Disturbance-intervention interactions on post-windthrow hillslope runoff and erosion processes in the Eastern Italian Alps

• Wind is a major disturbance agent in managed mountain forests of the European Alps. • Post-windthrow runoff and erosion dynamics through space and time are poorly known. • Plot-scale runoff and erosion under four forest recovery scenarios were assessed. • Legacy deadwood and time since disturbance moderated runoff and erosion responses. • Understanding upstream disturbance-recovery dynamics clarifies catchment responses. Extensively disturbed catchments undergo heterogeneous vegetation recovery trajectories due to complex disturbance-intervention interactions. Windstorms are one of the major disturbance agents in intensively managed mountain forests of the European Alps; however, little is known about how post-windthrow runoff and erosion processes change in time and space due to limited empirical studies covering multiple disturbances and interventions. Between vegetation periods 2021–2023, we monitored water and sediment fluxes from four 4.5-m-wide × 6.0-m-long plots in a headwater catchment of the Eastern Italian Alps, characterized by deadwood (salvaged/unsalvaged), time since windthrows (3–5 and 21–23 years), and regeneration (natural/artificial). Our monitoring data suggested unsalvaged deadwood has a minimal effect on storm runoff generation for 3–5 years after disturbances, whereas legacy deadwood seemed to offer better soil protection during erosive storms (maximum 5-min intensity > 40.2 mm h −1 ). Recently disturbed plots presented slightly yet significantly 1–2 % higher mean runoff coefficient after prolonged dry periods (30–45 days), implying the importance of disturbance history in better accounting for current hydrological responses. Saplings and trees artificially regenerated after windthrows marginally facilitated quicker runoff transfer, seemingly due to scale-dependent preferential flow pathways (microrelief and litter). Our continuous monitoring efforts underscore the critical need to recognize upstream vegetation recovery trajectories to advance our understanding of catchment-scale responses to major forest disturbances.