Understanding the relationships between plant traits and ecosystem properties at large spatial scales is important for predicting how compositional change will affect carbon cycling in tropical forests. Here, we examine the relationships between species wood density, maximum height and wood production for 60 Amazonian forest plots. Firstly, we examine how community-level species traits vary across Amazonia. Average species maximum height and wood density are low in western, compared to eastern, Amazonia and are negatively correlated with aboveground wood productivity and soil fertility. Secondly, we compare biomass growth rates across functional groups defined on the basis of these two traits. In similar size classes, biomass growth rates vary little between trees that differ in wood density and maximum height. However, biomass growth rates are generally higher in western Amazonia across all functional groups. Thirdly, we ask whether the data on the abundance and average biomass growth rates of different functional groups is sufficient to predict the observed, regional-scale pattern of wood productivity. We find that the lower rate of wood production in eastern compared to western Amazonia cannot be estimated on the basis of this information. Overall, these results suggest that the correlations between community-level trait values and wood productivity in Amazonian forests are not causative: direct environmental control of biomass growth rates appears to be the most important driver of wood production at regional scales. This result contrasts with findings for forest biomass where variation in wood density, associated with variation in species composition, is an important driver of regional-scale patterns. Tropical forest wood productivity may therefore be less sensitive than biomass to compositional change that alters community-level averages of these plant traits.