Unveiling the Role of Acrocomia aculeata Palms in Savanna Hydrology: Insights from Bark Morphology and Stemflow Dynamics

In this study, we investigated stemflow in Acrocomia aculeata trees in an Amapá savanna, in an Amapá savanna, focusing on the influence of structural traits on stemflow volumes. Diameter at breast height, crown area and height of trees were determined. Bark hydrophobicity and texture were also investigated. During the sampling period, total precipitation was 1,744.3 mm, with stemflow accounting for 0.71% of this total. This value is lower than previously reported, highlighting the variability of stemflow across different environments and study conditions. We found significant diversity in stemflow volumes among the studied individuals, which were categorized into three classes: high (more than 0.18mm), medium (between 0.10-0.18mm) and low (less than 0.10mm). . Our analysis revealed a strong correlation between bark contact angle and stemflow volumes, indicating that surfaces with higher hydrophobicity favor greater water flow to the soil. This emphasizes the relevance of bark physical properties in regulating stemflow. Principal component analysis indicated that the combination of stemflow and bark contact angle, along with characteristics such as crown geometry and height, explains most of the variability in stemflow volumes. However, other morphological characteristics such as diameter at breast height and projected crown area showed no significant correlation with stemflow, suggesting bark morphology might play a more determining role in stemflow than initially thought. Significant structural differences in bark surfaces were observed through scanning electron microscopy and optical microscopy, indicating that bark texture, including the presence or absence of grooves and furrows, influences stemflow capacity. This study enhances our understanding of the complex interactions between palm tree morphological and dendrometric characteristics and stemflow, highlighting the importance of considering bark hydrophobicity and structural properties in forest hydrology studies. The results suggest the need to explore bark characteristics beyond its morphology to understand stemflow dynamics in savanna ecosystems.