Stanford, CA Tropical plants are able to adapt to environmental change by extracting nitrogen from a variety of sources, according to a new study that appears in the May 7 early online edition of The Proceedings of the National Academy of Sciences.
By demonstrating that not all plants specialize in one specific source of nitrogen, the result turns a commonly held theory on its head. It also provides a dose of optimism that tropical forests will be able to withstand environmental shifts in nutritional cycles brought on by global climate change.
Nitrogen is an essential nutrient that plants must absorb from the soil to survive. Most land plants outside the tropics appear to have evolved to rely on just one of three common sources of nitrogen: nitrate (NO3-), ammonium (NH4+), or dissolved organic nitrogen (DON). As a result of this limitation, they usually inhabit "niches" defined largely by the available nitrogen source. When that source crashes for any reasonoften because of shifts in climatethe plants cannot adapt, with potentially disastrous consequences for natural ecosystems.
However, tropical species appear to be far more adaptable than their temperate kin when it comes to their nitrogen needs. A team of researchers* has found that, when confronted with shifts in nitrogen availability, these plants simply "flip a switch" and use whatever is handy.
"When it comes to nitrogen, the tropical plants we studied behave like kids at a pizza partythey may prefer pepperoni, but if only plain cheese is available, they'll still have a slice," said lead author and postdoctoral researcher Benjamin Houlton of the Carnegie Institution's Department of Global Ecology. "This result gives a glimmer of hope that tropical ecosystems may have the capacity to adjust to certain aspects of climate change."
Working in six well-known sites with variable rainfall on Hawaii's Maui Island, the researchers measured the soil content of nitra
Contact: Dr. Benjamin Houlton