Interactions between Rainfall, Nutrient Cycles and Decomposition in Lowland Tropical Rainforests

热带雨林与大气交换的二氧化碳和水比任何其他陆地生物群系都多，因此在气候调节中发挥着重要作用。热带生物群落的湿润部分在树木生物量和土壤中储存了大量的碳，但是这些储量——尤其是土壤碳——可能对预测的降雨变化很敏感。因此，该项目将控制哥斯达黎加潮湿雨林中到达土壤的降雨量，并测试这种变化如何改变落叶和土壤碳分解，以及从土壤表面释放到大气中的二氧化碳量。此外，它还将测试氮和磷的有效性如何影响对降雨操纵的反应，氮和磷是热带生物群系中差异很大的关键营养物质。作为一个整体，这些实验将展示潮湿热带森林的降雨变化如何影响与地球气候直接相关的生态系统过程，重点是土壤碳储存。这里产生的数据将提高对这个巨大的土壤碳库如何对气候变化做出反应的理解，从而了解它如何缓和或增强持续的气候变化。最后，该项目将为美国和哥斯达黎加的年轻科学家提供培训和教育，并将为科罗拉多州的学童制定一个推广计划。

Tropical rain forests exchange more carbon dioxide and water with the atmosphere than any other terrestrial biome, and thus play a major role in climate regulation. Wetter portions of the tropical biome store large amounts of carbon in tree biomass and soils, but those reserves - especially soil carbon - may be sensitive to predicted changes in rainfall. Thus, this project will manipulate the amount of rainfall that reaches soils in a wet Costa Rican rainforest, and test how such changes alter leaf litter and soil carbon decomposition, and the amount of CO2 that is released from the soil surface to the atmosphere. In addition, it will test how nitrogen and phosphorus availability, key nutrients that also vary greatly across the tropical biome, affect the responses to rainfall manipulation. Taken as a whole, the experiments will demonstrate how changes in rainfall in wet tropical forests may affect ecosystem processes that have direct relevance to earth's climate, with a focus on soil carbon storage. The data produced here will improve understanding of how this large soil carbon reservoir may respond to a changing climate, and thus how it might moderate or augment continued climate change. Finally, the project will provide training and education to young scientists in the U.S. and Costa Rica, and will develop an outreach program for Colorado school children.