Pollen-vegetation relationships of the coastal dune system of southeastern Buenos Aires, Argentina, and its relevance for past vegetation changes modeling

VASQUEZ PEREZ, CAROLINA; SOTTILE, GONZALO; STUTZ, SILVINA

Bariloche

Encuentro; PRE - IAL IPA. ECR Virtual meeting; 2022

This project aims to establish the relationships between vegetation and the pollen spectra represented in the surface sediments of interdune lagoons of the Coastal Dune System (CDS) of the southeastern Buenos Aires, Argentina. The study of modern pollen-vegetation relationships is the first step for modeling the dynamics of vegetation during the last 500 years, considering exotic plant species introduction during the last 200 years. We took 22 surface samples from interdune lagoons to analyze pollen content. At each sampling point we performed four concentric vegetation surveys at 10 and 20 m. With this extrapolated information we generated maps using Google Earth images up to 2000 m radius, in which we identified different areas according to vegetation cover and geomorphology: Exotic forest, Interdune, Fixed, Semi-fixed and Mobile dunes, Distal beach, Beach, Lagoon, Sea and Infrastructure (human constructions). Sediment samples were treated according to standard techniques to obtain pollen grains.Multivariate analysis, unconstrained clustering and PCA, of surface pollen samples showed two major groups, one which includes sites/lagoons near exotic forest, characterized by the high presence of PINACEAE (16-43.1%) accompanied by ASTERACEAE-Ambrosia/Xanthium type (24-32.9%); and another group which includes sites/lagoons located in pristine dunes that shows mixed Interdunes, Fixed, Semi-Fixed and Mobile dunes areas, and registered low presence of PINACEAE (