EFFECT OF FUNCTIONAL STRATEGIES AND ABUNDANCE OF Acacia mangium Willd ON THE NUMBER OF NATIVE SPECIES IN A SECONDARY FOREST FRAGMENT IN SOUTHERN AMAPA, BRAZIL

Abstract

Acacia mangium Willd is a fast-growing exotic tree that, when inserted in a different environment, can present an invasive potential in secondary forests. This study aimed to analyze the effect of abundance and functional strategies of A. mangium Willd and edaphic factors on native species richness in a secondary forest fragment located behind the Instituto Federal do Amapá campus Laranjal do Jari, Amapá. For this, all tree individuals with diameter at breast height (DBH) ≥ 10 cm occurring in 10 plots of 200 m2 distributed in the fragment were identified. Soil samples were collected in the plots and sent for fertility and granulometry analysis. Three leaf functional attributes of individuals of A. mangium Willd occurring in the plots were measured: leaf area (LA), leaf thickness (LT) and specific leaf area (SLA). A total of 145 tree individuals and 14 species were sampled, with A. mangium Willd being the most abundant with 95 individuals. The relative abundance of A. mangium Willd was negatively related to native species richness in the fragment. The species also exhibited distinct leaf attributes and abundances according to the variation in soil acidity and fertility in the fragment, which influenced the number of native species. There is a need to develop monitoring and management of invasive exotic species such as A. mangium Willd in fragments of secondary forests, since the species is invasive and opportunistic, and can inhibit the regeneration of native species after local disturbances.