Quantitative analysis of pollen and vegetation richness relationship at the southeastern Buenos Aires coastal dune system

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

Bariloche

Congreso; IAL IPA 2022 Lagos Memorias del Territorio; 2022

IAL/IPA

This project aims to evaluate the relationship between plant and pollen richness of the Coastal Dune System (CDS) of the southeastern Buenos Aires, Argentina, associated to taxonomic and taphonomic constraints on pollen production, preservation and dispersion at local and landscape scales. Pollen analysis is a widely used tool in paleoecology to reconstruct both vegetation history and to analyze temporal changes in plant diversity. However, pollen abundance cannot be directly translated into plant abundance in the vegetation when interpreting past pollen assemblages. To overcome this issue, it is necessary to improve past plant diversity reconstructions by calibrating modern pollen-vegetation diversity relationships, by studying pollen surface samples to understand fossil pollen assemblages and their ecological signifcance. We took 21 pollen surface samples from interdune lagoons to analyze their pollen content and its relationship with the surrounding vegetation cover at different radii (5, 10, 20, 1000, 2000 m). Sediment samples were treated according to standard techniques to obtain pollen grains. Vegetation cover was calculated by feld measurements at 5, 10 and 20 m. We took local vegetation information to generate vegetation maps at 1000 and 2000 m radii from the pollen surface samples point. Plant richness and pollen surface samples were analyzed through linear regression models and multivariate analysis. We fInd positive and close correlation between plant richness and their pollen equivalents (adjusted r2= 0.5116). Also, we fnd a positive and signifcant correlation between pollen surface sample richness and plant richness at 20, 1000 and 2000 m. Multivariate analysis relates high pollen surface sample richness with sites partially covered by Pinus and other alien tree and herbs communities, within to 2 km radii. These preliminary results shows quantitatively that there is a positive relationship between plant and pollen richness at local (20 m), extra-local (landscape) and regional scales in the CDS. However, the Adjusted R-squared is smaller at 2 km distance with respect to 20 m. This patter suggest that these models ft better assuming smaller Relevant Pollen Source Area.