This study aimed to evaluate the content of organic carbon in plant parts (leaves, wood, twigs and bark) of forest species Acacia mearnsii De Wild, Eucalyptus grandis Hill and Mimosa scabrella Benth, under different spacing between trees (2.0 m x 1.0 m, 2.0 m x 1.5 m, 3.0x1.0 m and 3.0 m x 1.5 m), one year after planting. It was also aimed to verify if the conversion factor of 50% can be applied. To determine t...