Loss of Animals Spells Doom for Diversity of Rainforest Trees

We’ve all heard about the rainforest, and how it’s being viciously logged, and quickly having the life sucked from its ecosystem. Over 20 percent of mammals have gone extinct, and 50 percent of bird species have disappeared. Over 3 million square miles of the original 6.2 million square miles are now gone. Now, unfortunately, a new study is finding that there is a significant increase in sapling growth due to the loss of those ever so important animals we hear about. One might wonder why we care about tree diversity, but the rapid sapling growth is choking out the future generations of trees.

“Tree species that use these animals to disperse their seeds have lost the ability to displace offspring far away from the parents,” says study co-author Matteo Detto, of the Center for Tropical Forest Science, Smithsonian Tropical Research Institute. “For this reason these species appear more aggregated or clustered compared to when hunting was not present.”

The study has been investigating a 128 acre (52 Hectares) plot with about 1200 different species of trees. Previously, various animals would disperse seeds out evenly over the forest floor, but now they strictly grow in clumps around their maternal tree.The result, the study shows, has been a small but consistent decline in local tree diversity, an effect the researchers expect will become more pronounced over time.

“Lambir is the richest forest in the whole of the Old World tropics, there’s nowhere else in Asia or Africa that has a forest this diverse in tree species, with some 1,200 tree species growing in an area of about 128 acres [the CTFS survey area],” explains Stuart Davies, director of the Center for Tropical Forest Science and a co-author of the study. “Lambir is a tiny little national park and unfortunately what’s happening in the tropics is that many of these conservation areas have become isolated by agriculture of various kinds. In the case of Lambir it is surrounded by oil palm plantations and by a growing urban population. These isolated conservation areas have no future for surviving if they continue to get hunted in the way they are. The great majority of tree species need vertebrates for their dispersal and most of the big vertebrates are gone.”

The paper “Consequences of defaunation for a tropical tree community,” was conducted by scientists from the Chinese Academy of Sciences, the World Agroforestry Center, and the Center for Integrative Conservation in China; the Center for Tropical Forest Science, Malaysia; the University of Pennsylvania, the Smithsonian Global Earth Observatory, the Smithsonian Center for Tropical Forest Science, the Smithsonian Tropical Research Institute, and the World Agroforestry Centre, Osaka City University in Japan. --John Barrat

Scientists found that almost half of the deforested land was in Brazil. The red areas show where forest cover has reduced by 50% between 2000 and 2005.

Some scientists have predicted that unless significant measures (such as seeking out and protecting old growth forests that have not been disturbed) are taken on a worldwide basis, by 2030 there will only be 10% remaining, with another 10% in a degraded condition. 80% will have been lost, and with them hundreds of thousands of irreplaceable species.

Citiation:

http://smithsonianscience.org/2013/06/decline-in-animals-spells-drop-in-diversity-of-rainforest-trees/

http://www.guardian.co.uk/environment/2008/jul/01/forests.conservation

http://hardsciencenews.com/2013/06/08/loss-of-animals-spells-doom-for-diversity-of-rainforest-trees/