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Heterogenity of the vegetation of basaltic environments in central Argentina. The flora and the vegetation of basaltic outcrops of Los Cóndores Mountains, central Argentina, are described. Plant communities were sampled following the Braun-Blanquet methods. The 98 relevés × 272 species matrix was classified through the ISOPAM method. The classification discriminated three main communities occurring in the three different substrates explored in this landscape: Rocky Islands (inselbergs), a Natural Matrix surrounding the Islands and an Agricultural Matrix, surrounding the whole basaltic area. The three communities differed in composition and physiognomy: the Islands were the less disturbed sites, reporting the highest plant species richness and diversity as well as the higher number of endemics, and the lowest number of exotic species. In the other extreme of the disturbance gradient, the Agricultural Matrix showed the opposite patterns and is dominated by annual and perennial herbs, mainly weeds. While the number of aliens is low in the Islands and in the Natural Matrix, almost 50% of the species are exotic in the Agricultural Matrix. The results of this study reveal that the basaltic inselbergs are relevant sites for the conservation of the natural heritage. [ABSTRACT FROM AUTHOR]

The flora and the vegetation of basaltic outcrops were studied in central Argentina. Coverabundance scores were recorded for 303 plant species in 48 relevés distributed in four outcrop locations ranging between 400 to 900 m asl. The association between the floristic composition and climatic variables were explored through an ordination analysis, and the vegetation of the outcrops was classified into four major types through a classification technique. The floristic composition of the outcrops was significantly associated to climate at the regional scale and the four sites differed in species richness, diversity and dominance. We conclude that well conserved basaltic outcrops from central Argentina are relevant habitats for the conservation of endemic species and over exploited taxa. [ABSTRACT FROM AUTHOR]