Vegetational and climatic history during the late Holocene in Lake Laja basin (central Chile) inferred from sedimentary pollen record

This study reports a pollen analysis from Lake Laja, an Andean lake in central Chile, from 800 cal. yr BC to present. A 522-cm core was taken from the deepest part of the lake and pollen was analyzed according to conventional methods. The core was dated using 210Pb and 14C techniques. Lake Laja is located at 1360 masl, next to Antuco volcano and, due to the westerly circulation belt, the predominant climate in the area is humid-temperate and cool. Interannual climate variability is related to El Niño-Southern Oscillation. Currently, the vegetation cover is 53% native forest, 27.8% shrub, 16% Andean steppe, and 3.2% annual and perennial prairies. The study results indicated that Nothofagus dombeyi-type, Nothofagus obliqua-type, Ephedra chilensis, and Poaceae were the most important taxa during the last 2800 yr BP. The climate was slightly less humid between 800 cal. BC and 660 AD than at present. Between 660 AD and 1561 AD, humid conditions increased with respect to the previous period. Later pollen records evidenced a drier period between 1561 and 1894 AD, corresponding to the last phase of the LIA in Europe. Finally, between 1938-1968 AD, intense human impacts were evidenced by the appearance of Plantago and the increased frequency of Poaceae and Asteraceae. After 1968 AD, the pollen records show decreased anthropic disturbances, as well as increased humid conditions.