Collaborative Research: Fern Biogeochemistry and Ecosystem Stoichiometry

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Ferns are abundant components of many ecosystems, and they differ substantially in chemistry from the plants with which they occur. These contrasts are particularly strong in the climbing ferns and tree ferns; these ancient lineages contain remarkably low concentrations of Ca and may support a different set of organic compounds. Many Hawaiian rainforests are co-dominated by a tree and a basal fern, and the fern in these systems can contribute 50% of aboveground net primary production and N and P cycling. The proposed research will apply a combination of observations, experiments, and modeling to understand the dynamics of Ca and other elements, and of recalcitrant organic compounds, in these relatively simple systems. Single-cell x-ray microanalysis will be used to determine differences in chemistry between trees and ferns on the one hand, and fungi and bacteria on the other, and organic compounds will be analyzed via pyrolysis GC-MS and synchrotron FTIR, along the decay continuum from litter to soil organic matter. This proposed research will integrate information and approaches from phylogeny, biochemistry, ecology, and organic geochemistry to determine how differences between ferns and trees affect the decomposer community and the decomposition process. The understanding of fundamental processes gained in this model system will broaden our understanding of terrestrial ecosystems. It will also link education to basic research by incorporating students at levels from high school to Ph.D. into the research. Some of these students will be Native Hawaiians, through our interactions with Kamehameha Schools and the University of Hawaii - Hilo Hawaiian Internship Program. In addition, the research will build scientific capacity by applying several modern analytical techniques to ecological questions.