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

生态学家试图了解是什么控制了热带森林中营养物质的可用性，这是一种全球重要的生态系统类型。虽然教条认为低地热带森林富含氮，但最近的研究观察到，从小块土地到整个地区，热带氮动态在物理尺度上存在很大差异。该项目增加了论文研究，记录了土壤氮在整个高度解剖的热带景观在哥斯达黎加的变化。结果表明，土壤氮的差异与景观的侵蚀和土壤发育模式有关。该项目将通过记录同一景观中土壤物理和化学发展的相应模式来测试这一点。土壤的化学风化将通过比较表层土壤中的矿物质含量与下层岩石中的矿物质含量来测量。土壤停留时间将通过测量一种稀有的大气衍生放射性核素Berken-10的丰度来计算。这些信息将与地貌、生态和土壤化学数据相结合，以探索土壤侵蚀、土壤发育和氮供应之间的联系。该项目将增加博士论文的范围和价值，同时为热带森林的生态学提供新的视角，热带森林是一个研究不足的生物群落，具有巨大的社会生态重要性。该项目的合作者包括Osa Conservation，这是一个管理哥斯达黎加Osa半岛研究区的非政府组织。科罗拉多大学的本科生也将参加到奥萨的研究旅行。 调查人员还将与Osa Conservation合作，将项目结果纳入教育材料。

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.