Publication Date

1997

Description

The germinable seed bank was characterized in relation to season, grazing, and site type at southcentral San Luis, Argentina. Vegetation is typical of the semiarid western extreme of the Pampas grasslands. Our objective was to evaluate the effect of grazing and rest during the growing season on seed banks for two contrasting sites. Seed banks were sampled twice, in spring and fall. In each date, soil cores were obtained in sanddune and flat sites, for pastures grazed or that remained ungrazed during the growing season. Soil was spread in trays under suitable conditions for germination. Evaluations were done on total seed abundances, and abundance of dicots, warm-season grasses, and cool-season grasses. Seed numbers increased from spring to fall after completion of the growing season for all species groupings. Rest during the growing season increased the seed bank of warm-season grasses. Beneficial effects of rest are probably transient because of limited seed carry-over from season to season, particularly for cool-season grasses.

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Short-Term Effects of Grazing and Rest Treatments on the Seed Banks of Two Contrasting Sites in the Semiarid Pampas, Argentina

The germinable seed bank was characterized in relation to season, grazing, and site type at southcentral San Luis, Argentina. Vegetation is typical of the semiarid western extreme of the Pampas grasslands. Our objective was to evaluate the effect of grazing and rest during the growing season on seed banks for two contrasting sites. Seed banks were sampled twice, in spring and fall. In each date, soil cores were obtained in sanddune and flat sites, for pastures grazed or that remained ungrazed during the growing season. Soil was spread in trays under suitable conditions for germination. Evaluations were done on total seed abundances, and abundance of dicots, warm-season grasses, and cool-season grasses. Seed numbers increased from spring to fall after completion of the growing season for all species groupings. Rest during the growing season increased the seed bank of warm-season grasses. Beneficial effects of rest are probably transient because of limited seed carry-over from season to season, particularly for cool-season grasses.