Deposição de serapilheira e nutrientes em uma mata não minerada e em plantações de bracatinga (Mimosa scabrella) e de eucalipto (Eucalyptus saligna) em áreas de mineração de bauxita

Abstract

The nutrients elements N, P, K, Ca, and Mg were quantified in a semi-deciduos mountain forest, and in eucalyptus (Eucalyptus saligna) and “bracatinga” (Mimosa scaabrella) plantations in areas degraded by mining, close to Poços de Caldas- MG (21º47’13” S - 46º34’10” W).In the eucalyptus annual litterfall was 7,100 kg.ha-1 with 202.4 kg.ha-1 of N, 4.4 kg.ha-1 of P, 46.2 kg.ha-1 of K, 440.2 kg.ha-1 of Ca and 54.0 kg.ha-1 of Mg. In the semi-deciduos mountain forest the annual litterfall was 4,490 kg.ha-1 with 245.2 kg.ha-1 of N, 10.3 kg.ha-1 of P, 39.5 kg.ha-1 of K, 292.8 kg.ha-1 of Ca and 57.5 kg.ha-1 of Mg, whereas in the “bracatinga” the annual litterfall was 3,460 kg.ha-1 with 217.6 kg.ha-1 of N, 11.1 kg.ha-1 of P, 11.4 kg.ha-1 of K, 194.1 kg.ha-1 of Ca and 25.3 kg.ha-1 of Mg. Therefore, the total quantity of mineral nutrients returned to the soil by litter decomposition is done according to the following sequences: Ca>N>Mg>K>P (semideciduos mountain forest andeucalyptus plantation) and N>Ca>Mg>K>P (“bracatinga”). In the litter of bracatinga was detected the smallest quantity of K, Ca and Mg, while, the higher quantity of N and P was detected in eucalyptus. The litter decomposition coefficient was higher in the bracatinga and eucalyptus. The presence of P by coming from organic matter decomposition is bigger in bracatinga plantation, N and Mg in the semi-deciduos mountain forest, and K and Ca in eucalyptus plantations. The lowest rate of P was observed in eucalyptus.