Some Trees Farm Bacteria to Help Supply Nutrients
By Robert J. Korpella
First posted on 07-29-2010
Scientists have discovered that certain types of trees, like beech and oak, that grow in nutrient-poor forest soil, cultivate certain root microbes that create the food compounds the trees need to survive.
“In acidic forest soils, availability of inorganic nutrients is a tree-growth-limiting factor,” Stéphane Uroz, one of the researchers, explains. “These microbes are exceptionally efficient at turning inorganic minerals into nutrients that the trees can use. “
The process of breaking down inorganic minerals into nutrients is referred to as mineral weathering. Bacteria that have the capability of mineral weathering can release vital nutrients like iron from the soil. Trees that have adapted to cultivate these bacteria have a distinct advantage over other trees.
During the study, researchers took soil samples from the root areas of beech, oak and spruce trees, then cultured the samples to understand their bacterial make up. Oak and beech root samples were rich with mineral-weathering bacteria compared to the surrounding soil. This was not the case with spruce samples.
“Our results suggest that certain tree species have developed indirect strategies for mineral weathering in nutrient-poor soils, which lie in the selection of bacterial communities with efficient mineral weathering potentials” says Uroz.