The objective of this research was to identify and assess community structure and diversity of herbaceous invasive species present in the soil seed bank in subsistence cropping areas in the municipalities of Bacabal, Lago Verde, São Luís Gonzaga and Vitorino Freire, located in parts of the Ombrophilous Open Forest with Babassu, in Maranhão State, northeastern Brazil. Fifteen 50 m2 plots were laid out in each municipality from which 90 soil samples were taken with an open metal template of 25 x 16 x 3 cm and placed in trays in the greenhouse. Data assessed were individual and species number; relative values of density, frequency, abundance and the importance value of each species. Data were submitted to the Analysis of Variance and to the Principal Coordinate Analysis. The diversity was computed by the Shannon’s Diversity Index. The highest floristic richness in the seed bank was observed in Bacabal with 50 species from 34 genera and 17 families, which also had the highest number of individuals, with 11.541. The highest floristic similarity was observed between Lago Verde and Vitorino Freire. The dominant species based in the importance value were: Ludwigia octovalvis (VI = 34,8%) in Bacabal, Scleria lithosperma (VI = 37.0%) in Lago Verde and Boerhavia erecta (VI = 40.4%), in São Luís Gonzaga and (VI = 57.0%) in Vitorino Freire. Diversity reached the highest value in Bacabal with H’= 2.66 nats ind-1. The results may be used to forecast invasive species infestations in municipalities of the studied region.
Pioneer species; Invasive species; Floristic
