Mathematical Modelling of Climate Change Impacts on Terrestrial Ecosystems

我的研究致力于开发和测试各种自然和管理的陆地生态系统的综合模型（生态系统）。模型假设尽可能从控制生态系统行为的物理、化学和生物学的基本理论出发。因此，模型参数化在很大程度上独立于模型开发，从而避免了作为模型制定工件的算法和参数。因此，它能够针对这里建议的详细过程级观察进行良好约束的测试。这些模式可对研究气候变化的影响作出宝贵贡献，特别是对北极地区的影响，预计下个世纪北极地区的变暖速度将是全球平均速度的两倍。这些影响正在美国能源部的北极下一代生态系统实验（NGEE）中进行研究，该实验的一个关键目标是“通过提供一个过程丰富的生态系统模型来推进对地球气候和环境系统的强有力的预测性理解……在这个模型中，北极生态系统在不断变化的气候中的演变可以建模”。我建议通过参与NGEE arctic，利用ecosys解决NGEE所基于的五个科学问题，进一步发展我们模拟气候变化对不同北极生态系统影响的能力：****(1)在气候变化中，景观的结构和组织如何控制碳和营养物质的储存和通量？****(2)在一系列永久冻土条件下，什么将控制CO2和CH4通量的速率？****(3)气候变暖和永久冻土融化将如何影响地上和地下植物的功能性状，以及对北极生态系统碳、水和养分通量的影响？****(4)是什么控制了目前北极灌木的分布？在21世纪，灌木的分布和相关的气候反馈将如何随着预期的变暖而变化？****(5)北极在何时、何地以及为何会变得更湿润或更干燥，对气候强迫的影响是什么？*******对于每个问题，我都在ecosys中开发了模型假设，并使用在NGEE Arctic获得的数据进行了测试协议。这些方案将在地块、景观和区域尺度上进行，使用不同的热、水文和生物动力学实验观测（土壤温度、水和冰含量、活动层深度、生态系统生产力、能源和温室气体交换、微生物和植物功能类型）。与以前的北极模拟研究相比，这些假设的制定和测试过程水平更加详细和全面，并将大大提高我们对气候变化对北极生态系统影响的预测的信心。*Ecosys将通过与劳伦斯伯克利国家实验室正在进行的美国能源部社区地球系统模型CESM的耦合，为这些预测做出直接贡献。**

My research is dedicated to developing and testing a comprehensive model (ecosys) of diverse natural and managed terrestrial ecosystems. Model hypotheses are formulated as much as possible from basic theory in physics, chemistry and biology by which ecosystem behaviour is governed. Consequently model parameterization is largely independent of model development, thereby avoiding algorithms and parameters that are artifacts of model formulation. It is therefore capable of well-constrained tests against detailed process-level observations as proposed here.***Such models can make a valuable contribution to the study of climate change impacts, particularly those in the arctic which is projected to warm at a rate twice that of the global average in the next century. These impacts are being studied in the US DoE's Next Generation Ecosystem Experiment (NGEE) Arctic, a key objective of which is ‘to advance a robust predictive understanding of Earth's climate and environmental systems by delivering a process-rich ecosystem model … in which the evolution of Arctic ecosystems in a changing climate can be modeled'. I propose to further develop our capability to model climate change impacts on diverse arctic ecosystems through participation in NGEE Arctic by using ecosys to address the five scientific questions upon which NGEE is based:****(1) How does the structure and organization of the landscape control the storage and flux of carbon and nutrients in a changing climate?****(2) What will control rates of CO2 and CH4 fluxes across a range of permafrost conditions?****(3) How will warming and permafrost thaw affect above- and belowground plant functional traits, and what are the consequences for Arctic ecosystem carbon, water, and nutrient fluxes?****(4) What controls the current distribution of Arctic shrubs, and how will shrub distributions and associated climate feedbacks shift with expected warming in the 21st century?****(5) Where, when, and why will the Arctic become wetter or drier, and what are the implications for climate forcing?*******For each question, I have developed model hypotheses in ecosys and testing protocols with data acquired in NGEE Arctic. These protocols will be conducted at plot, landscape and regional scales using diverse experimental observations of thermal, hydrological and biological dynamics (soil temperature, water and ice content, active layer depths, ecosystem productivity, energy and greenhouse gas exchange, microbial and plant functional types). The process levels at which these hypotheses are formulated and tested are more detailed and comprehensive than those of previous arctic modelling studies, and will greatly improve confidence in our projections of climate change impacts on arctic ecosystems.*Ecosys will make direct contributions to these projections through its coupling with the USDoE's Community Earth System Model CESM currently underway at the Lawrence Berkeley National Lab.**