Soil water flow behavior generally includes two forms, preferential flow and matrix flow. The active degree of water flow directly affects solute flow, groundwater exchange and plant water uptake. In this study, we analyzed the soil water flow patterns and driving mechanisms in three different forest types (BF, MF and PF) in the subtropical forest succession sequence, based on the National Field Scientific Observation and Research Station of the Dinghushan Forest Ecosystem in Guangdong, China. Results show that although soil connectivity (e.g., porosity) and water infiltration capacity are better in the first two forest types than in Pine forest, however, soil water flow patterns and preferential flow levels do not show the same trend, mainly due to the complex distribution of soil pores. Plant roots, fractures, gravels and caves are the key factors contributing to the formation of macropores, and thereby their distribution patterns influence the pathways of water flow and the degree of preferential flow. From the stained profiles, the distribution of gravel, roots and fissures in the soil was not uniform across the nine sampling sites in the three forest types, and these had a profound effect on the water flow pathways, for example the degree of preferential flow (PF-fr, LI, PI) showed varying degrees of variation (Figure 1). Therefore, this study provides hydrological foresight for carrying out forest soil and water resource management.

The results of this study were published as 'Changes in soil infiltration and water flow paths: Insights from subtropical forest succession sequence' in Catena (IF2022= 6.367). Postdoctoral Fellow Dr. Wanjun Zhang is the first author of the paper, and Prof.  Juxiu Liu is the corresponding author. The research was supported by the Guangdong Provincial Key R&D Programme, the National Natural Science Foundation of China and the Postdoctoral Fellowship.

Figure 1. Distribution of soil water flow paths at nine samples in three forest types