Variação espacial e sazonal do banco de sementes do solo em uma área de caatinga, Serra Talhada,PE

Abstract

This study aimed to contribute to the understanding of the seed bank seasonal and spatial variation in two different topographic situations (upper and lower slopes), two types of erosion (rills and interrills) and two periods (dry and rainy seasons) in an area of caatinga located in Serra Talhada municipality, state of Pernambuco (PE). Sixty soil samples were collected and 60 erosion pins were installed near each soil collection spot, in the intention of evaluating the removal level and deposition of the soil, in the two climatic seasons and in the rills and interrills. The bank’s density was evaluated by the emerged plantules method. About 79% of the seeds germinated in the bank are herbaceous annual. The density of germinated viable seeds was greater during the rainy (5.727,3 seeds/m2) that in the dry season (1.369,0 seeds/m2), and the upper than in the lower slope in both period. With relationship to the erosion types, there was just at that significant difference rainy season, where the interrills presented greater number of seeds and larger removal of the soil. The seasonal variation of the bank is registered in other arid andsemi-arid areas of the world that also point prevalence of herbaceous of short life cycle and larger density in the rainy period. Possible explanations for these patterns point the need of more studies on caatinga erosion, once the results of the removal-deposition processes differed of the told in the literature.