BE/CBC: Complex Interactions Among Water, Nutrients and Carbon Stocks and Fluxes Across a Natural Fertility Gradient in Tropical Rain Forest

[421178]奥伯鲍尔世界上的热带雨林在全球碳预算中扮演着不成比例的重要角色。它们目前和未来的碳平衡尚不清楚，并且由于我们对该生物群系中碳循环的理解存在很大差距，因此仍然存在争议。迄今为止，对这些森林的相关研究在很大程度上仅限于短时间内的少量碳通量。目前还没有对热带雨林进行过多年的综合研究，研究地上和地下碳循环的多个组成部分，以及它们如何与水、养分和气候因素相互作用并受其控制。这个生物复杂性项目将填补这些知识空白，将对热带森林碳循环的了解提升到一个新的水平。我们将在一个研究非常充分的热带雨林（哥斯达黎加的La Selva）进行的补充研究的基础上，首次对森林碳、养分和水文循环进行综合研究。我们的研究将对比ENSO循环不同阶段的影响，并将比较大范围土壤肥力水平的林分，从而代表世界上许多热带森林的肥力水平。我们的团队拥有广泛的专业知识——热带森林生态学、植物生态生理学、微气象学、森林生物地球化学、森林水文学、生态系统建模、遥感、无脊椎动物生物学——这将使我们能够共同解决森林中碳、营养和水循环的许多相互作用方面的问题。有了La Selva正在进行的研究的补充数据，该项目将提供比任何基金会所获得的更全面的森林碳预算分析。由于我们的研究将持续近三年，并且对于一些建立在长期测量基础上的数据集，我们将能够研究气候因素（如温度和降雨）的年际变化如何影响这种生态系统类型中碳、营养物质和水之间复杂的相互作用和反馈。通过研究所有这些周期，随着时间的推移，并跨越土壤肥力水平的强大梯度，我们将能够识别和量化所有这些共变过程中的复杂约束和反馈。我们将通过从我们的数据开发一个基于经验的热带雨林版本的生态系统过程模型CENTURY来整合我们的发现。我们将使用这个模型来发展一个概括的、预测性的理解，了解TRF目前如何处理碳，以及TRF碳平衡可能对持续的气候变化做出反应。更广泛的影响-通过多方面的教育计划，该项目将向不同层次的学生、决策者和公众传达我们的研究成果和生物复杂性、全球变化和生态系统科学的概念。该项目的研究部分将为博士后研究员、研究生、众多本科生助理以及哥斯达黎加研究生和助理提供出色的机会，通过亲身参与热带地区的跨学科科学，进行强化研究培训。该项目将以讲座、野外问题/漫步和非正式互动的形式呈现给每年访问实地的数千名大学水平野外生物学课程的本科生和研究生。我们与仙童热带植物园（Fairchild Tropical Botanic Garden）和热带研究组织（Organization for Tropical Studies）合作，开展推广项目，每年将惠及美国和哥斯达黎加的数千名儿童、学生和公众。项目目标的公共教育部分将提高学生、教师和公众对热带地区水、碳和营养过程的连通性的认识，以及它们的影响如何扩展到全球范围。

0421178OberbauerThe world's tropical rain forests play a disproportionately large role in the global carbon budget. Their current and future carbon balance is poorly understood and remains controversial because of large gaps in our understanding of carbon cycling in this biome. To date relevant studies in these forests have largely been limited to few carbon fluxes that were followed for short periods. For no topical rain forest has there been a multi-year integrated study of multiple components of both aboveground and belowground carbon cycling and how they interact with and are controlled by water, nutrients, and climatic factors. This Biocomplexity project will address these knowledge gaps to bring understand of tropical forest carbon cycling to a new level.We will build on complementary on-going research in an exceptionally well-studied tropical rain forest (La Selva, Costa Rica) for a first-time integrated study of forest carbon, nutrient, and hydrological cycles. Our study will contrast the effects of different phases of the ENSO cycle and will compare stands across a broad range of soil fertility levels, thus representative of the fertility levels of many of the world's tropical forests. The broad range of expertise represented in our team - tropical forest ecology, plant ecophysiology, micrometeorology, forest biogeochemistry, forest hydrology, ecosystem modeling, remote sensing, invertebrate biology - will allow us to together address many interacting aspects of the carbon, nutrient, and water cycles in this forest. With complementary data from on-going studies at La Selva, this project will provide a more comprehensive analysis of the forest carbon budget than has been attained for any TRF. Because our studies will be continuous through almost three years and for some data sets build on long-term measurements, we will be able to study how inter-year variation in climatic factors such as temperature and rainfall affect the complex interactions and feedbacks among carbon, nutrients, and water in this ecosystem type. By studying all of these cycles in concert, through time, and across a strong gradient of soil fertility levels, we will be able to identify and quantify the complex constraints and feedbacks among all these co-varying processes. We will integrate our findings by developing from our data an empirically-based tropical rain forest version of the ecosystem process model CENTURY. We will use this model to develop a generalizable, predictive understanding of how TRF currently processes carbon, and TRF carbon balance is likely to respond to the on-going changes in climate.Broader impacts - Through a many-faceted education program, this project will convey both our research findings and the concepts of Biocomplexity, global change, and ecosystem science, to diverse levels of students decision-makers, and the general public. The research component of this project will provide outstanding opportunities for intensive research training by hands-on participation in interdisciplinary science in the tropics for a postdoctoral fellow, graduate students, numerous undergraduate assistants, and Costa Rican postgraduates and assistants. The project will be presented in the form of lectures, field problems/walks, and informal interactions to the thousands of undergraduate and graduate students in university-level field biology courses that visit the field site annually. We have partnered with Fairchild Tropical Botanic Garden and the Organization for Tropical Studies with outreach programs that will annually reach thousands of children, students and the general public, both in the U.S. and in Costa Rica. Public education components of the project target will raise awareness of the school children, their teachers, and the general public to the connectivity of water, carbon and nutrient processes in the tropics and how their effects can extend to the global scale.