Pollen dispersal over complex terrain: How does anisotropic airborne pollen transport affects interpretation of fossil pollen records? A case study in Northern Patagonia

PÉREZ CF, BIANCHI MM, GASSMANN MI, TONTI N AND PISSO I

Viena

Otro; European Geosciences Union General Assembly 2014; 2014

EGU

Accumulated pollen in stratified fossil reservoirs is used to infer temporal changes in vegetation composition. Transport and dispersal by winds are known to introduce large biases in the interpretation of pollen records. In order to calibrate the models used to infer information about past species distributions, human activities and climate, contemporary time series of pollen records are assessed and modeled. In this study we analyse airborne pollen measurements collected at Bariloche, Argentina (41°10´ lat. S, 71°15´ long. W; 850 m elevation) of the species Weinmannia trichosperma, a characteristic forest tree which grows only in the western slopes of the Andes. Instead of the simplistic Gaussian plume mixing model that is usually employed in the theory of pollen analysis we apply a full 3D Lagrangian dispersion model to interpret the observations and assess the impact of long range transport over the Andean mountain range. The Lagrangian footprint calculation of the air masses origins are consistent not only with the Chilean Weinmannia pollen measurements but also with a characteristic set of species found on the dryer steppe located to the east of the site. The agreement of the modeling results indicates that significant interpretation mistakes may arise from inconsistent transport modelling. The further application of inverse trajectory modeling to the estimation of the source intensity is discussed.