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.

本研究于热融滑塌（retrogressive thaw slump）扰动瘢痕区域及周边未受干扰的苔原（tundra）中采集表层有机土层与矿质土层样品，以评估这类热侵蚀-热喀斯特扰动类型对土壤碳（C）、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扰动瘢痕，并通过两种方法确定各瘢痕的扰动后时长：其一，对扎根于矿质土层的高大落叶灌木种群进行年龄测定；其二，对再堆积土壤有机质的基底土层进行定年。在每个扰动瘢痕或配对的未受干扰苔原样地中，我们按体积法采集重复土壤剖面样品，并分析了样品的土层厚度、粗颗粒占比、细颗粒占比、岩石碎屑占比、pH值、容重、含水量以及碳、氮浓度。