P2C2:Collaborative Research: Rocky Mountain Ecohydrology During the Eemian Interglacial

该奖项的目标是评估伊米米亚间冰期（开始于约13万年前，结束于约11.5万年前）对落基山森林健康的控制，这是地球上最近的一个时期。在美国历史上，生长季节的温度超过了今天的温度。由于emian变暖发生在工业化前部分二氧化碳（pCO2）浓度的背景下，该研究旨在分离优势树种对生长季节温度的反应，这些温度与预计到公元2100年的正常温度相当。通过与丹佛自然与科学博物馆的合作，该项目利用了最近从科罗拉多州斯诺马斯恢复并保存完好的埃米米亚时代的木材样本。Eemian木材样本提供了一个难得的机会，可以探索美国西部森林过去对夏季温度（比今天高3-5°C）的反应。北方森林在全球碳循环中发挥着关键作用，并提供重要的大型动物栖息地和生态系统服务。预计下个世纪将发生的变暖、山地水文变化（如融雪时间）和二氧化碳分压升高的同时和耦合影响，导致对该生态系统对全球变化的响应产生了截然不同的预测。研究人员将对来自落基山脉南部的现代和伊米恩木材样本进行亚季节分解的氧-18和碳-13 （d18O和d13C）同位素测量，这些木材样本在伊米恩时期很常见，至今仍占主导地位。这些木材样本将用于测试生长季节长度、水分利用（即夏季降雨与融雪）和Eemian期间（即温暖的温度和低二氧化碳分压）与今天（即“凉爽”的温度和高二氧化碳分压）的水利用效率。这一分析将提供一个清晰的问题，即工厂最近的变化是否？水分利用效率是CO2施肥效应或CO2与温度耦合变化的产物。除了同位素测量之外，研究人员还将在Eemian和现代强迫下生成嵌套（50公里分辨率）同位素支持的环流模型（GCM）模拟，为用于解释代理数据的生态水文和生态生理过程模型提供气候输入。这项研究的成果将评估温度驱动的地表水文（雪和土壤过程）、大气环流（北美季风的范围和持续时间）和地表/叶片温度的变化如何共同改善或破坏森林健康，包括美国西部大型野火和树木死亡率的增加。该项目将支持两名从事古气候学、生态学、生态学和生态学交叉研究的早期职业科学家。还有气候动力学。以芝加哥为基地的多机构合作将促进本科生和研究生在稳定同位素地球化学和气候模型方面的研究机会，这些研究在机构之间得到利用，是21世纪科学培训的基础。此外，与丹佛自然与科学博物馆在研究和教育方面有着强有力的合作。

This award's goal is to assess controls on Rocky Mountain forest health during the Eemian-interglacial (beginning ~130,000 and ending ~ 115,000 years ago), the most recent period in Earth?s history when growing season temperatures exceeded those of today. Since the Eemian warming occurred in the context of pre-industrial partial carbon dioxide (pCO2) concentrations, the research aims to isolate the response of dominant tree species to growing season temperatures that are comparable to those predicted to be normal by AD 2100. The project takes advantage of recently recovered and well-preserved Eemian-age wood samples from Snowmass, Colorado available to this project through collaboration with the Denver Museum of Nature and Science. The Eemian wood samples provide a rare opportunity to explore how forests in the western U.S. have responded in the past to summer temperatures ~3-5°C higher than today?s. Boreal forests play a critical role in the global carbon cycle and provide important macrofaunal habitat and ecosystem services. The simultaneous and coupled influences of warming, changes in mountain hydrology (such as the timing of snowmelt) and elevated pCO2 that are predicted to occur over the next century have led to widely disparate projections on the response of this ecosystem to global change. The researchers will make sub-seasonally-resolved delta oxygen-18 and carbon-13 (d18O and d13C) isotopic measurements on modern and Eemian wood samples from species in the southern Rocky Mountains that were common during the Eemian and remain dominant today. These wood samples will be used to test how growing season length, water utilization (i.e., summer rain versus snowmelt) and Water Use Efficiency during the Eemian (i.e., warm temperatures and low pCO2) compare to today (i.e., "cool" temperatures and high pCO2). This analysis will provide clarity on whether recent changes in a plant?s Water Use Efficiency is a product of the CO2 fertilization effect or from coupled changes in CO2 and temperature. In addition to the isotope measurements, the researchers will generate nested (50 km resolution) isotope-enabled general circulation model (GCM) simulations under Eemian and modern forcings to provide climatic inputs for the ecohydrological and ecophysiological process models used to interpret the proxy data. The products of this research will be an assessment of how temperature-driven shifts in surface hydrology (snow and soil processes), atmospheric circulation (North American Monsoon extent and duration), and surface/leaf temperatures combine to improve or disintegrate forest health, including increases in large wildfires and rates of tree mortality in the western U.S.The project will support two early career scientists working at the intersection of paleoclimatology, ecology, and climate dynamics. The Chicago-based multi-institutional collaboration will facilitate undergraduate and graduate research opportunities in stable isotope geochemistry and climate modeling that are leveraged between institutions and are fundamental for twenty-first century scientific training. Additionally, there is a strong collaboration with the Denver Museum of Nature and Science for research and education.