Late-Holocene and Little Ice Age palaeoenvironmental change inferred from pollen analysis, Isla de los Estados, Argentina

PONCE, J. F.; BORROMEI, A.; MENOUNOS, B.; RABASSA, J

QUATERNARY INTERNATIONAL

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2017 vol. 442 p. 26 - 34

1040-6182

We present pollen and spore analysis from a peat-bog section from southwestern Isla de los Estados(Staaten Island), Tierra del Fuego to better understand late-Holocene environmental change in southernmostPatagonia. The island's position as the easternmost landmass at the southernmost of SouthAmerica, places it squarely within the influence of the southern westerly winds (SWW) and the AntarcticCircumpolar Current, and so makes the island a unique location to document the palaeoecologicalresponse to climate change during the late Quaternary. We compare our Nothofagus pollen record fromBahía Franklin with other Nothofagus pollen records from Isla de los Estados and Tierra del Fuego.Nothofagus has been shown to respond to changes in mean annual temperature in the southern latitudesunder cooler climate with little seasonality in precipitation. We also evaluate the correspondence betweenthese changes in vegetation to other late-Holocene environmental proxies that include variationsin sea surface temperature (SST) from the Beagle Channel and records of past glacier fluctuations. Ourresults show that low concentrations of Nothofagus pollen existed at Bahía Franklin at about 4000 cal yrBP. Climate ameliorated between ca. 3500 and 500 cal yr BP based on an increase in frequency andconcentration values of Nothofagus and Drimys winteri. Between about 500 and 50 cal yr BP, the pollenrecord revealed a noticeable decline in the forest density.We interpret the decline in forest density in Islade los Estados between 500 and ~50 yr cal BP as a response to cold and windy conditions during the LittleIce Age (LIA). Our interpretation from our Nothofagus pollen record broadly agrees with regional coolingrecorded in reconstructed SST of the Beagle Channel and with glacier expansion in the Fuegian Cordillera.