PREDICTION OF EUCALYPTUS PRODUCTIVITY AND BASIC WOOD DENSITY USING A NOVEL WATER-AVAILABILITY-SENSITIVE PROXY

Abstract

Background: This study evaluated how water availability, in interaction with soil and management attributes, modulates volumetric and mass productivity and basic wood density in commercial Eucalyptus plantations distributed across São Paulo, Bahia, and Maranhão, encompassing six Köppen climate types. A total of 63 production units and 16 clones were analyzed, integrating classical climatic indices and a novel water-availability proxy. Volumetric productivity and basic wood density were standardized to seven years, and multivariate regression models were fitted considering basic wood density at seven years, altitude, soil texture, stand age, and spacing. Results: The models showed excellent performance (adjusted R² > 99%), with the proxy exhibiting greater explanatory power in São Paulo and Maranhão, whereas soil texture and spacing were more influential in Bahia. Basic wood density emerged as an integrative variable: under humid climates, increases in density favored biomass accumulation, while under dry climates they reflect conservative strategies associated with hydraulic safety. Clone HGU-1 stood out for its high ecophysiological plasticity and productive stability under contrasting environments. Conclusion: The results demonstrate that the proposed proxy is sensitive and effective for water zoning, genetic material selection, and management recommendations, and that basic wood density functions as a functional indicator of the efficiency–safety trade-off in tropical environments.