COLLABORATIVE RESEARCH: Spatial and Temporal Influences of Thermokarst Failures on Surface Processes in Arctic Landscapes

Recent summaries of international research clearly document the past and future extent of climate warming in the Arctic. These summaries suggest that in the future, rising temperatures will be accompanied by increased precipitation, mostly as rain: 20% more over the Arctic as a whole and up to 30% more in coastal areas during the winter and autumn. These climate changes will have important impacts on Arctic Systems. Of direct interest to this research is the likelihood that warming will promote permafrost degradation and thaw. Formerly frozen soils may be further destabilized by increased precipitation, leading to hillslope thermokarst failures. Recent work has documented that thermokarst failures are abundant and appear to have become more numerous around Toolik Lake on the eastern North Slope and in the western Noatak River basin in Alaska. A widespread and long-term increase in the incidence of thermokarst failures may have important impacts on the structure and function of arctic headwater landscapes. This research will use a systems approach to address hypotheses about how thermokarst failures influence the structure and function of the arctic landscape. It will focus on the composition of vegetation, the distribution and processing of soil nutrients, and exports of sediments and nutrients to stream and lake ecosystems. Results obtained at this hillslope scale will be linked to patterns observed at the landscape scale to test hypotheses about the spatial distribution of thermokarst failures in the arctic foothills. It is important to understand these interactions because perhaps the greatest potential impacts of changing land surface processes and formation of thermokarst failures are feedbacks to the climate system through energy, albedo, water, and trace gas exchange. This research is designed to quantify linkages among climatology, hillslope hydrology, geomorphology, geocryology, community ecology of vegetation, soil nutrient dynamics, microbial ecology, trace gas dynamics, and aquatic ecology. It will employ a combination of field experimentation, remote sensing, and simulation modeling as a means to quantify these relationships.

国际研究的最新综述清晰记录了北极气候变暖的历史进程与未来发展幅度。此类综述指出，未来气温上升将伴随降水增加，且降水形式以降雨为主：整体北极地区降水将增加20%，冬季与秋季的沿海地区降水增幅可达30%。此类气候变化将对北极系统造成显著影响。本研究的核心关注点之一为，气候变暖或将加剧永久冻土（permafrost）退化与消融。原本封冻的土壤还会因降水增加进一步失稳，进而引发坡面热喀斯特塌陷（thermkarst failures）。已有研究证实，热喀斯特塌陷现象分布广泛，且在阿拉斯加北坡东部的图利克湖（Toolik Lake）周边与西部的诺阿塔克河（Noatak River）流域，该现象的数量呈上升趋势。热喀斯特塌陷发生率的大范围长期增长，或会对北极源头流域景观的结构与功能产生重要影响。本研究将采用系统论方法，围绕热喀斯特塌陷如何影响北极景观的结构与功能这一假说展开研究，将聚焦于植被组成、土壤养分的分布与循环过程，以及沉积物与养分向溪流与湖泊生态系统的输出通量。本研究将把坡面尺度下获取的研究结果，与景观尺度下观测到的格局相结合，以验证关于北极山麓地带热喀斯特塌陷空间分布的相关假说。厘清此类相互作用至关重要，因为地表过程改变与热喀斯特塌陷形成所带来的最大潜在影响，或许是通过能量、反照率（albedo）、水循环与痕量气体交换对气候系统产生的反馈效应。本研究旨在量化气候学、坡面水文学、地貌学、冻土学（geocryology）、植被群落生态学、土壤养分动力学、微生物生态学、痕量气体动力学与水生生态学之间的关联，并将结合野外试验、遥感技术与模拟建模手段，对上述关联进行量化分析。