Abstract
ABSTRACT Terra Firme dense forest occurs in 65% of the Amazonian region and is characterized by the high diversity of plant species and high occurrence of rare plant species. The objective of this work was to analyze the horizontal structure of 15 hectares of plots, randomly chosen from a set of 400 ha of permanent plots situated at the Experimental Site of Embrapa, Manaus, Amazonas State, Brazil. All individuals with DBH ≥ 10 cm were identified at the level of species in 2005. The VI values (Values of importance) were separated in classes of range with one (01) standard deviation and the individuals distributed according to DBH classes of 10 cm in amplitude. In total, 8771 individuals were identified, distributed into 264 species and 53 families. A larger number of individuals is concentrated in a few number of species, such as Protium hebetatum D.C. Daly, Eschweilera coriacea (DC.) S.A. Mori and Licania oblongifolia Standl, which sum up 21% of the total number of individuals and 12% of the VI. There is a high occurrence of rare species (36%). The families Sapotaceae, Lecythidaceae and Burseraceae together accounted for 39% of the total number of individuals. The diametric structure in an inverse-J shape shows that 80% of the individuals are concentrated in the DBH classes ranging from 10 to 30 cm. The results highlight the high occurrence of rare species and those with low density, and with distribution restricted to some plots, particularly those belonging to the lowest classes of VI, which deserve special attention in actions for biodiversity conservation and forest management.
Highlights
Brazil, a country with approximately one-third of the remaining rain forests in the world, is one of the most important repositories of global biodiversity (PAS 2008)
The objective of this work was to analyze the horizontal structure of 15 hectares of plots, randomly chosen from a set of 400 ha of permanent plots situated at the Experimental Site of Embrapa, Manaus, Amazonas State, Brazil
The results highlight the high occurrence of rare species and those with low density, and with distribution restricted to some plots, those belonging to the lowest classes of VI, which deserve special attention in actions for biodiversity conservation and forest management
Summary
A country with approximately one-third of the remaining rain forests in the world, is one of the most important repositories of global biodiversity (PAS 2008). The dynamics and structure of rain forests vary across the Amazon basin in an east-west gradient, following a pattern that matches variations in soil fertility (QUESADA et al, 2009). To describe these patterns of variation, using large data sets, such as those in the present study, is extremely important to enhance the understanding of the mechanisms that determine the distribution of species in nature (CORONADO et al, 2009). About 65% of the Amazon region is covered by a forest type named terra firme dense forest This plant typology is the most representative of the Amazon rainforest, mainly characterized by high richness and diversity of species with few individuals of each species and generally showing high dissimilarity floristic between adjacent plots (FERREIRA; PRANCE, 1998; LIMA FILHO et al, 2001; CONDÉ; TONINI, 2013)
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