Princeton-led team finds secret ingredient for the health of tropical rainforests

Princeton University: A team of researchers led by Princeton University scientists has found for the first time that tropical rainforests, a vital part of the Earth's ecosystem, rely on the rare trace element molybdenum to capture the nitrogen fertilizer needed to support their wildly productive growth. Most of the nitrogen that supports the rapid, lush growth of rainforests comes from tiny bacteria that can turn nitrogen in the air into fertilizer in the soil.

Until now, scientists had thought that phosphorus was the key element supporting the prodigious expansion of rainforests, according to Lars Hedin, a professor of ecology and evolutionary biology at Princeton University who led the research. But an experiment testing the effects of various elements on test plots in lowland rainforests on the Gigante Peninsula in the Barro Colorado Nature Monument in Panama showed that areas treated with molybdenum withdrew more nitrogen from the atmosphere than other elements.

"We were surprised," said Hedin, who is also a professor in the Princeton Environmental Institute. "It's not what we were expecting." The report, detailed in the Dec. 7 online edition of Nature Geoscience, will be the journal's cover story in its print edition.

…The discovery has implications for global climate change policy, the scientists said. Previously, researchers knew little about rainforests' capacity to absorb the greenhouse gas carbon dioxide. If molybdenum is central to the biochemical processes involved in the uptake of carbon dioxide, then there may be limits to how much carbon that tropical rainforests can absorb….

Electron shell diagram for Molybdenum, the 42nd element in the periodic table of elements, created by Pumbaa (original work by Greg Robson), Wikimedia Commons, under Creative Commons Attribution ShareAlike 2.0 England & Wales (UK) Licence