Biometric relationships for non-destructive above ground biomass estimations in young plantations of Acacia salicina Lindl. and Eucalyptus occidentalis Endl.

Above ground oven dried biomass (BM) of individual trees in young stands of Acacia salicina Lindl. and Eucalyptus occidentalis Endl. were correlated linearly and logarithmically to the square of the basal diameter at 0.2 m (DB) and to the latter multiplied by the height of the tree. Number of main stems at basal height per tree were included as well. DB measurements in young Eucalypt stands provided better BM estimates than the commonly used diameter at breast height (1.3 m) (DBH). The following biometric relationships, after cross-validation against an independent data set, showed the best fit: BM=0.1282*Σ (DB²) and BM=0.1700*Σ (DB²) for A. salicina and E. occidentalis, respectively, with Σ (DB²) ranging from 0-400 cm² and BM in kg tree^-1. For acceptable relative errors in biomass estimations Σ (DB²) should be larger than 100 cm². Foliage to wood ratios at Σ (DB²)<100 cm² for both tree species generally exceeded 1, but rapidly leveled off at 0.81±0.28 and 0.92±0.19 for the Acacia and Eucalypt spp., respectively, at higher Σ (DB²) values.