NUTRIENT ACCUMULATION IN THE ABOVEGROUND BIOMASS, IN THE LITTER LAYER AND PHYLLODIES DECOMPOSITION OF Acacia mangium Willd.

Abstract

Nutrient concentrations and contents in the shoot (leaves, branches, bark and wood) in a five-years-old stand of Acacia mangium Willd. (mangium), decomposition rate of mangium phyllodies (modified leaves) and nutrient efficiency use were evaluated in a forest stand in Seropédica, Rio de Janeiro State, Brazil. The species presented a high nutrient use efficency and accumulated 135 t.ha-1 of above ground biomass, containing: 544.9 kg.ha-1 of N, 281.7 kg.ha-1 of Ca, 242.9 kg.ha-1 of K, 47 kg.ha-1 of Mg and 35.2 kg. ha-1 of P). There was an accumulation of 12.7 t.ha-1 of litter and this layer contained 251.0, 5.7, 14.6, 102.7 and 22.7 kg.ha-1, respectively, of N, P, K, Ca and Mg. The decomposition constant (k) estimated for the phyllodies decomposition was 0,00165 g.g-1.day-1 and the half-live was 421 days. The accumulation of litter on the ground may represent an advantage as nutrient supply for succeeding crops or disadvantage as fuel in areas subject to frequent fire.

Keywords

• florística
• pioneiras