Vegetational survey of species asociated to productive activies in the upper valley of Río Negro and Neuquén.

The actual trend to crop diversification (vegetables, aromatics, fine-fruits, seed production) in which weeds have more incidence than in fruit trees, showed the necessity to begin studies to know the species that behave like weeds, as well as the possible way of entrance to the region. The objective of this work was to know the floristic composition and presence of weeds in the Valley of Río Negro and Neuquén. Employing the Braun Blanquet method, the inventories were made for each season in 25 plots distributed in 14 sites. In non cultivated areas (routes, rail roads, wastelands) the species present were registered by mean of previously determined rounds. The result was a list of 158 species distributed in 31 families. The families with the longest number of representatives were: Poaceae with 39 species, Asteraceae 31, Brassicaceae 14, Chenopodiaceae 11 and Fabaceae 8. Dicotyledons represent 71 % and Monocotyledons 29 %. The presence of 6 species unnoticed before for the region was established. The information obtained could be useful in further works to established changes in floristic composition and hierarchy of species that compound the weed community.

Key words: Weeds, Vegetation, Inventory, Alto Valle.