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

该奖项的目标是评估伊米亚-间冰期(从13万年前开始到11.5万年前结束)对落基山脉森林健康的控制，这是地球上S历史上生长季节温度超过今天的最近时期。由于Eemian变暖发生在工业化前部分二氧化碳(PCO2)浓度的背景下，这项研究的目的是分离出优势树种对生长季温度的反应，这些温度与公元2100年预测的正常温度相当。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伊米亚时代木材样本，通过与丹佛自然与科学博物馆的合作，可用于该项目。伊米亚森林样本提供了一个难得的机会来探索美国西部的森林在过去如何应对比现在高3-5摄氏度的夏季温度？S。北方森林在全球碳循环中扮演着关键角色，并提供重要的大型动物栖息地和生态系统服务。气候变暖、山脉水文变化(如融雪的时间)和二氧化碳浓度升高的同时和共同影响，预计将在下个世纪发生，导致对该生态系统对全球变化的反应的预测大相径庭。研究人员将对落基山脉南部物种的现代和埃米亚木材样本进行亚季节分辨的氧-18和碳13(d18O和d13C)同位素测量，这些物种在埃米安时期很常见，至今仍占主导地位。这些木材样本将被用来测试Eemian期间的生长季长度、水分利用(即夏季降雨与融雪)和水分利用效率(即温暖的温度和低二氧化碳含量)与今天(即“凉爽”的温度和高二氧化碳含量)相比有何不同。这一分析将澄清植物最近的变化？S水分利用效率是二氧化碳施肥效应的产物，还是二氧化碳和温度耦合变化的产物。除了同位素测量，研究人员还将在Eemian和现代强迫下生成嵌套的(50公里分辨率)同位素启用的大气环流模式(GCM)模拟，为用于解释替代数据的生态水文和生态生理过程模型提供气候输入。这项研究的成果将是对地表水文学(雪和土壤过程)、大气环流(北美季风的范围和持续时间)以及地表/树叶温度如何结合起来改善或破坏森林健康的评估，包括美国西部大型野火和树木死亡率的增加。该项目将支持两名在古气候学、生态学和气候动力学交叉领域工作的早期职业科学家。总部设在芝加哥的多机构合作将促进在稳定同位素地球化学和气候模拟方面的本科生和研究生研究机会，这些研究机会是机构之间的杠杆作用，是21世纪科学培训的基础。此外，还与丹佛自然与科学博物馆在研究和教育方面进行了强有力的合作。

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.