Soil water infiltration is an important hydrological process influencing mountain ecosystems’ runoff and soil loss. Our study evaluates soil water infiltration characteristics and the underlying mechanisms under Carya cathayensis plantations with different planting years: 6 (CC 6 years), 20 (CC 20 years), and 50 (CC 50 years). Native forest was chosen as control (CC 0 year). Philip, Kostiakov, Kostiakov-lewis, and Horton models were selected to evaluate their applicability under different planting years of Carya cathayensis plantations. The results showed that: (1) Converting native forests to Carya cathayensis plantations significantly decreased soil water infiltration rates, with average infiltration rate ( AIR), initial infiltration rate ( IIR), and stable infiltration rate ( SIR) decreasing by 33.11% ~ 70.98%, 31.23% ~ 64.11%, and 40.13% ~ 75.01%, respectively；(2) Soil water infiltration rates were improved with planting years, with the highest value shown under CC 50 years；(3) The correlation and path analysis indicated that IIR and SIR was mainly affected by soil non-capillary porosity, while AIR was mainly influenced by 5-2 mm water stable aggregate fraction; (4) Kostiakov model is most suitable for modeling soil infiltration characteristics in the studied area. These findings shed insight into soil water infiltration processes and regulating factors for preventing and controlling soil erosion and restoring soil health in land use change, particularly forest cover conversion in the Dabie Mountain area.

Soil infiltration is a hydrological process dramatically affected by land use/cover changes. Taking the miscellaneous woody forest (MWF), a natural vegetation cover in the Dabie mountainous area, China, as the reference (control), this study aimed to evaluate the effect of litter, root traits, and soil properties on soil infiltrability and quantify the characteristics of soil infiltration processes of four intensively-managed sloping economic forests, including Castanea Mollissima forest (CMF), Castanea Mollissima-tea inter-planting forest (CMTF), Camellia Oleifera forest (COF), and Camellia Oleifera-tea inter-planting forest (COTF). The results showed that significant differences in soil water infiltration under different land use and management types (p < 0.05). Soil initial infiltration rate (IIR), average infiltration (AIR) and steady infiltration rate (SIR) decreased 39.63%-60.88%, 46.11%-67.39% and 49.88%-72.8%, respectively after the native forests were developed to economic forests, following the order: MWF > CMTF > COTF > CMF > COTF, but no significant difference was found between CMTF and COTF (p > 0.05). Soil water infiltration characteristics measured by IIR, AIR, and SIR were positively correlated to litter coverage, litter thickness, the maximum water-holding capacity of the litter, effective water-retention capacity, maximum water-retention capacity, root traits, capillary porosity, non-capillary porosity, total porosity, soil organic matter, and clay and silt content (p < 0.05), but negatively correlated with the bulk density, and sand and gravel content (p < 0.05). Variation partitioning analysis showed that soil water infiltration was more susceptible to soil properties than litter characteristics or root traits. The redundancy analysis explained 99.97 % of the variation to explore the relationship between litter characteristics, root traits, soil properties, and soil water infiltration characteristics, and the clay content is the main factor affecting soil water infiltration. The structural equation model suggested that land use and management indirectly affect soil infiltrability by modulating soil properties through affecting litter and root traits, with clay content having a higher contribution.