Banco de sementes de áreas alteradas da região bragantina

Abstract

The forest of the Bragantina region in northeastern Pará has suffered slashing and burning for a century, but it is definitely not extinguished by deforestation. Certain species regrow from roots that survive the agricultural cycle and/or regenerate from seeds that are dispersed or stored in the soil. The objective of this work was to evaluate the density and floristic composition of the seed bank of secondary forests (capoeiras) of 3, 6 and 10 year old "roça" and 4-5 year old "pimental" capoeira in the municipality of São Francisco do Pará. Soil samples, measuring 20 x 20 cm and 0-5 cm deep, were collected from the stands and immediately packed in plastic bags, labeled and taken to the EMBRAPA greenhouse, where they were distributed in 25 x 40 cm trays, containing vermiculite as substrate. The first 15 days of evaluation showed an expressive number of germinations in the "pimental". After 63 days of evaluation, the pimental showed 48.2% of the total of 9,106 germinations recorded in all trays. The 3 year-old stands had 7.6% of germinations, the 6 year-old stands had 26.2%, and the 10 year-old stands had 18%. Data on the floristic composition of these seed banks will be presented in the final report. The understanding of the dynamics of the soil seed bank is an important practice for agriculture, forestry and conservation, serving to better use this mechanism as a form of regeneration in sustainable management and forest recovery.