Surface soil characteristics for six thermokarst chronosequences near Toolik Field Station and Noatak National Preserve, Alaska

Surface organic and mineral soil layers were sampled in retrogressive thaw slump disturbance scars and nearby undisturbed tundra to estmate the influence of this thermo-erosional--thermokarst--disturbance type on soil carbon (C) and nitrogen (N) pools. Within six independent sites, we identified multiple thaw slump scars and determined time after disturbance for each scar by (1) aging the population of tall deciduous shrubs rooted in the mineral soil and (2) by dating the basal layer of the re-accumulating soil organic matter. Within each scar or paired undisturbed tundra site, we sampled replicate soil profiles volumetrically and analyzed samples for horizon depth, coarse, fine and rock fractional contribution, pH, bulk density, moisture content, and C and N concentration.

本研究针对退化热融滑塌（retrogressive thaw slump）扰动疤痕及邻近未受干扰的苔原，采集表层有机土层与矿质土层样品，以评估该热侵蚀-热喀斯特扰动类型对土壤碳（C）与氮（N）库的影响。在6个独立样地中，我们识别出多处热融滑塌疤痕，并通过两种方法确定各疤痕的扰动后时长：其一，对扎根于矿质土壤的高大落叶灌木种群进行年龄测定；其二，对再积累的土壤有机质底层进行年代测定。在每个滑塌疤痕或配对的未受干扰苔原样地内，我们按体积法采集重复土壤剖面，并对样品开展如下指标分析：土层厚度、粗颗粒、细颗粒及岩石的体积占比、pH值、容重、含水量，以及碳、氮浓度。