Tree damage, allometric relationships, and above-ground net primary production in central Amazon forest

The loss of tree mass over time from damage can lead to underestimates in a bove-ground net primary productivity (ANPP) if not accounted for properly. Bias in the allometric relationship between trunk base diameter (D-b, at 1. 3 m height or above the buttresses) and mass can also lead to systematic er rors in ANPP estimates. We developed an unbiased model of the relationship between D-b and tree mass using data from 315 trees (greater than or equal to5 cm D-b) harvested in the central Amazon. This model was compared with o ther theoretical (n = 1) and empirical models (n = 4). The theoretical mode l, and one empirical model, made predictions that differed substantially fo rm our central Amazon model. The other three empirical models made predicti ons that were consistent with our model despite being developed in differen t tropical forests. Models differed mostly in predicting large tree mass. U sing permanent forest inventory plot data, our D-b versus tree mass model, and a bole volume model, we estimated that tree damage amounts to 0.9 Mg ha (-1) per year (dry mass) of litter production. This damage should be includ ed as a mass loss term when calculating ANPP. Incorporating fine litter dat a from published studies, we estimated that average ANPP for central Amazon plateau forests is at least 12.9 Mg ha(-1) per year (or 6.5 Mg C ha(-1) pe r year). Additional sources of error as described in the text can raise thi s estimate by as much as 4 Mg ha(-1) per year. We hypothesize that tree dam age in old-growth forests accounts for a significant portion of age related decline in productivity. (C) 2001 Elsevier Science B.V. All rights reserve d.