Mechanical Characteristics of Pinus massoniana Roots in Different Management Areas in Changting County, China

The tensile properties of roots are influenced by genetic and environmental factors. As a pioneer tree species used for the ecological restoration of red-soil erosion areas in southern China, the factors affecting the tensile properties of Pinus massoniana roots, which remain unknown, and the mechanical basis of root consolidation should be investigated. The aim of this study was to compare the tensile properties, chemical composition, and microstructure of Pinus massoniana roots under different site conditions and elucidate the mechanisms by which microscopic factors influence the tensile properties of roots. The results showed that as the root diameter increased, the tensile resistance of Pinus massoniana roots increased as a power function and tensile strength decreased as a power function. The tensile properties of the Pinus massoniana roots in managed (i.e., contour grass–shrub and grass–shrub–arbor plots) plots were stronger than those in strongly eroded land. The hemicellulose, cellulose, holocellulose, and lignin content as well as the lignin-to-cellulose ratio of the Pinus massoniana roots varied between the strongly eroded land and managed plots. Moreover, the cross-sectional area of the Pinus massoniana roots in the managed plots was slightly higher than that in the strongly eroded land. Redundancy analysis and structural equation modeling revealed that the tensile properties of Pinus massoniana roots were mainly influenced by the epidermis, resin ducts, and hemicellulose content. These findings provide a basis for the selection of tree species for ecological restoration in the red-soil erosion areas in southern China.
The data consisted of tensile tests, chemical composition, and microstructure data of the three sample plots.A single tensile test was performed using a universal tensile test machine, with reference to the National Standard GB/T228-2002 (Metallic Materials—Tensile Testing at Ambient Temperature). A crude fiber content tester (model SLQ-202, Shanghai Fiber Inspection Instrument Co., Ltd.) was used for the chemical composition analysis.The root segments of P. massoniana were embedded into 3–5 permanent paraffin sections for the observation of the root microstructure (Liao et al., 2023). A panoramic scanner (PANNORAMIC 250 Flash III DX; 3DHISTECH, Budapest, Hungary) was used to collect root microstructure images, which were preprocessed and saved in the Case Viewer software. The microstructure and cell characteristics of the roots were observed and analyzed, and the percentage of each microstructure relative to the cross-sectional area of the entire root system was measured.Perform correlation, redundancy analysis, and structural equation modeling of data.