Changes in root morphological traits, soil properties, and infiltration characteristics following the conversion of native forests to Carya cathayensis plantations in the Dabie Mountainuous Area, China

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} ), and native forest was chosen as control (CC _{0 year} ). The 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 were mainly affected by soil non-capillary porosity, while AIR was mainly influenced by 5-2 mm water stable aggregate fraction; (4) The Kostiakov model is found to be the most appropriate for characterizing soil infiltration characteristics in the study 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 Mountains area.