Floristic composition dynamics of the understory in a logged tropical forest, municipality of Moju, State of Para, Brazil

Abstract

The understory vegetation of tropical forests has been little studied despite its importance for the sylviculture of forests under management. The floristic composition dynamics of an understory influenced by gaps caused by reduced impact logging was analyzed for 12 years in a solid ground rain forest in Eastern Amazonia, municipality of Moju, State of Para, Brazil. Angiosperm individuals from 10 cm height to 5 cm DBH were surveyed in a 468 m² sample area in six occasions. Data were analyzed considering vegetation life-forms (trees, shrubs, lianas, herbs and palms). A total of 17,264 plants from 73 families, 180 genera and 256 species were recorded in the study area. An increase in the amount of species and individuals was observed until three years after logging, but it decreased in the following years. Trees were the most representative life-forms followed by lianas and herbs. There have been great changes in the composition of the less abundant species during the study period. The vegetation in the area was in a successional process, evolving from the gap to the growth phase. The dynamics of understory is higher in the early successional phases, with higher light intensity, decreasing according to the canopy closing process, which enables the establishment of the individuals that will compose the forest community for the future harvests. The maintenance of the area without additional disturbances after wood harvesting is fundamental to ensure the floristic and structural recovery of the ecosystem.