Effects of plant roots on soil preferential pathways and soil matrix in forest ecosystems

To characterize effects of plant roots on preferential flow (PF), we measured root length density (RLD) and root biomass (RB) in Jiufeng National Forest Park, Beijing, China. Comparisons were made for RLD and RB between soil preferential pathways and soil matrices. RLD and RB declined with the increasing soil depth (0–10, 10–20, 20–30, 30–40, 40–50, 50–60 cm) in all experimental plots. RLD was greater in soil preferential pathways than in the surrounding soil matrix and was 69.5, 75.0 and 72.2 % for plant roots of diameter (d) <1, 1 < d < 3 and 3 < d < 5 mm, respectively. Fine root systems had the most pivotal influence on soil preferential flow in this forest ecosystem. In all experimental plots, RB content was the sum of RB from soil preferential pathways and the soil matrix in each soil depth. With respect to 6 soil depth gradient (0–10, 10–20, 20–30, 30–40, 40–50, 50–60 cm) in each plot, the number of soil depth gradient that RB content was greater in soil preferential pathways than in the soil matrix was characterized, and the proportion was 68.2 % in all plots.