CARBON STORAGE IN THE SOIL AND IN THE BIOMASS OF EUCALYPT PLANTATIONS

Eucalypt is the main commercial forest species in Brazil, but very little information is available in the literature on the amount of carbon stored in the soil and in the biomass of these forest stands. The main objective of this study was to estimate the amount of soil-stored carbon (SSC) of eucalypt plantations and determine soil and climate characteristics that influence SSC. The study was carried out in the Central-Eastern region of Minas Gerais State, Brazil, in five micro-regions (CO, RD, SB, SA, and VI) with varying soil and climatic conditions. Soil carbon was determined to a depth of 100 cm. Carbon in the forest floor was estimated by allometric equations. The carbon stored in the soil-plant system differed among micro-regions and soil classes. SSC ranged from 183.1 t ha(-1) in Red Latosol to 95.1 t ha(-1) in Inceptisol, and was negatively correlated to soil K, Ca2+, and Mg2+ content and density in the top soil layer. SSC was highest in the micro-region VI (141.2 t ha(-1), average value for all soil types) and lowest in RD (80.8 t ha(-1)). Considering the soil-plant ecosystem and the usual rotation age (84 months), the absolute SSC value was greatest in the micro-region SA (251.6 t ha(-1)) and lowest in RD (186.8 t ha(-1)). Regression equations showed that the clay and aluminum content and altitude and water stress explained most of the SSC variation.