Origin of plant organic matter in permafrost revealed by ancient DNA and pollen analyses

• Main Authors: Zimmermann, Heike, Raschke, Elena, Epp, Laura, Stoof-Leichsenring, Kathleen, Schwamborn, Georg, Schirrmeister, Lutz, Overduin, Paul, Herzschuh, Ulrike
• Format: Conference Object
• Language: unknown
• Published: 2016
• Subjects: Arctic; Khaya; Buor-Khaya; Ice; permafrost; Tundra; wedge*; Siberia
• Online Access: https://epic.awi.de/id/eprint/41954/; https://hdl.handle.net/10013/epic.48768

Ice-rich permafrost deposits store large quantities of plant organic matter and are highly sensitive to climate warming. With rising ground temperatures they will increasingly act as a substrate for microbial turnover to greenhouse gases, which can further enhance climate warming. To assess the future fate of the Arctic region, a better characterisation of plant organic matter is thus necessary. We applied ancient DNA-metabarcoding and pollen analyses at high resolution on an 18.9 m long permafrost core from the Buor Khaya peninsula (North-Eastern Siberia). Our aim was to reconstruct past local to regional flora to assess the taxonomic origin of plant organic matter and the environmental conditions during the time of accumulation. The core consists of two segments, which are divided by an ice-wedge: (1) Yedoma deposits (51-44 kyr BP, fine-grained, ice-rich permafrost with average total organic carbon contents (TOC) of 2.7 wt. %) and (2) a Late Glacial to Early Holocene cover (11-10 kyr BP, average TOC of 3.5 wt. %). With DNA metabarcoding we detected 112 terrestrial and 21 swamp and aquatic plant taxa, of which 81 % are identified to genus or species level. The taxonomic composition of Yedoma suggests an accumulation of organic matter in shallow water within a low-centred ice-wedge polygon. The pollen analyses support these findings but imply relatively arid environmental conditions on a regional scale. During the Late Glacial to Early Holocene transition the compositions recorded by both proxies indicate shrub tundra with more humid environmental conditions on a local to regional scale.