Resumo

Background: Water availability is a key driver of Eucalyptus productivity in tropical environments, yet traditional climatic indices often fail to adequately capture hydrological variability under humid conditions. This study evaluated how water availability, interacting with soil and management factors, influences productivity and basic wood density across contrasting tropical environments. Data from commercial Eucalyptus plantations across São Paulo, Bahia, and Maranhão were analyzed using multivariate regression models integrating climatic indices and a novel water-availability proxy (Log₁₀(AWAI)).
Results: The models showed high predictive performance (adjusted R²> 99%), with the proposed proxy exhibiting greater explanatory power in São Paulo and Maranhão. Basic wood density emerged as an integrative trait linking growth and environmental conditions: under humid climates, higher density was associated with increased biomass accumulation, whereas under drier conditions it reflected conservative strategies related to hydraulic safety. Additionally, clone HGU-1 demonstrated high ecophysiological plasticity and productive stability across contrasting environments.
Conclusion: The proposed proxy improves the representation of water availability in tropical conditions and supports more accurate water zoning, genetic material selection, and management strategies. These findings highlight the role of basic wood density as a functional indicator of the growth–safety trade-off in Eucalyptus plantations.