Collaborative Research: Coupled Biogeochemistry and Geomorphology in Three Tropical Forest Ecosystems

生物地球化学中的一个主要范例是，由于岩石破裂提供的养分长期耗尽，古老的土壤是贫瘠的。营养物质的耗损，特别是磷的耗损，被认为在热带低地普遍存在，那里缺乏历史性的冰川作用，表明土壤比许多温带地区更古老。然而，这种假设几乎肯定是过于简单化了。热带景观是一个动态系统，在不同的地质和气候环境中，基岩向土壤的转化和通过侵蚀而产生的土壤流失以不同的速度发生。因此，绘制热带地区磷耗竭的程度需要解决一个基本的、很少被承认的问题，这是该项目的重点，磷在热带地区的停留时间是多长？它们是否足以使磷耗竭发生？这个问题将在一项多学科、多地点的研究中得到解决，该研究将首次将土壤肥力评估与有助于量化土壤停留时间的新技术结合起来。该项目将整合生物地球化学和地貌学，以回答有关土壤肥力和养分循环的基本问题，并将促进量化热带地区肥力差异的急需努力。它将支持几个机构的国际研究，并让每个地点的当地科学家和学生参与。除了培养研究生和博士后学者外，该项目还将为整合热带生态学、生物地球化学和地貌学的实地课程建立地点。

One of the dominant paradigms in biogeochemistry is that old soils are infertile as a result of the long term depletion of nutrients supplied through the breakdown of rocks. Nutrient depletion, particularly of phosphorus, is postulated to be widespread in tropical lowlands where the lack of historic glaciation suggests that soils are older than in many temperate regions. This assumption, however, is almost certainly an oversimplification. Tropical landscapes are dynamic systems in which the conversion of bedrock to soil and the removal of soil through erosion occur at different rates in different geologic and climatic settings. Thus mapping the extent of phosphorus depletion in the tropics requires addressing a fundamental and little acknowledged question that is the focus of this project, what are phosphorus residence times in the tropics and are they sufficient for phosphorus depletion to occur? This question will be addressed in a multidisciplinary, multisite study that will be the first to integrate assessments of soil fertility with new technologies that can help quantify soil residence times. This project will integrate biogeochemistry and geomorphology to answer fundamental questions about soil fertility and nutrient cycling and will promote a much needed effort to quantify differences in fertility in the tropics. It will support international research at several institutions and involve local scientists and students at each location. In addition to training graduate students and postdoctoral scholars, this project will establish site locations for a field course that integrates tropical ecology, biogeochemistry, and geomorphology.