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Rethinking Stemflow: Distribution, Infiltration, and Isotopic Insights in Forests
Juan Andres Pinos from the University of Nevada, Las Vegas
In Person Location: ISB 221
Stemflow represents a spatially concentrated and chemically enriched flux of intercepted precipitation that delivers water and solutes to near‐stem soils. Conventional approaches neglect potential heterogeneity in stemflow redistribution aboveground and its subsurface infiltration pathways, introducing bias into forest water balance modeling. Furthermore, stemflow is almost always overlooked in isotope-based hydrological models, and consequently, its isotopic signature remains poorly characterized. Accounting for the stemflow isotopic signal may reduce uncertainty estimates of near-stem water sources and flow pathways. To address these gaps, we combined field experimentation with stable water isotope tracing to investigate (i) the circumferential distribution of stemflow along tree trunks, (ii) its preferential infiltration pathways, and (iii) isotopic modification during canopy interception and redistribution. Our results demonstrate that stemflow is non-uniformly distributed around the trunk, with patterns influenced by tree lean and canopy structure. Upon reaching the soil, stemflow preferentially infiltrates along coarse roots and macropores, extending both vertically and laterally within the soil matrix. Additionally, stemflow exhibits isotopic enrichment relative to open rainfall, reflecting canopy retention and evaporative fractionation during interception. These findings challenge assumptions of uniform stemflow distribution, refine mechanistic models of stemflow infiltration, and highlight isotopic modification. Together, they advance understanding of forest–water interactions and their implications for landscape hydrology.