Quantifying spatiotemporal inconsistencies in runoff responses to forest logging in a subtropical watershed, China

Abstract

Global forest cover is undergoing significant transformations due to anthropogenic activities and natural disturbances, profoundly impacting hydrological processes. However, the inherent spatial heterogeneity within watersheds leads to varied hydrological responses across spatiotemporal scales, challenging comprehensive assessment of logging impacts at the watershed scale. Here, we developed multiple forest logging scenarios using the soil and water assessment tool (SWAT) model for the Le'an River watershed, a 5,837 ​km² subtropical watershed in China, to quantify the hydrological effects of forest logging across different spatiotemporal scales. Our results demonstrate that increasing forest logging ratios from 1.54% to 9.25% consistently enhanced ecohydrological sensitivity. However, sensitivity varied across spatiotemporal scales, with the rainy season (15.30%–15.81%) showing higher sensitivity than annual (11.56%–12.07%) and dry season (3.38%–5.57%) periods. Additionally, the ecohydrological sensitivity of logging varied significantly across the watershed, with midstream areas exhibiting the highest sensitivity (13.13%–13.25%), followed by downstream (11.87%–11.98%) and upstream regions (9.96%–10.05%). Furthermore, the whole watershed exhibited greater hydrological resilience to logging compared to upstream areas, with attenuated runoff changes due to scale effects. Scale effects were more pronounced during dry seasons ((−8.13 to −42.13) ​× ​10⁴ ​m³⋅month⁻¹) than in the rainy season ((−11.11 to −26.65) ​× ​10⁴ ​m³⋅month⁻¹). These findings advance understanding of logging impacts on hydrology across different spatiotemporal scales in subtropical regions, providing valuable insights for forest management under increasing anthropogenic activities and climate change.