Differences in rainfall interception among Eucalyptus genotypes

Key message: Hydrological indicators such as rainfall interception of Eucalyptus genotypes are essential to guarantee the water sustainability of forest plantations under climate change scenarios. Abstract: Rainfall interception is a critical component of water balance in Eucalyptus plantations and may provide better water sustainability by reducing potential adverse effects under drought scenarios. This study evaluated rainfall interception of Eucalyptus globulus and E. nitens x globulus (high and low yield), E. nitens, E. badjensis, E. smithii, and E. camaldulensis x globulus. Rainfall, stemflow, throughfall, and interception (calculated as rainfall-stemflow-throughfall) were measured for 2 years (2020–2022) and correlated with plantation characteristics [diameter at breast height, total height, stem growth, and leaf area index (LAI)]. Our results showed an average rainfall of 1063.6 mm year⁻¹; only stemflow did not show differences among genotypes with an average value of 193.4 mm year⁻¹ (18.2% of annual rain). In contrast, throughfall and interception presented significant differences among genotypes, and both parameters showed a strong relationship with LAI. Therefore, three independent groups were obtained: E. badjensis and E. smithii showed the highest LAI (average 5.7 m² m⁻²) with 517.0 mm year⁻¹ of average interception and 427.6 mm year⁻¹ of average throughfall (48.6% and 40.2% respectively). For E. globulus (low-yield), E. nitens x globulus (low-yield), and E. nitens, that showed the lowest LAI (average 3.3 m² m⁻²), average throughfall reached 730.8 mm year⁻¹ (68.7%), and average interception reached 197.3 mm year⁻¹ (18.5%). Finally, E. globulus (high-yield), E. nitens x globulus (high-yield), and E. camaldulensis x globulus with an average LAI of 4.5 m² m⁻², average interception reached 345.2 mm year⁻¹ (32.5%), and average throughfall reached 602.7 mm year⁻¹ (56.7%). Our results suggest that understanding differences between taxas/genotypes may contribute to developing hydrological indicators that may improve estimates of plantation water sustainability under water scarcity climate change scenarios.