Presentation of urban trees in the pollen spectrum of Santa Rosa, La Pampa (Argentina)

CARAMUTI, V. E.; NAAB, O. A.; VILLAMIL, C. B.; MURRAY, M. G.

Buenos Aires

Congreso; 9th International Congress on Aerobiology; 2010

International Association for Aerobiology

The aim of this work was to establish the representation of urban trees in the tree fraction of the aeropolinic spectrum from Santa Rosa city, capital of La Pampa province. A census was taken of the street trees in an area of 2.25 km2  and a pollen sampler was placed in the centre of the area which captures pollen from local, extralocal, regional and extraregional sources. The aeropolinic sampling was carried out with a Hirst Lanzoni volumetric sampler placed in the city centre at a height of 15m. Samples were taken daily during the pollen season July 2007 – June 2008. The relative abundance to the annual total (P) was calculated for each tree pollen type. Pollen types that occured as 0.3% of the total annual spectrum or more were considered and their corresponding relative abundance (V) and possible sources of emision were identified within the censured area. The index of representation V/P was calculated from these two parametres. Fifteen pollen types accounted for 57% of total pollen (98.3% tree pollen) and the most abundant was Cupressaceae (28.5%) which was over-represented (V/P < 0.77). Other over-represented pollen types were Styphnolobium, Myrtaceae, Platanus, Morus, Populus and Ailanthus. The over-representation of anemophilous taxa is common, whereas entomophilous taxa are only represented if they are near to the sampler. Equal representation (V/P > 0.77 and < 1.26) was shown by Olea-Ligustrum. This could be explained by the ample use of Ligustrum lucidum (V = 6,2%), of entomophilous pollination, on the sidewalk. Fraxinus, Ulmus, Arecaceae and Rosaceae were under-represented (V/P > 1,26). Fraxinus is the most abundant genus of urban trees (V = 36,5 %); the representatives of Rosaceae are also abundant, especially due to the use of Prunus ceracifera var. atropurpurea, of entomophilous pollination. Condalia and Nothofagus were not represented in the vegetation of the censured area. The contribution of the former might come from regional sources (calden woods) and the latter from extraregional sources (sub-antartic woods).