Abundância e diversidade de artrópodes edáficos em agricultura de corte e queima na Amazônia Oriental

Abstract

Family farming is characterized by subsistence and productive diversity, basically using the cutting cultivation and burning for the implementation of cultures. The fire usually causes changes in environmental conditions, the amount of biomass in a diversity of species and these ecosystems. The community of arthropods depends on various structural elements that can be impacted by the fire, including the amount of crop residues, abundance and composition of litter and soil moisture. In this sense, the aim of this study was to analyze the abundance and diversity of edaphic arthropods in cutting cultivation and burning in family farming property in the eastern Amazon. The study was conducted in agricultural establishment near the city of Marabá, Pará, from October 2012 to February 2013, in a Quartzipsamment with predominantly flat topography and vegetation of tropical rain forest. Arthropods of soil fauna were collected using pitfall traps of the trap type in five monthly samples, and installed four traps in line in the center of the growing area, four in the transition area (border) and another four in the center of secondary forest. The arthropod were taken to the laboratory of the Faculty of Agrarian Sciences of the Federal University of South and Southeast of Pará (Unifesspa), which were accounted for by the definition of abundance (number of morphospecies) and further classified into taxonomic groups. The average abundance were compared by T-test at 5% probability, using the statistical program ASSISTAT version 7.7 beta. The diversity was calculated using the Shannon diversity index (H), using the statistical program PAST version 3.06. 5,985 specimens were sampled, and the Coleoptera groups, Hymenoptera and Orthoptera the most abundant respectively, together accounted for 89.56% of all captured arthropods. The abundance of arthropods in cutting farming area and burning, decreased after the fire, but showed gradual increase two months after firing. The highest abundance was found in the transition area, followed by cultivation area and less in the forest, although not presenting significant difference between the agro-ecosystem. Diversity decreased afterburner and had not gradually increase until the end of the study. The greatest diversity was found in the area of cultivation, followed by forest area and lowest in transition.