Abstract
The process of rainfall partitioning is usually addressed by three components: rainfall interception, throughfall and stemflow. The occurrence and proportion of stemflow depends on many complexly interconnected factors. To contribute to the interpretation of these interdependencies, the influence of rainfall event characteristics and phenoseasons on stemflow development was analyzed with a new approach. In this study we have focused on the development of stemflow during 156 rainfall events with complete time series records for a single birch tree (Betula pendula Roth.) at a study plot in the city of Ljubljana, Slovenia. For each one of the selected events, diagrams of rainfall and stemflow development during the event were prepared and grouped according to their visual similarities using hierarchical clustering. Additionally, significant meteorological characteristics were determined for each group of events. Four characteristic types of stemflow response were identified and connected to the corresponding event characteristics. Events showing negligible stemflow response to rainfall increase were characterized with rainfall amounts lower than 5 mm, high rainfall intensities, and occurrence in the leafed phenophase. A slow stemflow increase, independent of the increase of the rainfall volume in the open, was recognized for rainfall events delivering less than 20 mm of rainfall during a 5-h duration on average. The majority of these events were observed in the leafed phenophase, corresponding to higher air temperature and vapor pressure deficit. The occurrence of stemflow events, whose development followed the increase of the rainfall amount, was not dependent on the phenophase. However, during these events the average air temperature and vapor pressure deficit were lower, the rainfall amount was larger and the rainfall duration longer in comparison to the events showing independent increase with rainfall. The fourth type of response of stemflow was defined by a strong stemflow response in connection to large rainfall amounts and the longest rainfall duration, as observed for events in the leafless period. The four characteristic types of stemflow response provide additional information on the possible proportion of the rainfall reaching the ground as stemflow.
Highlights
Trees are an important part of vegetation in our environment, contributing to air quality, biodiversity, energy conservation, atmospheric CO2 reduction, aesthetics and quality of living environment (McPherson et al, 2005; Zabret and Šraj, 2019)
The average air temperature was equal to 12.4◦C (± 5.3◦C) and the average vapor pressure deficit was equal to 0.17 kPa (± 0.16 kPa) per event
A new approach was applied, namely the hierarchical clustering based on the graphical presentation of the rainfall and stemflow development during the event
Summary
Trees are an important part of vegetation in our environment, contributing to air quality, biodiversity, energy conservation, atmospheric CO2 reduction, aesthetics and quality of living environment (McPherson et al, 2005; Zabret and Šraj, 2019). Interception is the precipitation amount that is retained on leaves and branches, eventually evaporating to the atmosphere and not reaching the ground. Throughfall is the portion of the precipitation reaching the ground underneath the tree due to dripping from the leaves or falling through the openings in the canopy, while stemflow describes the flow of the precipitation down the tree branches and stem. In comparison to the amount and proportions of throughfall to gross rainfall, stemflow values are minor (Šraj et al, 2008; Staelens et al, 2008; Muzyło et al, 2012; Swaffer et al, 2014; Zabret et al, 2018; Sadeghi et al, 2020)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
