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

在过去的一个世纪里，大气中二氧化碳的增加是有据可查的，然而，这种变化的长期后果还没有得到很好的理解。二氧化碳浓度的实验操作已经研究了个体、种群和生态系统水平的响应，然而这些实验在规模和持续时间上都是有限的。为了了解未来几十年生态过程和反馈的变化将如何推动生态系统的变化，需要对大气中二氧化碳浓度升高的生态响应进行长期研究。该项目将测试黄石国家公园内两个森林地点作为长期二氧化碳富集地点的适用性。最初的测量显示，在地热资源下坡的地方，大气中的二氧化碳含量升高。这些地点距离污染源1-2公里，没有显示出地热改变土壤的证据。将对树核进行分析，以测试这些地点暴露在高浓度二氧化碳中的时间；对土壤进行阳离子分析，并与潜在的对照地点进行比较；在整个生长季节收集气体样本，以测试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）的存在，这些气体可能会混淆这些地点与相邻对照地点的比较。该项目的智力价值在于，它有可能证明这些地点可以作为现有二氧化碳富集实验的长期（50 - 100年）类似物，提供比现在可能的更遥远的未来视角。如果这个项目成功地证明了这些地点的适宜性，其主要的广泛影响将是确定一种可能被科学家利用的资源，这些科学家对大气二氧化碳增加对陆地生态系统许多方面的长期影响感兴趣。

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.