Contribution of the soil seed bank to post-fire recovery of a heathland

The importance of a soil seed bank was evaluated through its role in the recovery of a burnt shrubland. The study was carried out in a heathland characterized by several ericaceous species. Part of the heathland was burnt in a wildfire on 7 April 1991, while the rest was not affected by the fire and used as a control. Soil samples were collected three days after the wildfire, in the absence of rain; 10 samples (20×25 cm width to a depth of 5 cm) were collected from the burnt area and 10 from the control. Samples were set out in a greenhouse where germinating seedlings were recorded, counted and identified for 17 months. Observations were also carried out twice in the field for 14 months after the wildfire by examining two permanent transects in the study area and recording all regenerating species. The results show a low correspondence between soil seed bank and aboveground vegetation: only 23% of the identified taxa appeared both in the bank and in the field observations. From these species 65% of them have dispersal types like autochory or barochory, that is they generally fall near the mother plant. In the identified species as a whole, therophytes and hemicryptophytes dominate in comparison with chamaephytes, phanerophytes and geophytes; this also applied to the herbaceous species in comparison with the woody ones. Potentially soil possesses an important seed bank, which contributes poorly to the vegetation recovery after fire.