Effects of fire on the soil seed bank in a cerrado sensu stricto incentral Brazil

摘要

The objective of this work was to verify the impact of two fire events on the density of the seed bank of a cerrado sensu stricto. The study was carried out at the Reserva Ecológica do IBGE, 35 km south of the city of Brasília (15o55’S, 47o52’W). The samples were collected one day before and one day after the prescribed fires of August 1998 and 2000. The seed reserve in the soil samples was estimated by adding direct and indirect counting. The fires had a significant impact on the seed bank reducing momentaneously the density of mono and dicot seeds. However the seed densities before the fires in 1998 and in 2000 were similar. Thus it is likely that within two years after fire, the vegetation can assure the recovery of the seed bank. The greater proportion of monocot seeds in relation to dicots confirms the effect of frequent fires in increasing the dominance of the herbaceous layer in detriment the shrub layer.