Effects of different vegetation restoration types on soil infiltration characteristics in severely eroded subtropical regions of South China

Abstract

Vegetation restoration could cause variations in soil and near-surface properties, altering soil structure directly or indirectly and consequently affecting soil infiltration characteristics. This study is aimed at exploring the variation of soil physicochemical properties and infiltration characteristics under five vegetation restoration types (including restored forest, restored orchard, restored scrubland, restored grassland, and unrestored eroded land, which are referred to as RF, RO, RS, RG, and EL, respectively) and the main factors affecting infiltration characteristics. The EL was taken as the control group. Five hydraulic heads (0, −3, −6, −9, and −12 cm) were set to continuously measure the soil infiltration characteristics through a disc infiltrometer. Results indicated that vegetation restoration types significantly affected initial infiltration rate (IIR), steady infiltration rate (SIR), and hydraulic conductivity (K), which ranged from 0.56 to 4.40, 0.32 to 2.86, and 6.48 × 10⁻³ to 0.47 mm h⁻¹, respectively (mean value: 2.72, 1.35, and 0.32 mm h⁻¹, respectively). The highest value of soil infiltration rate appeared in the EL, and the lowest value was observed in the RF. Root parameters including root length density and root surface density were highest in RG, and lowest in the control and RF, respectively. In addition, the conceptual path model explained 95%, 96%, and 96% of the variance in IIR, SIR, and K_s, with the goodness-of-fit index of 0.988, 0.988, and 0.997, respectively. This modeling determined biological crust thickness, soil organic matter content, root length density, and sand content as the major factors affecting the process of soil infiltration. These results enhance our understanding of the water erosion process under different vegetation restoration types in the severely eroded subtropical regions of South China.