Understanding the effects of above- and belowground linkages on carbon cycling in a high latitude, coastal wetland

阿拉斯加西部的育空-库斯科维姆三角洲是世界上最大的河流三角洲之一，也是数百万候鸟的夏季家园。尽管食性鸟类强烈影响着河流三角洲的植物群落，但人们对北极水禽种群的变化如何影响土壤中二氧化碳和甲烷等温室气体的释放知之甚少。该项目正在研究育空-库斯科维姆三角洲的放牧鸟类、植物群落、土壤微生物和生态系统碳循环之间的关系，以预测这些生态系统未来可能发生的变化。该项目将制作关于鹅、植物、微生物和温室气体之间关系的在线学习模块，并将其传播给当地阿拉斯加学区的中学生。当地学生还将接受有关研究的培训，并制作有关研究的当地广播故事。最后，这项研究将通过在线媒体和地方电视频道播出。该项目结合野外实验、实验室实验和生物地球化学模型，从机理上了解放牧对高纬度沿海湿地温室气体动态的影响。该项目通过一项为期两年的田间实验，量化了鹅的放牧、践踏和粪便沉积对微生物群落、土壤小气候和碳动态的独立和综合影响。一项实验室实验正在被用来量化草食动物对土壤碳输入数量和质量的影响如何影响微生物群落结构和碳动态。最后，这些实验的结果被用来对生物地球化学模拟模型进行参数化，以预测在未来气候下，草食动物的变化将如何影响亚北极潮湿莎草的碳动态。通过用这种整体观点检验草食的影响，生态系统模型的预测能力将增加，特别是对于草食是初级生产和植物群落组成的普遍驱动因素的高纬度系统。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Yukon-Kuskokwim Delta of western Alaska is one of the largest river deltas in the world and the summer home to millions of migratory birds. Although grazing birds strongly affect the plant communities in river deltas, little is known about how changing waterfowl populations in the Arctic affect the release from soils of greenhouse gases like carbon dioxide and methane. This project is examining relationships among grazing birds, plant communities, soil microbes, and ecosystem carbon cycling in the Yukon-Kuskokwim Delta to predict how these ecosystems may change in the future. This project will produce on-line learning modules about the relationships among geese, plants, microbes, and greenhouse gases and disseminate them to middle school students in the local Alaskan school district. Local students will also be trained in and produce local radio stories about the research. Finally, the research will be broadcasted through on-line media outlets and local TV channels. This project is using a combination of field experiments, lab experiments, and biogeochemical models to provide a mechanistic understanding of the effects of grazing on greenhouse gas dynamics in a high latitude coastal wetland. This project is quantifying the independent and combined effects of grazing, trampling, and feces deposition by geese on microbial communities, soil microclimate, and carbon dynamics using a two-year field experiment. A laboratory experiment is being used to quantify how herbivore-mediated changes in the quantity and quality of soil carbon inputs affect microbial community structure and carbon dynamics. Finally, results from these experiments are being used to parameterize a biogeochemical simulation model to predict how changes in herbivory will affect carbon dynamics in subarctic wet sedge under future climates. By examining the effects of herbivory with this holistic view, the predictive power of ecosystem models will be increased, especially for high-latitude systems where herbivory is a prevalent driver of primary production and plant community composition.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.