Each tropical tree species specializes in getting the nutrients it needs

[Judi Lynn]

Date:
August 3, 2018

Trees communicate via a "wood wide web" of roots and microbes in ways that enhance their growth and can reduce carbon dioxide in the atmosphere, mitigating climate change. But no one knows why so many tropical trees team up with bacteria to capture nitrogen from the air when they already grow in nitrogen-rich soils. A super-sized experiment at the Smithsonian Tropical Research Institute (STRI) to address this paradox showed that each species has its own unique nutrient-capture strategies, underscoring the importance of biodiversity for successful reforestation projects.

Tropical soils may be rich in nitrogen, but poor in phosphorus useable by plants. Many tropical tree species -- usually in the bean (legume) family -- have nodules on their roots formed by bacteria to capture nitrogen gas from the air and convert it into nitrogen useful for growth and carbon storage.

"People speculated that nitrogen-fixing species might channel extra nitrogen into making the phosphatase enzyme to capture phosphorus," said Jefferson Hall, director of the Smithsonian's Panama Canal watershed experiment -- the Agua Salud Project. "But the evidence was limited."

Hall and colleagues realized that the landscape-scale experiment designed to find out how tropical trees store carbon, affect the water supply and conserve biodiversity, would be the perfect place ask this question, because, unlike in natural forests, there are enough individuals of each species to be able to generalize about how they behave. The team compared between six and 13 individual trees in each of four nitrogen-fixing and three non-nitrogen fixing species to produce phosphatase.

More:
https://www.sciencedaily.com/releases/2018/08/180803121913.htm