Stable tundra vegetation on the Yukon Coastal Plain (NW Canada) during the last three centuries inferred from a thermokarst lake record

• Main Authors: Wolter, Juliane, Lantuit, Hugues, Herzschuh, Ulrike, Fritz, Michael
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Thermokarst; Tundra; Yukon
• Online Access: https://epic.awi.de/id/eprint/38535/; https://hdl.handle.net/10013/epic.45855

Climatic change during historic times and their environmental impact are little known for much of the North American Arctic. Instrumental records from the Yukon Coastal Plain have a high uncertainty due to the remoteness of the region and the extreme climatic conditions. We present a data set with about decadal temporal resolution reaching back to the early 1700s. We analyzed a short sediment core from a thermokarst lake on the Yukon Coastal Plain in the Canadian Low Arctic for pollen, 210Pb/137Cs, grain size distribution, stable carbon isotopes, and carbon and nitrogen contents. 210Pb/137Cs dating results show a chronological age-depth relationship and provide a high temporal resolution for the last 70 years. We found no regional vegetation change in the pollen record. Ordination methods do not reveal any changes in ecological groups or a stratigraphic gradient. The minor increase in Alnus pollen during the last century points to an approaching Alnus shrubline. Biogeochemical analyses show changes in organic carbon content and carbon to nitrogen ratio that we attribute to local hydrological changes. The lake level seems to have been lower and more variable pre 1900. Short-term climatic fluctuations have not been verified for the Yukon Coastal Plain, but on a larger spatial scale cooler and warmer periods have been found during the last 300 years. The recent regional warming trend started in the mid 1970s. The small change in the pollen record during the last 30 years could reflect a time lag between climatic change and vegetation response. We infer that there was only little climatic change in the study area during the last 300 years and its effects were buffered within the ecosystem.