Abstract

GONZALEZ LOYARTE, María M. Relationship among grain-size, plant communities, and fluvial and eolian processes in a piedmont of the central Andes in Argentina. Ecol. austral [online]. 2003, vol.13, n.1, pp.27-48. ISSN 1667-782X.

The relationship among modern geomorphological processes, grain-size of surface sediments, and vegetation was analyzed in an alluvial fan in the piedmont of the Cordillera Frontal (Andes Mountains). Statistical parameters of grain-size distribution were calculated according to a standard graphical method. Plant communities were studied by applying a standard floristic-ecological method. A sensitivity analysis of grain-size parameters and plant communities in relation to geomorphological processes was made, based on literature, to compare results. Indicator species of fluvial, eolian and soil erosion processes were identified. Contemporary surface modifications by fluvial and eolian processes produce distinct surface sediment size parameters (mean diameter, standard deviation, skewness and kurtosis). The vegetation pattern follows these differences since communities with riparian species (Proustia cuneifolia var. mendocina and Eupatorium buniifolium) characterize the terraces and the young alluvial fan with fluvial processes, and psammophytes (Grindelia chiloensis, Aristida subulata, Poa lanuginosa, Glandularia parodii) characterize different communities developed under eolian activity.

Keywords : Grain-size analysis; Plant communities; Fluvial/eolian processes; Phytosociology; Indicator species.

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