Ecological differences were investigated for two co-existing pioneer species from the Cecropia family for variation of first branch height and canopy width across old field and old-growth forest habitats and within habitat variation between species. Forest enumeration data was collected, on all trees >5 cm DBH, from 4 study sites, each containing 9 old-growth forest and 4 old field plots, within the Los Cedros reserve, Ecuador. Cecropia species 1 was not locally more abundant but was found to be more spatially distributed at 32 of the 52 plots; Cecropia sp. 2 was only present at 7 of the 52 plots. Coefficients of variation and allometric relationships were investigated within species and between habitats. No significant variation was found for either species between habitats. For investigations of first branch height Cecropia species 1 was significantly lower than Cecropia sp. 2 in comparisons of actual first branch height (old-growth forest, p