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

北极冻土带覆盖了大约6%的地球陆地表面，但却储存了世界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；对这种反馈进行适当的建模需要关于是什么控制了北极土壤中的碳循环的信息。到目前为止，大多数关于北极碳循环的研究忽略了北极动物在控制土壤生物地球化学循环中可能发挥的作用。动物可能影响这些循环的一个重要方式是通过建造洞穴、步道、厕所和巢等结构，每一种结构都扰乱土壤并改变其生物地球化学。此外，由于每个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会导致北极土壤循环的变化。该项目将食草动物结构和群落变化这两个因素结合在一起，研究其中任何一个因素的变化可能如何影响北极生态系统的碳和养分循环。这项研究正在扩大我们对北极系统的理解，并可用于改进对北极可能如何应对环境变化的预测。该项目包括对K-12岁和大学生的指导，在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扮演生态系统工程师的角色，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什么机制影响养分的可获得性和微生物的活动。研究人员还在评估两种相互竞争的小型哺乳动物物种(棕色狐猴和衣领狐猴)在功能作用和丰富度方面的差异可能会如何改变土壤的生物地球化学循环。在阿拉斯加州乌特基亚ġvik附近，研究人员正在从四种类型的小型哺乳动物结构(跑道、冬巢、厕所和洞穴)下采集土壤样本，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，然后使用这些数据来模拟每一物种在其种群周期高峰期的影响。这项研究将食草动物纳入到对北极生态系统功能的更好理解中，并被用来改进先前存在的生态系统模型，以更好地预测北极的碳循环。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。

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.