The Re della Pietra is a 2 km2 experimental forested catchment located in the Tuscan Apennines, Central Italy. The climate is temperate Mediterranean with wet (October–May) and dry (June–September) periods. The average annual precipitation depth is 1300 mm. Average monthly temperatures vary from 2 °C in January to 20 °C in August, and the average annual temperature is 10.5 °C. Elevations range from 634 to 1320 m a.s.l., the average slope is 27.5°, and the stream channel is approximately 3 km long. The catchment geology consists of sandstones corresponding to the Late Oligocene – Early Miocene Macigno Formation. The soil is well drained and typically deeper than 50–80 cm. Sand content ranged between 57 and 76 %, and clay content between 4 and 11 %. Soil texture is sandy loam, according to the USDA (1999) classification. The catchment area is predominantly covered by forests (>95 %), dominated by beech trees (Fagus sylvatica), oaks (Quercus cerris), and conifers (Pseudotsuga menziesii and Pinus nigra).

The Re della Pietra experimental catchment serves as a vital outdoor laboratory for advancing hydrological, ecohydrological, and ecophysiological research in a Mediterranean mountain environment. Recent studies have demonstrated that preferential flow and streamflow generation are primarily influenced by soil moisture, bulk density, and rainfall patterns (Kaffas et al., 2025; Macchioli Grande et al., 2024). Hillslope topography and stand structure influence throughfall variability and beech tree water use, with upslope trees experiencing greater water stress compared to those in riparian areas (Verdone et al., 2025; Fabiani et al., 2024). Integrating hydrological and ecophysiological perspectives is crucial for understanding feedbacks between hydro-climatic forcings and tree water fluxes (Cocozza & Penna, 2022; Murgia et al., in preparation). Ongoing studies further explore the role of soil moisture in sap flow and topographic controls on tree drought responses (Verdone et al., submitted), highlighting Re della Pietra’s value for interdisciplinary ecohydrological research (Penna, 2025)

Cocozza, C., & Penna, D. (2022). Towards a more active dialogue between hydrologists and ecophysiologists for interdisciplinary studies in forest ecosystems. Science of The Total Environment, 807, 150877. https://doi.org/10.1016/j.scitotenv.2021.150877

Fabiani, G., Klaus, J., and Penna, D.: The influence of hillslope topography on beech water use: a comparative study in two different climates, Hydrol. Earth Syst. Sci., 28, 2683–2703, https://doi.org/10.5194/hess-28-2683-2024, 2024.

Kaffas, K., Murgia, I., Menapace, A., Macchioli Grande, M., Verdone, M., Dani, A., Manca di Villahermosa, F., Preti, F., Segura, C., Massari, C., Klaus, J., Borga, M., & Penna, D. (2025). Controls on preferential flow and its role on streamflow generation in a Mediterranean forested catchment. Journal of Hydrology, 660, 133469. https://doi.org/10.1016/j.jhydrol.2025.133469

Macchioli Grande, M., Kaffas, K., Verdone, M., Borga, M., Cocozza, C., Dani, A., Errico, A., Fabiani, G., Gourdol, L., Klaus, J., Manca di Villahermosa, F., Massari, C., Murgia, I., Pfister, L., Preti, F., Segura, C., Tailliez, C., Trucchi, P., Zuecco, G., . . .  Penna, D. (2024). Seasonal meteorological forcing controls runoff generation at multiple scales in a Mediterranean forested mountain catchment. Journal of Hydrology, 639, 131642. https://doi.org/10.1016/j.jhydrol.2024.131642

Penna, D. (2025). Climate and landscape drive catchment hydrological processes at the global scale. Nature Water, 3(4), 372-373. https://doi.org/10.1038/s44221-025-00411-0

Verdone, M., Van Meerveld, I., Massari, C., & Penna, D. (2025). Variability and temporal stability of throughfall along a hillslope. Journal of Hydrology, 647, 132294. https://doi.org/10.1016/j.jhydrol.2024.132294