IIMYC   23581
INSTITUTO DE INVESTIGACIONES MARINAS Y COSTERAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Modern pollen, diatom, and chironomid assemblages as quantitative indicators for the reconstruction of past environmental conditions in the south-central Chile
Autor/es:
JARPA L; TONELLO M S; ABARZUA A M; MARTEL-CEA A
Lugar:
Zaragoza
Reunión:
Congreso; 5th Open Science Meeting - Pages; 2017
Resumen:
Quantitative reconstructions from biological proxies have revolutionized paleolimnology and paleoclimatology to allow us understand and compare different trends, magnitudes and timing during the Quaternary. Pollen, diatom, and chironomid assemblages were studied in the surface sediments of 62 small lakes and swamps along an altitudinal gradient from sea level to 1800 m in south-central Chile (37- 42°S). In addition, 27 environmental variables relating to the physical limnology, geography, climate, and water chemistry were recorded for each site. The explanatory power of each variable for the different biological data-sets was estimated by canonical correspondence analyses (CCA). A minimal set of environmental variables was found preliminary for each biological data-set by a forward-selection procedure within CCA. As the first step, inference models for austral winter air temperature (July) were developed for modern pollen data-set using weighted averaging partial least squares. This model was applied to the 26,000 yr BP time window addressed by the high resolution Lago Espejo pollen record (39°S, 400 m asl).The winter temperature reconstruction suggests 3-4°C during the LGM until 18,000 yr BP, when winter temperatures increase abruptly to10.5°C at 14,000 yr BP. Pleistocene?Holocene transition (12,500?11,500 yr BP) is marked by warm winter temperatures up to 11°C and high fire activity under warm conditions. Although, YDC is observed as the decrease of winter temperature on 1°C between 13,000 to 11,500 yr BP. Early and mid Holocene had winter temperatures between 10 to 8°C, until 3000 yr BP when winter temperatures drop to 5°C, close to the modern values. These results will be contrasted to different biological data-sets to integrate the paleolimnological and paleoclimatological reconstructions in south-central Chile, and their relationship with regional, inter-hemispheric, and global climate trends.