1,1,1,2,3,1,4,5,6,1- 1Research Institute for Geo-hydrological Protection, CNR, Perugia, Italy (silvia.barbetta@cnr.it, marco.dionigi@cnr.it, paolo.filippucci@cnr.it, marco.donnini@cnr.it, christian.massari@cnr.it)
- 2Research Institute for Geo-hydrological Protection, CNR, Rende (CS), Italy (domenico.desantis@cnr.it)
- 3School of Agriculture, Department of Agriculture, Food, Environment and Forestry University of Florence, Florence, Italy (matteo.verdone@unifi.it, daniele.penna@unifi.it)
- 4Forest Engineering Resources and Management Department, Oregon State University, Corvallis, USA
- 5Hydro-Climate Extremes Lab (H-CEL), Faculty of Bioscience Engineering, Ghent University, Belgium (diego.miralles@ugent.be)
- 6Hydrological Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA (thomas.r.holmes@nasa.gov )
Interception by forest canopies constitutes an important control on ecosystem water fluxes, with direct effects on soil moisture and water availability. In Mediterranean environments, high variability in precipitation across space and time complicates the estimation of interception and net precipitation. Field-based observations across contrasting forest canopies are therefore required to disentangle species-specific interception processes.
Precipitation partitioning within the forest canopy was analyzed using throughfall and stemflow observations in Quercus robur (oak) and Fagus sylvatica (European beech) stands over nearly three years in a 44 km² mountainous catchment in central Italy. Four plots were monitored during more than 200 precipitation events, capturing seasonal and species-specific variability.
Observed interception losses differed between species at closely located plots under comparable rainfall conditions, reflecting the combined effects of canopy structure and local meteorological conditions. Relative interception, defined as the fraction of gross precipitation evaporated before reaching the forest floor, averaged about 39% for oak and 31% for beech during moderate rainfall events. Although beech stands exhibited higher leaf area index (LAI) and canopy cover, oak consistently showed greater interception during both the growing (42% vs. 33%) and dormant (33% vs. 26%) seasons, highlighting that canopy architecture, rather than LAI alone, governs interception dynamics.
We tested a LAI-based Gash model against observed interception loss. The model underestimated the flux, indicating that simplified descriptors, such as LAI, do not adequately represent species-specific canopy architecture. This suggests that accurate representation of canopy traits, including branching patterns, leaf distribution, and canopy roughness, is essential for reliable predictions of intercepted precipitation, particularly in heterogeneous Mediterranean forests.
Overall, this study demonstrates that interception in broadleaf Mediterranean forests is influenced by a complex interaction between canopy structure and local environmental conditions. Incorporating these factors into interception models is essential to resolve precipitation partitioning and to evaluate ecohydrological responses to climate variability and forest management. The findings further highlight the relevance of species-specific field data to improve model parameterizations and hydrological predictions in ungauged forest ecosystems with contrasting canopy structures.
Keywords: canopy interception, precipitation partitioning, Mediterranean forest, throughfall, stemflow, forest canopy structure, interception modelling.
How to cite: Barbetta, S., Dionigi, M., Filippucci, P., De Santis, D., Penna, D., Verdone, M., Donnini, M., Miralles, D. G., Holmes, T., and Massari, C.: Contrasting Forest Structure Shapes Rainfall Interception in a Mediterranean Mountain Catchment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5141, https://doi.org/10.5194/egusphere-egu26-5141, 2026.
