Rainfall partitioning of tree species in a seasonally dry forest in a semiarid region of Brazil

The rainfall distribution in seasonally dry tropical forests is fundamental to the water balance in several world regions. This study aimed to quantify rainfall partitioning by the Caatinga Biome, and its relationship with the rainfall characteristics and morphological characteristics of seven species. The study was conducted in the Brazilian semiarid region, from November 2017 to December 2020. Rainfall partitioning was measured to determine internal precipitation (Tf), stemflow (Sf) and interception (I), and to analyse the relationship with total rainfall, intensity and duration, and with tree characteristics: plant height; number of stems; diameter at breast height; and crown projection area. A total of 167 rainfall events were identified with Tf, Sf and I accounting for 83.1 %, 0.5 % and 16.4 % of the total rainfall. The amount of rainfall varied from 1 to 141 mm (mean of 12 mm). Duration ranged from 0.17 to 9.17 h (mean of 1.78 h), while rainfall intensity ranged from 1.2 to 27.6 mm h−1 (mean of 5.9 mm h−1). There were variances in rainfall partitioning between the species, with Aspidosperma pyrifolium showing the greatest I (21.0 %). Rainfall characteristics affected the Tf, Sf and I, more than the morphological characteristics of trees for some species. However, the results of regression analysis showed that Tf, Sf and I were most correlated with amount of rainfall (0.20 < R2 < 0.90; p < 0.001). The rainfall partitioning according to the predominant tree species should be considered in seasonally dry forests in the semiarid region of Brazil to improve water resource management.