This data set reports the characterization of fallen necromass as the volume and density of coarse woody debris (CWD), and standing necromass as the volume and density of standing dead trees. Measurements were made in undisturbed and logged forest areas of the Tapajos National Forest, and Cauaxi Forest, Para, Brazil, and Juruena Forest, Mato Grosso, Brazil from 2002-2004. Fallen and standing necromass were classified into one of five categories according to its state of decomposition. There are two comma-delimited ASCII data files with this data set: two files contain the sampling information, decomposition state, and DBH measurements. There are also two files provided as companion data files which provide sampling transect descriptions.