Abstract

BERTOLAMI, Miguel A.; RUETER, B. L.  and  BENITEZ, M.. Analysis of compensated biological spectra in pampas of South-East of Chubut province. Multequina [online]. 2008, vol.17, n.2, pp.93-107. ISSN 1852-7329.

Dwarf shrubs and herbaceous  steppes are the dominant physiognomic types in Pampa Vaca (Central District), southeastern Chubut, while shrubs and herbaceous steppes dominate in Pampa Salamanca (San Jorge Gulf  District), but the latter with variable proportions of dwarf shrubs, shrubs and grasses. The aims of this  study were 1) to describe the life forms spectra in both "pampas" and 2) to report the seasonal fluctuations in green, dry and dead biomass sorted into life forms. Chi squared test (X²) was used to compare the spectra obtained with the Normal  Biologic Spectrum of Raunkiaer. Finally the spectra obtained were related to the climate of the area. A total of 28 species, belonging to 10 families, were recorded in Pampa Vaca; most of the species were Poaceae and Asteraceae. The dominant life forms were Chamaephytes (dwarf shrubs) and Hemicryptophytes (graminoids). Significant differences (α< 0,05) were obtained when the observed and theoretical biologic spectra were compared. The seasonal fluctuation showed that the Chamaephytes green biomass was related to wet years. In Pampa Salamanca a total of 80 species, distributed in 25 families, was found and similarly to Pampa Vaca, the Poaceae and Asteraceae were the richest families. The dominant life form was the Nanophanerophytes (shrubs), followed by the Chamaephytes and Hemicryptophytes. Highly significant differences were observed for  Nanophanerophytes and Chamaephytes when the observed and theoretical  biologic spectra were compared. According to the seasonal fluctuation observed in the biomasa data, it is assumed that the Hemicryptophytes green biomass had a better response to the rain.

Keywords : Functional type; Biomasa; Climatic conditions; Patagonian steppe.

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