Rainfall partitioning in young clonal plantations Eucalyptus species in a subtropical environment, and implications for water and forest management

Abstract

Different canopy characteristics of industrial eucalyptus may lead to differences in water evaporation and availability to plants. This study aims to understand rainfall partitioning in a young clonal plantation (age of 2–4.5 years) of three eucalyptus species by relating tree parameters: diameter at breast height, total height, and leaf area index. We measured rainfall, throughfall, stemflow and litter interception, along with the tree parameters. The eucalyptus trees had rainfall interception varying between 22 mm (for 178 mm of rainfall) and 42 mm (for 87 mm of te rainfall), throughfall between 106 mm (for 186 mm of rainfall) and 44 mm (for 74 mm of rainfall), and stemflow between 0.5 mm (for 92 mm of rainfall) and 1.4 mm (for 24 mm of rainfall). For the three species, rainfall interception varied between 12 and 48%, throughfall between 57 and 90%, and stemflow between 0.3 and 5.4%. The coefficient of determination between interception and rainfall was 0.76, indicating interception depends on other variables, possibly including antecedent rainfall, rainfall intensity, and seasonality. Interception decreased with a reduction in leaf area index caused by eucalyptus defoliation. The E. benthamii had 0.75 mm of throughfall per 1 mm of rainfall, whereas in E. dunnii and E. saligna, these ratios were 0.71 and 0.68, respectively. Stemflow in E. benthamii and E. dunii had a higher positive relationship with the diameter at breast height of the trees, whereas in E. saligna the highest relationship was with the rainfall. These results contribute to establishing management strategies, such as choosing suitable eucalyptus species to local climate, and to improve the synchronization of crop-demand versus soil-water-supply while maintaining streamflow to fulfill ecological and production needs.