9623969 Ewel Nutrient use efficiency in simplified tropical ecosystems. The efficiency with which plants use nutrients is a theme that unites physiological processes at many scales - from leaves, to plants, to whole ecosystems. Can differences in nutrient use efficiency at the leaf and plant level be scaled up to predict nutrient use efficiency at the ecosystem level? Nutrient use efficiency will be ilvestigated at different scales in a series of simplified tropical ecosystems: tree monocultures, and polycultures of trees and a very different life form - large, perennial monocots. Nutrient use efficiency will be calculated at the leaf level, as the maximum potential photosynthetic rate per unit nutrient content; at the plant level, as total biomass produced relative to nutrient uptake; and at the ecosystem level, as biomass production relative to nutrient supply. The study will provide an opportunity to compare nutrient use efficiency across scales, and across life forms. Understanding feedbacks between nutrient use efficiency at the leaf and plant level, and ecosystem nutrient use, will provide insight into the functional role of biodiversity. It will also provide a powerful tool in enabling restoration of degraded lands, and design of land use systems that are effective at nutrient conservation.
