Biomass and length of fine roots in Acacia mearnsii De Wild. stands established in a degraded area by coal mining

Abstract

The coal mining in open pit mining system cause great environmental degradation, mainly of the soil. The revegetação with arboreal species is the best form of recovering these areas. Among the potential species for the degraded areas recovery in the Brazil south, Acacia mearnsii stands out, for fast growth and symbiotic association capacity. The objective of present work was to estimate the biomass and the length of fine roots (≤ 2 mm of diameter) in different soil depths in a four years old Acacia mearnsii stands with 4 m x 1.5 spaced, established in a degraded area by coal mining. The study was carried out in Butiá (RS), in the Copelmi Mineração Ltda company. Four monoliths of 25 cm x 25 cm x 60 cm were sampled and divided into six geometric sections at depths 0-10, 10-20, 20-30, 30-40, 40-50, 50-60 cm and in these same depths soil samples were collected for chemical and density analysis. Roots were separated from the soil by using a set of two sieves (mesh 2 mm and 1 mm) and water jets. The intersection method was used to determine root length. Fine root total biomass and length found for Acacia mearnsii were 6,924 kg ha^-1 and 433,441 km ha^-1, standing out that 86.78% and 86.59%, respectively, were concentrated in the first 20 cm of soil depth.