Pine trees and shrubs, struggling to survive in the extremely infertilesoils of Northern California's coastal Pygmy Forest, alter their soil environment to monopolize and conserve limited soil nutrients,according to UC Davis researchers. In their needles and leaves, the pines and shrubs produce high levels of chemicals called polyphenols. These chemicals bind up organic forms of nitrogen in the decomposing leaf litter, preventing the vital nutrient from washing out of the soil. By this process, the pines and shrubs are able to reclaim the nitrogen via the symbiotic fungi associated with their roots. The fungi essentially "feed" the nitrogen back to the shrubs and trees. "Ecologists have long thought that plants produce high levels of polyphenols as chemical defenses against plant-eating animals and insects," says biogeochemist Robert Northup. "Our research, however, suggests that the polyphenols' role is in preventing organic nitrogen from being converted into forms that would be lost through leaching or to competing organisms." The findings should help foresters and agronomists protect and rehabilitate nutrient-depleted soils, say Northup and his colleague, associate professor Randy Dahlgren. They presented their findings in last week's issue of the weekly journal Nature.