The lush Amazon Basin is currently wetter than any other time on record, a study printed on Friday the 22nd December in the international journal Science reveals.
The rainfall history of the Amazon Basin since the ice ages is important for a number of questions, such as whether arid conditions reduced or fragmented the rainforests, how the tropics contribute methane to the atmosphere, and how tropical climate may have affected the global water cycle.
Francis Mayle of the University of Leicester Department of Geography and colleagues Rachel Burbridge and Timothy Killeen used pollen analysis to examine the long-term dynamics of forest-savanna boundaries in southern Amazonia, which are extremely dependent on climate patterns.
Mayle’s team found that the forest in Bolivia currently stretches farther south than at any other time in the last 50,000 years, and that the rainforest communities at this southern boundary may be less than 3,000 years old.
Mayle said: “Our evidence for increased southerly expansion of Amazon rainforests at 3,000 yr BP can be explained by increased annual rainfall at this time, which can in turn be explained by increased summer solar radiation in the Southern Hemisphere caused by changes in the Earth’s orbit about the Sun.
“Furthermore, our findings suggest that the young rainforest communities at the southern margin of Amazonia are less biodiverse than more central parts of Amazonia because they are still undergoing succession and have not yet reached ‘biodiversity saturation’.
“Clearly, the age of rainforest communities needs to be established and taken into account when seeking explanation for regional differences in biodiversity within Amazonia.”
The Leicester research project was funded by the University of Leicester, The Royal Society, and the Natural Environment Research Council.
NOTE TO NEWSDESK (not for publication):
For more information, please contact Dr Mayle on the following numbers 0116 270 7568/ 0116 252 3831.
This document has been approved by the head of department or section.
If you are an authorised user you may edit this document through your Web browser.