not only are the natives killing off their primary source for meat, but they are also inadvertently destroying other vital food sources as well.
“Many of the trees which have seeds that are dispersed by primates are also important to people, because those who live in the vicinity of the forests gather a lot of fruit and nuts,” Olsson said.
The researchers say that when the specific composition of the tree species changes in the forest, there will be a "knock-on" effect that further perpetuates these processes.
Olsson said he would like to see better protection for nature reserves and national parks as well as better information and education provided for indigenous villagers. According to Olsson, the reason people are hunting these apes is because it provides a cheap and accessible source of protein, and their carcasses can be sold in towns.
“All our study sites are in protected areas, but the protection is insufficient”, he added.
A study published last year in the journal Science found that humans may have also played a role in the loss of Central African rainforests. Researchers from this study theorized that aluminum to potassium ratios in the soil have changed over the past few thousand years due to human activities. Iron tools used to cut down trees and clear areas to plant crops led to higher rates of chemical alternation, helping to explain the sudden shift in weathering patterns some 3,000 years ago.