Vegetation response to fire and volcanic disturbances since the Late Pleistocene in the Southern Patagonian Andes (49°S)

MERINO CAMPOS V H; SOTTILE G D; DE PORRAS M. E.; TONELLO M S

Bariloche

Congreso; IAL IPA JOING MEETING 2022; 2022

High-Andean fossil records from the southeast Patagonian Andes (49°S) bring a uniqueperspective for analyzing past vegetation disturbances such as fires or tephra deposition aftervolcanic eruptions occurred since the Last Glacial Termination (T1) at the eastern margin ofthe South Patagonian Icefield. Pollen, charcoal and tephra records from two sedimentarysequences from high-Andean lakes were analyzed in order of evaluating potential changesin the vegetation as response to fire activity and tephra deposition from NAVZ (North AustralVolcanic Zone). Pollen data reveal Late Pleistocene to Holocene vegetation dynamics atLaguna Gemelas Este (LGE, 883 m.a.s.l., 49°23’06” S, 72°53’50” W), with high Andean taxadominating the area before 15,200 cal yrs BP. Then, between 15,200 and 4,600 cal yrs BP,the record shows the onset of Nothofagus forest establishment followed by the developmentof subantarctic forest as we know today. Laguna Chiquita (LCH, 987 m.a.s.l.; 49°22’22” S,72°58’28” W) pollen suggest a closed Nothofagus forest with no major changes of vegetationduring the last 500 cal yrs BP. Charcoal data reveal high fire activity peaks before 15,200,4500 and around 500 cal yrs BP at LGE and before 500 cal yrs BP and in modern times atLCH. LGE oldest and higher fire episodes are likely to be related to non-arboreal burnedmaterial due to scarcity of local Nothofagus forest presence in the area, while LCH firepeaks are probably linked to forest wood burning. Tephra deposition produced slightly lowerconcentrations of pollen in the sedimentary sequences, but no major changes in vegetationoccurred during/after these events, showing a high resilience of subantarctic forests to suchdisturbances.