Dissertation Research: The Effects of Soil Residence Time on Nitrogen Availability in Lowland Tropical Forests

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Ecologists seek to understand what controls the availability of nutrients in tropical forests, a globally important ecosystem type. While dogma suggests lowland tropical forests are rich in nitrogen, recent studies have observed large variation in tropical nitrogen dynamics across physical scales from small plots to the region. This project adds to dissertation research that has documented variation in soil nitrogen across a highly dissected tropical landscape in Costa Rica. Results suggest that differences in soil nitrogen are linked to patterns of erosion and soil development over the landscape. This project will test that by documenting the corresponding patterns in the physical and chemical development of soils across the same landscape. Chemical weathering of soils will be measured by comparing the amounts of minerals in the soils near the surface to those in underlying rocks. Soil residence times will be calculated by measuring the abundance of a rare atmospherically derived radionuclide, Beryllium-10. This information will be integrated with geomorphic, ecological and soil chemical data to explore the links between soil erosion, soil development and nitrogen availability.This project will increase the scope and value of a PhD dissertation, while shedding new light on the ecology of tropical forests, an under-studied biome of enormous socio-ecological importance. Collaborators in this project include Osa Conservation, a non-governmental organization that manages the study area on the Osa Peninsula of Costa Rica. University of Colorado undergraduate students will also be included in research trips to the Osa. The investigators will also collaborate with Osa Conservation to incorporate project results into educational materials.