Efectos del fuego y del pastoreo sobre la regeneración por semillas de Paspalum quadrifarium en la Pampa Deprimida, Argentina
Abstract
Fire and grazing by cattle are two basic management tools of the tall grasslands dominated by Paspalum quadrifarium (“pajonales”) in the Flooding Pampa, Argentina. We assessed the effect of burning and grazing on the seed bank, and on the recruitment and survival of seedlings of P. quadrifarium. Seed availability was significantly reduced by burning. However, seedlings were only observed in the burned treatments, where the canopy was more open. The proportion of seeds reaching the seedling stage was high in the burned treatments (burned: 0.26; burned and grazed: 0.84). Survivorship after two growing seasons was significantly higher under the combination of both burning and grazing (which determined the highest light availability). These results indicate that, at least within the undisturbed patches of “pajonal”, recruitment of P. quadrifarium depends on microsite availability, which is enhanced by fire in combination with grazing. However, because of both the inhibitory effect of fire on flowering and the absence of a permanent seed bank, seedling recruitment might be limited by seed availability after frequent burnings.
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