Comparative analysis of productivity, transpiration and water use efficiency in three Eucalyptus species with different drought tolerance levels

The increasing concern about water usage by highly productive crops, such as those from the Eucalyptus genus, coupled with the quest for greater water use efficiency, has intensified due to the expansion of forest plantations into marginal areas in Brazil with lower water availability—a trend likely to be exacerbated by climate change. Understanding the morphological characteristics and key ecophysiological processes that regulate tree growth and water use is crucial for selecting and enhancing drought-tolerant species. This study aimed to assess the growth and productivity of Eucalyptus grandis (low drought tolerance), Eucalyptus urophylla (moderate drought tolerance), and Eucalyptus camaldulensis (high drought tolerance) and their relationship with transpiration and water use efficiency (WUE). We established experimental plots with these three species in Southeastern Brazil. Each species was planted in plots of 380 trees, spaced at 3m x 3m. A measurable area of 36 trees per species was used for non-destructive assessments, while the remaining rows were allocated for destructive sampling. We measured growth, above-ground biomass, transpiration, leaf area index (LAI), leaf water potential, effective precipitation, soil moisture, and calculated WUE. E. grandis and E. camaldulensis transpired more than E. urophylla during the assessment. E. grandis and E. urophylla presented the highest stand WUE for stem wood biomass production throughout the study period (0.94 and 0.63 kg mm -1 , respectively). In contrast, E. camaldulensis presented the lowest WUE (0.19 kg mm -1 ). This study underscores the potential role of E. urophylla in achieving high productivity with relatively lower water consumption.