Soil Seed Banks on Argentine Seminatural Mountain Grasslands After Cessation of Grazing

DIANA MARCO; SERGIO PAEZ

Mountain Research and Development

Año: 2000 vol. 20 p. 252 - 259

We studied the seed bank and aboveground vegetation in a replicated field experiment with sites ungrazed for 22 years as well as three different grazed sites in seminatural grasslands in central Argentina. We examined the relationship between vegetation and seed bank composition, and tested 3 hypotheses predicting decrease in seed bank richness, decrease in seed bank abundance, and divergence of seed bank species composition from vegetation composition during succession. Grazing changed species abundance and the vertical structure of the vegetation but did not cause loss of species. Most of the taxa in the seed bank occurred in the vegetation. Seed bank richness, diversity, and abundance decreased significantly during grassland succession following cessation of grazing. Although in general the most abundant species in the vegetation at each site were also dominant in the respective seed bank, seed bank and vegetation composition differed greatly after cessation of grazing. The seed bank at sites undisturbed over the long term does not appear to be an important source of seedling recruitment after disturbance in these grasslands.