Human activities such as the combustion of fossil fuels and the application of chemical fertilizers have more than doubled the quantity of nitrogen in terrestrial ecosystems. This increase can have profound consequences for ecosystem properties, but how it influences the dynamics of plant populations remains unknown. Bruna and his collaborators will conduct an experimental test of how nitrogen enhancement influences the dynamics of plant populations in tropical savannas. They will manipulate nitrogen levels in experimental plots and use matrix models to elucidate the demography of a dominant bunchgrass (Tristachya leiostachya), and to observe how changes in the abundance of this species influence ecosystem properties such rates of net nitrogen mineralization.
Because the ecological responses of tropical ecosystems to nitrogen deposition are likely to be dramatically different from those of temperate ones, Bruna's research will address a major gap in our understanding of how tropical plant populations are regulated. Furthermore, anthropogenic nitrogen deposition is widely recognized as an emerging threat to ecosystems throughout the developing world. Thus, this work will have important implications for conservation. Finally, this research will support the academic advancement of minority scientists, as well as enhance the ecological content of courses taught by faculty at community colleges and minority-serving institutions.
