Comparison of the effect of winch-assisted timber harvesting systems and cable yarding on soil water retention and surface runoff in a temperate deciduous forest

• Surface runoff showed a pronounced increase on harvester-forwarder trails. • Cable yarding caused no surface runoff & overall smaller effects on soil hydrology. • Water retention curves shift from bimodal towards unimodal after compaction. • Warmer and wetter winters emphasize the need for careful harvesting practices. Timber harvesting, especially when involving heavy machinery, significantly affects forest soil properties, including soil water retention and surface runoff. This study investigates the impacts of different timber harvesting systems (tracked harvester and forwarder (H+), non-tracked harvester and forwarder with tracks on uphill axles (H-), and cable yarding (MC)) on surface runoff and soil hydraulic properties in a temperate hardwood forest. We conducted rainfall simulation experiments (50 m 2 irrigation plots) before and after timber harvesting at a beech-dominated ( Fagus sylvatica L.) site in the Vienna Woods, Austria, to measure changes in surface runoff. Additionally, soil samples were collected after irrigation experiments to assess bulk density, saturated hydraulic conductivity (Ksat), and water retention characteristics. Surface runoff increased substantially after timber harvesting on skid trails, with the highest runoff on H+ (final runoff coefficient 0.67). In contrast, no runoff was observed on MC and the untrafficked control. Logging-induced soil compaction reduced Ksat (> 2 magnitudes; H+ and H-) and increased bulk density (up to 49 %; H-), particularly for ground-based timber harvesting methods. Water retention curves revealed a loss of macroporosity, and a shift towards a unimodal pore size distribution at 5 cm depth in all harvesting treatments. For cable yarding this shift was absent at 15 cm depth. Our findings underscore the importance of selecting appropriate machinery and timber harvesting practices to minimize soil disturbance and its hydrological impacts, particularly as wetter winter conditions, affecting the typical hardwood logging period, become more common due to climate change.