Examining differential drought responses of forest trees with phylogenies and process-based catchment water age modeling

森林生态系统为人类社会和自然环境提供了许多好处，如减轻洪水，固碳和支持生物多样性的栖息地。然而，由于气候变化的影响，包括森林景观中干旱发生频率和强度的增加，森林提供的惠益受到威胁。温带、干旱和热带森林对干旱的适应能力在全球范围内正在下降;这种下降的原因尚不清楚。 一个困难是，用于研究森林生态系统变化的计算机模型要求研究人员准确估计植物的吸水策略。然而，由于缺乏现成的数据集，特别是在世界上缺乏数据的地区，实现这一目标所需的模型信息面临挑战。在这个项目中，研究人员将研究通过使用树木的进化历史来估计性状值来改善生态系统模型中植物代表性的方法。然后，该项目将使用这些改进的模型来检验森林复原力的变化与降水和植物根系吸水之间的时间变化有关的假设。这项研究将为旨在促进森林抗旱能力的管理实践提供信息，它将推进生态系统建模，并建立科学工作者的能力。这项研究将把土壤和植被木质部中示踪剂水龄跟踪，植物水力学的生态水文模拟和系统发育数据分析的最新发展联系起来，这三个关键领域是回答连接水文学和生态系统科学的关键问题所必需的。研究人员将开发一种方法，通过系统发育特征估计（PTE）在水文和生态系统模型中参数化植被水力特征，支持数据匮乏地区的森林模拟。PTE将被纳入基于过程的生态水文和陆地表面模型。然后，研究人员将利用代表不同气候、地质和树种组成的丰富水文和水同位素数据集，对12个研究集水区的建模方法进行验证。由此产生的基于过程的模型将用于研究气候变化对集水年龄、森林初级生产力和蒸腾作用、树木水力策略、及其对干旱风险和森林恢复力的综合影响。该奖项由水文科学和环境生物学部共同资助，生态系统科学集群计划。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Forested ecosystems provide many benefits to human society and the natural environment, such as alleviating floods, sequestering carbon, and supporting habitats for biodiversity. However, the benefits that forests provide are at risk due to the effects of climate change, including higher frequency and greater intensity of drought in forested landscapes. The resilience of temperate, arid, and tropical forests to drought is declining globally; and the reasons for this decline are not clear. One difficulty is that computer models that are used to study changes in forested ecosystems require researchers to accurately estimate the water uptake strategies of plants. However, the information needed for models, to accomplish this goal, are challenged because of the lack of readily available datasets, particularly in data-poor regions of the world. For this project, researchers will investigate methods to improve the representation of plants in ecosystem models by using the evolutionary histories of trees to estimate trait values. The project will then use these improved models to test the hypothesis that changes in forest resilience are related to changes in the elapsed time between precipitation and water uptake by plant roots. This research will inform management practices designed to promote drought resilience in forests, it will advance ecosystem modeling, and build capacity in the scientific workforce.This research will link recent developments from tracer derived water age tracking in soils and vegetation xylem, ecohydrological simulation of plant hydraulics, and phylogenetic data analytics, which are three key areas that are necessary to answer critical questions that bridge hydrology and ecosystems science. The investigators will develop an approach to parameterize vegetation hydraulic traits in hydrologic and ecosystem models through phylogenetic trait estimation (PTE), supporting forest simulations in data-poor regions. The PTE will be integrated into process-based ecohydrological and land surface models. The researchers will then validate this modeling approach for twelve research catchments with rich hydrologic and water isotopic datasets representing diverse climates, geologies, and tree species compositions. The resulting process-based models will be applied to study the combined and interrelated effects of climate change on catchment water ages, forest primary production and transpiration, tree hydraulic strategies, and their composite effect on drought risk and forest resilience.This award is co-funded by the Hydrologic Sciences and the Division of Environmental Biology – Ecosystem Sciences Cluster programs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.