Abstract:The slash-and-burn agriculture practiced across tropical dry regions results in the elimination of native vegetation. Upon fi eld abandonment, the seed bank becomes a potentially important mechanism of natural regeneration at early successional stages. Soil properties and climate seasonality may affect seed bank characteristics, thus we analyzed the effects of these two factors on seed bank density and composition in agricultural fi elds of a seasonally dry tropical region of southern Mexico. Soil cores were collected for the rainy and the dry seasons in order to assess changes occurring in the seed bank from the time of harvest to the moment when succession could potentially start (the next rainy season). The 12 studied fi elds comprised three different soil types recognized by local inhabitants: sandy and stony, silty, and clayey soils, locally known as cascajo, black soil, and red soil, respectively. At each fi eld 20 soil cores (8 cm diameter, 4.5 cm depth) were collected and mixed to form four pooled samples, which were placed in a greenhouse to induce germination. A total of 4,422 seedlings (2,291 seeds m -2 ) representing 40 species were recorded. The most abundant species were, in decreasing order, Melanthera nivea, Rhynchelytrum repens, Waltheria indica, Amaranthus scariosus, Digitaria bicornis, and Cenchrus pilosus. Herbs were the prevailing growth form (> 80% of total richness). No clear pattern was observed in the seed bank related to soil type; however, seed bank characteristics tended to be associated with the time of use of the agricultural fi elds, a variable that was not controlled in the study. Seed bank species richness was signifi cantly larger in the dry season, and although seed density showed a similar trend, it was not signifi cant. The studied seed banks contain no elements of the regional primary tropical dry forest, which suggests that seed banks in deforested areas cannot guarantee their maintenance beyond forested areas. Key words: seed bank seasonal variation, seed germination, soil heterogeneity, tropical forest regeneration, weed ecology.Resumen: La agricultura de roza, tumba y quema practicada en regiones tropicales secas provoca la eliminación de la vegetación original. Cuando los campos agrícolas son abandonados, el banco de semillas puede ser un mecanismo importante de regeneración natural en etapas tempranas. Las propiedades del suelo y la estacionalidad climática pueden afectar las características del banco de semillas. En este estudio analizamos los efectos de estos dos factores sobre la densidad y la composición del banco de semillas de suelos agrícolas de una región de bosque tropical estacionalmente seco del sur de México. Se obtuvieron núcleos de suelo de la temporada de lluvias y de la seca para evaluar los cambios en el banco de semillas desde la cosecha hasta el momento en el que la sucesión podría comenzar (la siguiente temporada lluviosa). Los 12 sitios de estudio abarcaron tres tipos diferentes de suelos reconocidos por los habitantes locales: arenosos y ...