SGER: High Carbon Dioxide Habitats of Yellowstone as a Long-Term Complement to Face Studies

过去一个世纪大气中二氧化碳的增加是有据可查的，但这种变化的长期后果并没有得到很好的理解。对二氧化碳浓度的实验操作研究了个体、种群和生态系统水平的反应，但这些实验在规模和持续时间上都是有限的。需要对大气二氧化碳浓度升高的生态反应进行长期研究，以了解生态过程和反馈的变化将如何在未来几十年推动生态系统的变化。该项目将测试黄石国家公园的两个森林地点是否适合用作长期的二氧化碳浓缩场。初步测量显示，地热源导致下坡地点的大气二氧化碳含量上升。遗址距离污染源1-2公里，没有证据表明有地热改变的土壤。将对树心进行分析，以测试这些地点暴露在高二氧化碳中的时间有多长，将分析土壤中的阳离子并将其与潜在的对照地点进行比较，并将在整个生长季节收集气体样本，以测试是否存在二氧化碳以外的气体(例如，硫化氢、氨、甲烷，通常与地热活动有关的气体)，这些气体可能会混淆这些地点与邻近对照地点的比较。该项目的学术价值在于，它有可能证明这些地点可以作为现有二氧化碳浓缩实验的长期(50-100年)类比，提供比现在可能的更远的未来视角。如果该项目成功地证明了这些地点的适宜性，其主要的更广泛的影响将是确定一种可能被科学家使用的资源，这些科学家对大气二氧化碳增加对陆地生态系统的许多方面的长期后果感兴趣。

The increase in atmospheric carbon dioxide that has occurred over the past century is well documented, however the long term consequences of this change are not well understood. Experimental manipulations of CO2 concentration have examined individual, population, and ecosystem level responses, however these experiments are limited in size and duration. Long term studies of ecological responses to elevated atmospheric CO2 are needed to understand how changes in ecological processes and feedbacks will drive ecosystem change in the coming decades. This project will test the suitability of two forested sites in Yellowstone National Park for use as long term CO2 enrichment sites. Initial measurements revealed elevated atmospheric CO2 at sites downhill from geothermal sources. Sites are 1-2 km away from the sources, and show no evidence of geothermally altered soils. Tree cores will be analyzed to test how long these sites have been exposed to elevated CO2, soils will be analyzed for cations and compared to potential control sites, and gas samples will be collected throughout the growing season to test for the presence of gases other than CO2 (e.g., hydrogen sulfide, ammonia, methane, gases commonly associated with geothermal activity) that could confound comparison of these sites with adjacent control sites. The intellectual merit of this project is that it has the potential to demonstrate that these sites can serve as long term (50 - 100 year) analogs of existing CO2 enrichment experiments, providing a view much farther into the future than is now possible. The primary broader impact of this project, if it successfully demonstrates the suitability of these sites, will be the identification of a resource that is likely to be used by scientists who are interested in long term consequences of increased atmospheric CO2 on many aspects of terrestrial ecosystems.