Ground Penetrating Radar data surrounding beaver ponds in Alaska tundra, 2021

In recent decades, beavers have reportedly extended their range from the boreal forest into the arctic tundra, altering tundra streams and surrounding permafrost at local to regional scales. In lower latitudes, beaver damming can convert streams, backwaters, and lake outlets into connected ponds, which in turn can change the course of channels, temperature of streams, sediment loads, energy exchange, aquatic habitat diversity and nutrient cycling, and riparian vegetation. In the Arctic, effects of beavers may include enhanced thawing of permafrost, increased stream temperatures, and changes in seasonal ice in streams, as well as complex ecosystem responses. This study will 1) document movement of beavers from the forest into tundra regions, 2) understand how stream engineering wrought by beavers will change the arctic tundra landscape and streams, and 3) predict how beavers will expand into tundra regions and alter stream and adjacent ecosystems. Results will be of interest to local communities and resource managers, and the team of investigators will convene a scientist and stakeholder workshop in Fairbanks, Alaska to synthesize observations, compare results from studies in temperate ecosystems, and clarify impacts of beaver expansion unique to the tundra biome. In August 2021 we used a ground penetrating radar (GPR) to image the subsurface surrounding beaver ponds in a tundra region around Nome, Alaska. The general objective was to determine if heat from new beaver ponds are impacting permafrost. We used a Mala GX GPR (Mala Ground Explorer GPR) with a 450mhz antenna and an integrated DGPS (differential global positioning system). GPS (global positioning system) location data is stored in the .cor file.

近数十年来，据报道河狸（beaver）的分布范围已从北方针叶林（boreal forest）扩张至北极冻原（arctic tundra），在局地乃至区域尺度上改变了冻原溪流与周边永久冻土（permafrost）的状态。在低纬度区域，河狸筑坝可将溪流、回水湾与湖泊出水口连通为连片池塘，进而改变河道走向、溪流水温、沉积物负荷、能量交换过程、水生栖息地多样性与养分循环，以及河岸植被群落。在北极地区，河狸的生态影响可能包括永久冻土解冻加剧、溪流水温升高、溪流季节性冰况变化，以及复杂的生态系统响应。本研究旨在达成三项目标：1）记录河狸从森林向冻原区域的扩散动态；2）阐明河狸的溪流改造工程将如何改变北极冻原景观与溪流生态系统；3）预测河狸向冻原区域扩张的趋势及其对溪流与邻近生态系统的影响。本研究结果将对当地社区与资源管理者具有参考价值，研究团队将在阿拉斯加州费尔班克斯举办科学家与利益相关者研讨会，以整合观测数据、对比温带生态系统的相关研究结果，并明确河狸扩张对冻原生物群区（tundra biome）的独特影响。2021年8月，我们使用探地雷达（ground penetrating radar, GPR）对阿拉斯加州诺姆周边冻原区域内的河狸池塘周边地下结构开展成像工作，核心目标为验证新建河狸池塘的热效应是否会对永久冻土造成影响。本次研究使用搭载450MHz天线的Mala GX探地雷达（Mala Ground Explorer GPR）及集成差分全球定位系统（differential global positioning system, DGPS），全球定位系统（global positioning system, GPS）定位数据存储于.cor格式文件中。