Chuva de sementes em uma floresta de galeria no Parque do Bacaba, em Nova Xavantina, Mato Grosso, Brasil

摘要

The study was carried out in the gallery forest of the Bacaba stream, Municipal Bacaba Park (14o43'12.2S e 52o21'36.7"W) in Nova Xavantina, Mato Grosso state, Brazil. Seed rain was studied and compared among three forest sections (upper, middle and lower), 200 m away from each other, running downstream and differing in slope. Twenty circular seed-traps (0.3 m2) were randomically distributed at each forest section and monitored from June 2007 to May 2008. Seeds were dried until constant weight, and classified in two categories, based on the presence of flight structures (V) and the absence of these structures (NV). Number of morpho-species, seeds and biomass were compared at the forest sections through the dry and rainy periods. It was collected 20,965 seeds over 24 fortnights, being 777 seeds type V and 20,188 seeds type NV. In the upper section, 52 morpho-species of seeds were recorded in the middle 55 and in the lower 49. The morpho-species diversity of seeds was lower than the diversity of the woody species in the same area. Regarding the seasonal pattern for seed rain, for V (number, morpho-species and biomass) and for NV seeds (biomass) as well, the control of visitors in the Bacaba Park especially in the dispersion peak of seeds at the end of dry period and the beginning of the rains (September-December) is recommended. Tour of minimum impact may benefit the establishment of seeds and seedlings and ensure sustainability of the forest.