Active Layer/Landscape Interactions: A Retrospective and Contemporary Approach in Arctic Alaska

该项目通过研究土壤活动层厚度的空间(局部和区域)和时间(年际到年代际)变化，解决了北极系统科学LAII通量研究的中心假设。这是通过使用不同的探测和土壤取心方法(栅格、横断面和点数据)在典型景观上完成的。标准的1千米x 1千米网格位于阿拉斯加北极坡的不同景观单元中。LAII站点由其他通量研究项目共享，在大多数情况下是根据包括土壤融化和当地气候记录在内的长期数据集的可用性来选择的。这项研究依赖于根据气候、土壤特性和景观单元(地球植物复合体)对活动层厚度进行高频、特定地点的测定。通过对冻土取心，观测地面冰的分布和形态，建立了冻土融化地基与上冻土之间的历史分界线。融化深度测量用于验证或修改活动层模型，并评估北极冻土带生态系统的气候变化。土壤和近地表冻土的碳状况是通过景观单元确定的，并作为区域尺度碳平衡外推的基础。

This project addresses the central hypotheses of the Arctic System Science LAII Flux Study by examining spatial (local and regional) and temporal (interannual to interdecadal) variations in soil active layer thickness. this is done on representative landscapes by using different probing and soil coring approaches (grids, transects, and point data). Standard 1 km x 1 km grids are located in different landscape units across the Alaska Arctic Slope. the LAII sites, which are shared by other Flux Study projects, were selected in most cases based on availability of long-term data sets including soil thaw and local climate records. The study relies upon high frequency, site specific determination of active layer thickness as a function of climate, soil properties, and landscape units (geobotanical complexes). the historical boundary between the base of the recelt soil thaw and the upper permafrost is established by coring the frozen ground and observing the distribution and morphology of the ground ice. The thaw depth measurements are used to validate or modify active layer models and to assess climate change upon the arctic tundra ecosystem. The carbon status of the soils and near-surface permafrost are established across landscape units and serve as a basis for carbon balance extrapolations to regional scales.