Spatio-temporal variation in a seed bank of a semi-arid region in northeastern Brazil

This study aimed to evaluate variations in the seed bank within a 3-year temporal series in order to answer the following questions: 1) Does the seed bankʹs species richness and seed density differ among climatic seasons and between years? 2) Are there differences in the richness and density of seed banks between the litter and mineral soil? 3) Can the seed bankʹs species richness and seed density be explained by characteristics such as the previous yearʹs precipitation and soil depth (litter or mineral soil)? The samples were collected from litter and mineral soil (0–5 cm), in 210 sub-plots, during the dry and rainy seasons of each year (August 2005 through February 2008). Overall, 79 species were recorded. On average, 1 168, 304 and 302 seeds.m−2 were recorded in the seed bank during years I, II and III, respectively. This study showed that the Caatingaʹs seed bank is rich in herbaceous species, yet speciesʹ density and richness are low in the litter. Furthermore, about 43% of the variation in species richness and density was explained by soil depth (litter and mineral soil) and previous yearsʹ rainfall.