SEED BANK BUILDUP IN SMALL DISTURBANCES IN A MEDITERRANEAN PASTURE - THE CONTRIBUTION OF ENDOZOOCHOROUS DISPERSAL BY RABBITS

The importance of endozoochorous dispersal in seed bank build-up is an alyzed in artificial 40 x 40 cm disturbances in a Mediterranean pastur e. The top 10 cm of soil in the disturbances was replaced by sterile s oil, and the excrement laid in half of them was removed fortnightly. T he seed banks of the disturbances subjected to the two treatments was quantified by germination of soil samples (n = 44) gathered at the sta rt of the following growth season. Rabbit droppings were collected for tnightly to quantify their seed content and the pasture seed productio n was estimated. Seed bank regeneration takes place early in the distu rbances. The main source of qualitative variation in seed banks is the ir position on the slope, while endozoochory lacks a characteristic qu alitative effect. However, endozoochorous dispersal is responsible for a significant increase in the number of germinable seeds, the richnes s and diversity of the seed bank samples with respect to those lacking it. The importance of endozoochorous dispersal by rabbits in grasslan d dynamics is suggested to be its effect on the colonization of small disturbances, where species dispersed with dung are found to be favour ed. This aids the maintenance of grazing-tolerant communities.