Summary
This study deals with the development of regression equations to predict fresh weight of young individuals of Cecropia sciadophylla Martius. a commonly encountered tree species in the Amazon basin, based on measurements of their basal diameter or height. Cecropia spp. could represent an important source of pulp or biomass since they are Important constituents of secondary succession habitats and thus are readily accessible. Unbranched individuals of C. sciadophylla between 0 and 10 meters tall were collected from two different habitats. The first was from open roadsides where 51 individuals were collected and the second was along a road cut through a tall forest where 47 individuals were collected. There was a high linear correlation between basal diameter and tree height in both habitats, r = 0,975 (P<0.01) in the open and r = 0,963 (P<0.01) in the forest. In both habitats a power function between basal diameter and total fresh weight had the highest coafficient of determination, r2 = 0.978 (P < 0.01) in the open and r2 = 0.994 (P < O.01) in the forest. Height against total fresh weight also had highly significant values for the coefficient of determination. The distribution of biomass between leaves and stem was different between habitats although total tree weight was similar. In the open habitat more biomass went into the stem while in the forest leaf weight increased in relation to stem weight. Therefore the use of C. sciadophylla as a biomass source would be more productive from open areas than forested ones. The derived regression equations were also used to estimate fresh weight of a larger branched individual. The equation between basal diameter and total fresh weight was within 2% of the actual value hile that for height versus total fresh weight was less than 50% of the actual value. Future studies must deal with estimation of the density of this species to determine the quantity of available biomass present.