LATE HOLOCENE ECOLOGICAL AND CLIMATE CHANGE FROM PEAT RECORDS IN THE WESTERN ANTARCTIC PENINSULA

The Western Antarctic Peninsula (WAP) has experienced rapid warming over the past 50 years. The marine record from nearby Palmer Deep shows large magnitude changes in climate during the last 3,000 years. However, the response of terrestrial ecosystems to these changes is poorly understood. Peat deposits accumulating in permafrost-influenced moss banks in the Maritime Antarctic preserve a terrestrial record of past ecology and climate. Here we present a paleoecological record of ecosystem change derived from an 80 cm core collected from a peat bank on Litchfield Island (-64.77, -64.09) near Palmer Station. Chronology is established using Bayesian statistical age modeling of six AMS ¹⁴C dates with a basal age of 2,580 cal years BP. Age modeling shows that vertical accumulation of the peat bank ranges from 0.15 to 1 mm yr^-1 with a mean of 0.3 mm yr^-1. Macrofossil analysis results show that species dominance shifts between Polytrichum strictum, Chorisodontium aciphyllum and Pohlia sp in ca. 600 year cycles. Bulk density and LOI results show that carbon accumulation rates range from 8 to 92 gC m^-2yr^-1 with a mean of 22 gC m^-2yr^-1. There are marked periods of increased carbon accumulation over the past 350 years as well as a pronounced peak around 1,400 cal years BP. Oscillations of species dominance are interpreted as changes in local temperature or moisture availability due to climate change, as opposed to ecological succession. This new record shows the banks are highly dynamic ecosystems sensitive to climate and environmental changes. Increases in carbon accumulation rates in the past 350 years are likely due to increased production in response to more hospitable conditions in the WAP.