Aerobiological study in an urban area of the main fluvial wetland region of Argentina

LATORRE, F. ; FAGÚNDEZ, G., MUÑOZ, N. & SÁNCHEZ, A.

Buenos Aires

Congreso; 9th International Congress on Aerobiology; 2010

The first continuous aerobiological monitoring of the fluvial wetland region from Paraná river (Argentina) was established at Diamante city in 2005. This city is next to the Pre-Delta National Park founded to protect natural vegetation and where flora from Espinal, Pampa and Paranaense Phytogeographical Provinces converge. The main objective was to determine the diversity of airborne pollen grains and to relate them to plant sources and floral phenology dynamics. Pollen data were obtained applying a continuous and volumetric methodology, using a Hirst trap (Lanzoni). The data from the urban vegetation derived from a census performed, and the information from natural plants arose from specialized bibliography as well as from personal observations. A phenological survey from tree species was conducted to compare it with airborne pollen curves. The most abundant pollen types in the air in decreasing order of importance were as follows: Moraceae (with 60% of the annual total pollen, ATP), Poaceae, Cupressaceae, Fraxinus, Salix, Asteraceae Asteroideae, Celtis, Ambrosia, Artemisia, Urticaceae and Cyperaceae. Each one of these taxa reached at least 2% of the ATP. All of them, together with Platanus, amounted to 76% of ATP, without considering Moraceae. The relationship of total pollen with temperature was positive, whereas with humidity, it was negative. This could be ascribed to the flowering seasonality of the main plants, with a maximum in October and a minimum in June when the lowest temperatures of the year occur. Urban arboreal vegetation showed a great diversity with 41% of taxa present in the atmospheric spectrum; the most abundant species were mainly entomophilous: Tabebuia impetiginosa, Tecoma stans, Lagertroemia indica. Native flora was an important pollen source, mainly Celtis, Phytolacca dioica, Salix and Cyperaceae. Fraxinus pennsylvanica was the most abundant species, with respect to the 34% of anemophilous urban trees.  Though being exotic, this species has been naturalized in this region. The daily pattern of Fraxinus pollen showed a maximum at 14:00 (13% of total) with relatively high values until evening; this supports the hypothesis of both local and regional origins; Moraceae presented similar results. F. pennsylvanica yielded a high intraspecific variability on floral development, mainly in the maximum phase. Nevertheless the pollen curve was coincident with the mean flowering one.  A depressor effect was observed in pollen concentrations.