DISSERTATION RESEARCH: Exploring the Impacts of Long-Term Warming on Arctic Soils: Linking Microbial Communities with Seasonal Biogeochemical Dynamics.

据估计，北方永久冻土区土壤有机碳（SOC）总量是大气中C的两倍多。这种SOC的积累是由寒冷的气候限制分解驱动的。气候模型预测，北极将在未来世纪变暖，因此微生物加速SOC分解是陆地生态系统向大气释放温室气体的最重要的潜在反馈之一。冬季积雪和春季解冻对分解的影响尤为重要。 然而，很少有研究探讨长期变暖将如何影响土壤生物地球化学动态的季节性。为了解决这一知识差距，该研究项目使用了1988年在图里克，AK长期生态研究基地启动的温室实验，通过跨季节和土壤层的重复采样，探索长期变暖对北极土壤微生物动力学和养分循环的影响。细菌和真菌群落？将对DNA进行研究，以从遗传学上描述不同生物体如何对跨季节和土壤层的长期变暖作出反应。这项工作正在被用来开发和参数化冻土带土壤的机械模型？更广泛的影响：从中产生的数据和模型是北极系统科学计划支持的多机构合作努力的一部分。改变北极系统的季节性倡议。该模型将北极微生物群落的结构和活动与碳和营养循环直接联系起来，提高了我们预测该系统中的地球化学循环将如何应对快速气候变暖的能力。此外，通过该项目生成的任何焦磷酸测序衍生序列将被添加到NIH GenBank数据库中。除了科学合作外，该项目还将促进几名学生在地球化学科学方面的发展，其中包括两名女本科生和一名少数民族高中生，并支持他们参与针对当地K-12社区的几个科学推广项目。NSF DDIG赠款将促进女科学家完成博士论文，并促进全球变化科学教育和跨学科研究的持续外联工作。

The total soil organic carbon (SOC) in the northern permafrost zone is estimated to be more than twice as much C as is in the atmosphere. The accumulation of this SOC is driven by the cold climate limiting decomposition. Climate models predict that the Arctic will warm over the next century, therefore accelerating microbial decomposition of SOC is one of the most significant potential greenhouse gas release feedbacks from terrestrial ecosystems to the atmosphere. Winter snow cover and spring thaw are particularly important in influencing decomposition. Few studies, however, have explored how long-term warming will affect the seasonality of soil biogeochemical dynamics. To address this knowledge gap, this research project uses a greenhouse experiment initiated in 1988 at the Toolik, AK Long Term Ecological Research site to explore the consequences of long-term warming on Arctic soil microbial dynamics and nutrient cycling through repeated sampling across seasons and soil horizons. Bacterial and fungal communities? DNA will be studied, to characterize phylogenetically how different organisms respond to long-term warming across seasons and soil horizons. This work is being used to develop and parameterize a mechanistic model of tundra soils? responses to warming.Broader impacts: The data and model that grows from them are part of a multi-institute collaborative effort supported by the Arctic System Science Program's ?Changing Seasonality in the Arctic System initiative.? The model directly links the structure and activity of the Arctic microbial community to C and nutrient cycling, increasing our ability to predict how biogeochemical cycling in this system will respond to rapid climate warming. Additionally, any pyrosequencing-derived sequences generated through this project will be added into the NIH GenBank database. In addition to scientific collaborations, this project will foster the development of several students in the biogeochemical sciences, including two female undergraduates and a minority high school student, as well as supported participation in several science outreach projects targeted to the local K-12 community. The NSF DDIG grant will enhance the completion of a doctoral dissertation by a female scientist, as well as promoting continued outreach efforts in global change science education and cross-disciplinary research.