THE INFLUENCE OF FIRE ON THE SOIL SEED BANK IN SEMIDECIDUOUS FOREST

This study was carried out in a fragment called "Reserva da Biologia", which belongs to the Universidade Federal de Viçosa, in Minas Gerais State, Brazil (20°35'-28°50'S e 42°45'-43°00'W), where 10 plots of 5 x 5 m plots, 1m away from each other, were set up. A controlled burning was performed on the plots, following the wind-driven fire technique, according to the slope orientation. The objective was to characterize the soil seed of the tree community before and after fire, in order to verify the effects of such discontinuance on both population density and floristic composition. In the centre of each plot, one 40 x 25 cm soil sampling was collected, from the leaf litter downward 5cm deep. One day after the soil sampling the plots underwent controlled burning. New soil samplings were done immediately after burning, following the previous methodology. It was counted 528 and 429 seedlings emerging from the soil seed bank before and after the fire, respectively. Such plants were of 23 species and 14 botanical families, from which Melastomataceae, Asteraceae and Urticaceae stood out. There was no meaningful reduction in the species richness or in the density of individuals of the populations between both samplings. The floristic similarity was 34 %. Miconia cinnamomifolia and Leandra purpurascens were the most frequent/abundant species. Pioneer species stood out making up 44 and 40 % of the species found in the area before and after fire, respectively. Este estudo foi realizado no fragmento "Reserva da Biologia", situado na Universidade Federal de Viçosa, Minas Gerais, (20°35'-28°50'S e 42°45'-43°00'W) onde foram instaladas 10 parcelas de 5 x 5 m interdistantes em 1 m. Foi realizada uma queima controlada nas parcelas instaladas, utilizando a técnica do fogo a favor do vento, obedecendo ao sentido do aclive. O objetivo foi caracterizar o banco de sementes do solo antes e depois do fogo, para verificar os efeitos desse distúrbio na densidade das populações e na composição florística da comunidade vegetal. No centro de cada parcela foi coletada uma amostra de solo de 40 x 25 cm, a partir da superfície da serapilheira até 5 cm de profundidade. Um dia após a coleta das amostras de solos as parcelas foram submetidas à queima controlada. Imediatamente após a queima foram realizadas novas coletas de solo seguindo a mesma metodologia adotada anteriormente. Foram obtidas 528 e 429 sementes germinadas das amostras do banco de sementes do solo antes e após o fogo, respec