Resumo

REQUESENS, Eduardo; MARTINEFSKY, María J  e  SCARAMUZZINO, Rosa. Weed seed bank along a micro-topographical gradient in an arable soil in Azul (Buenos Aires). Ecol. austral [online]. 2004, vol.14, n.2, pp.141-147. ISSN 1667-782X.

Community composition, size and structure of the weed seed bank were analyzed along a micro-topographical gradient of 175-m length and 12.5% slope located in an agricultural field in Azul (Buenos Aires). Three soil samples were collected from each of eight equidistant positions upon the gradient. Seeds in samples were isolated through washing and screening, identified and counted. The number of apparently viable seeds along the gradient ranged 19680-61280 seeds/m². The latter value was recorded in the lowest position upon the gradient, and resulted significantly higher with respect to those from the remainder positions. Chenopodium album, Amaranthus quitensis, and Digitaria sanguinalis were the most abundant species in the seed bank. The spatial distribution pattern of the two first species showed a variance-mean ratio of 17.28 and 15.80, respectively, with a tendency to aggregation in the lowest position of the gradient. The changes in species richness, evenness, and specific diversity along the gradient were not significant, but the last two parameters showed a negatively significant correlation with seed density.

Palavras-chave : Seed community; Seed density; Spatial distribution; Structure.

        · resumo em Espanhol     · texto em Espanhol     · Espanhol ( pdf )