Response of soil seed bank to a prescribed burning in a subtropical pine-oak forest

Prescribed burning is a management instrument applied to reduce the risk of fire and favour revegetation. Our objective was to generate information about the dynamics of post-fire regeneration via the soil seed bank (SSB), for fire management in subtropical forests. Samples taken at soil depths of 0-3cm, 3-6 cm and 6-10 cm before and 5 h after a prescribed burn showed that the fire immediately increased the number of germinable seeds and species in a Mexican pine-oak forest. Most of the germinable seeds were from species in genera with small seeds exhibiting physical or physiological dormancy, and that are tolerant or require fire for germination. Fire increased the number of germinable seeds during the wet season and the number of species was greater in the area control at 0-6-cm soil depth after 1 year; so that the fire modified the SSB seasonal pattern. Species diversity was not altered and was dominated by perennial herbaceous and shrub species both before and 2 years after the fire. Although fire completely eliminated the aboveground biomass of the understorey vegetation, the SSB can promote regeneration and persistence of understorey vegetation following a prescribed surface fire of low severity for the ecosystem studied.