Doctoral Dissertation Research: Examining the effects of small mammal structures and population changes on biogeochemical cycling in Arctic soils

北极苔原覆盖了大约6%的地球陆地表面，却储存了世界上25%的土壤碳。随着气候变暖，这些储存的碳被释放到大气中，进一步加剧了气候变暖；正确地模拟这种反馈需要关于什么控制北极土壤中的碳循环的信息。迄今为止，大多数关于北极碳循环的研究都忽视了北极动物在控制土壤生物地球化学循环方面可能发挥的作用。动物可能影响这些循环的一个重要方式是通过建造洞穴、小径、厕所和巢穴等结构，每一种结构都会扰乱土壤并改变其生物地球化学。此外，由于每种物种结构的影响可能不同，随着气候变暖，动物物种种群分布的变化可能导致北极土壤循环的变化。这个项目将这两个因素——食草动物结构和群落变化——结合起来，并研究两者的变化如何影响北极生态系统中的碳和养分循环。这项研究扩大了我们对北极系统的了解，并可用于改进对北极如何应对环境变化的预测。该项目包括对K-12和大学生的指导，北极社区的公共宣传，以及向公众传播科学。北极食草动物，包括小型哺乳动物，影响环境过程，反馈生态系统功能。虽然大多数研究都集中在食草动物的影响上，但小型哺乳动物也可能充当生态系统工程师，改变它们周围的生物物理环境。该项目正在研究小型哺乳动物的结构如何以及通过何种机制影响营养物质的可用性和微生物活动。研究人员还评估了两种竞争性小型哺乳动物（棕色和有领旅鼠）在功能角色和丰度上的差异如何改变土壤生物地球化学循环。在阿拉斯加Utqiaġvik附近，研究人员正在从四种小型哺乳动物的结构（跑道、冬季巢穴、厕所和洞穴）下面取样土壤，以检查它们对土壤生物地球化学反应的影响。利用每种活动类型在景观上的比例覆盖及其对生物地球化学循环的相对影响，然后利用这些数据来模拟每种物种在其种群周期高峰期间的影响。这项研究将食草动物纳入对北极生态系统功能的更深入了解，并被用于改进现有的生态系统模型，以更好地预测北极的碳循环。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Arctic tundra covers approximately 6% of the earth's land surface yet stores 25% of the world’s soil carbon. As the climate warms, this stored carbon is released to the atmosphere, further enhancing climate warming; properly modeling this feedback requires information on what controls the carbon cycle in Arctic soils. To date, most studies of the Arctic carbon cycle have neglected the possible roles played by Arctic animals in controlling soil biogeochemical cycles. One important way that animals may affect these cycles is by building structures such as burrows, trails, latrines, and nests, each of which disturbs the soil and alters its biogeochemistry. In addition, because the effects of each species’ structures may be different, changes in the population distribution of animal species as the climate warms may lead to changes in Arctic soil cycles. This project is combining these two factors – herbivore structures and community change – and examining how changes in either may affect carbon and nutrient cycling in Arctic ecosystems. This research is expanding our understanding of Arctic systems and can be used to improve predictions of how the Arctic may respond to environmental change. This project includes mentorships of K-12 and college-aged students, public outreach in arctic communities, and dissemination of science to the public.Arctic herbivores, including small mammals, impact environmental processes that feedback on ecosystem function. While most research has focused on effects through herbivory, small mammals may also act as ecosystem engineers, modifying the biophysical environment around them. This project is examining how, and through what mechanisms, small mammal structures influence nutrient availability and microbial activity. The researchers are also evaluating how differences in the functional roles and abundances of two competitor small mammal species (brown and collared lemmings) may alter soil biogeochemical cycling. Near Utqiaġvik, Alaska, researchers are sampling soils from beneath four types of small mammal structures (runways, winter nests, latrines, and burrows) from each species to examine their impacts on soil biogeochemical responses. Using the proportional cover of each activity type on the landscape and their relative impacts on biogeochemical cycling, the data are then used to model the impacts of each species during the peak of their population cycle. This research is incorporating herbivores into the greater understanding of Arctic ecosystem function and is being used to improve a pre-existing ecosystem model to better predict carbon cycling in the Arctic.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.