Interactions between soil properties and the rhizome-root distribution in a 12-year Moso bamboo reforested region: Combining ground-penetrating radar and soil coring in the field.

Moso bamboo (Phyllostachys pubescens) plays an important role in mitigating climate change and ameliorating soil degradation because of its high carbon sequestration capacity and erosion resistance. Its strong underground rhizome-root systems form the basic framework of the aboveground system of Moso bamboo forest and define the basic ecological characteristics. However, studies on the relationship between the spatial distribution of roots and soil resources have often been neglected due to methodological limitations. The objective of this study was to test the detectability of rhizomes in the field by ground-penetrating radar (GPR) and to understand the interactions between rhizome-root systems and soil characteristics. The rhizome-root system distribution was investigated using GPR; and the soil texture, soil organic carbon and soil nutrients were investigated using a soil coring method to prepare 50-cm soil profiles. A few key findings were emphasized. First, the rhizome-root system was mainly distributed over a soil depth of 0-30 cm; and the rhizomes were larger in diameter (often greater than 1.0 cm). Therefore, GPR can accurately detect rhizomes in the field, making the non-invasive and long-term estimation of rhizome biomass and monitoring of changes in rhizome dynamics possible under field conditions. Second, the spatial heterogeneity of the soil moisture content, alkaline hydrolysed nitrogen and available phosphorus had a greater effect on the rhizomes spatial distribution than did the spatial heterogeneity of other soil characteristics. The rhizomes clonal growth led to increases in soil organic carbon, which promoted the amelioration of degraded soil. Third, the results provide insights for bamboo forest management, such as the application of GPR to prevent bamboo invasion and to determine the appropriate fertilizer level for a rhizome system. More field tests are needed to validate the application of GPR to rhizome systems and enhance the detection and quantification of rhizome systems in bamboo forest ecosystems.