Stand Characteristics Rather than Soil Properties Contribute More to the Expansion of Moso Bamboo (Phyllostachys edulis) into Its Neighboring Forests in Subtropical Region

Moso bamboo (Phyllostachys edulis), once highly praised worldwide, has been found to be a problematic species due to its unconstrained expansion into adjacent woodlands and negative effects on the function services of forest ecosystems. To determine the major factors affecting bamboo expansion into neighbor woodlands, we investigated the expansion characteristics of moso bamboo and the properties of stand structure and soil for 58 bamboo–woodland interfaces (BWIs) across Jiangxi province in China. Then, we analyzed the relationships between the variables of bamboo expansion and the properties of interfaces through a redundancy analysis. The characteristics (the expansion distance and the number and size of new culms) of moso bamboo expansion into disturbed forests were more significant (p < 0.01) than those into non-disturbed forests. The bamboo expansion into deciduous broad-leaved forest was much faster (1.33 m/yr) than evergreen broad-leaved forest (0.82 m/yr) and needle-leaved forest (1.08 m/yr). The characteristics of stand structure had more direct explanatory power (58.8%) than soil properties (4.3%) and their interaction (10.0%) for the variations in bamboo expansion. The canopy closure of recipient forests was identified as the most significant factor negatively correlated to bamboo expansion. The number of parent culms and the ratio of deciduous to evergreen trees ranked in sequence, and both imposed positive effects on the expansion. Regarding soil properties, only the water content was identified for its explanatory power and negative influence on bamboo expansion. Our findings illustrated that the expansion of moso bamboo showed remarkable variations when facing different woodlands. Stand characteristics (canopy closure, canopy height, etc.) of good explanatory power were the major variables affecting the expansion of moso bamboo. In order to control the expansion of bamboo and protect woodlands, disturbances (extracting timber, girdling trunks) should be prevented in bamboo–woodland interfaces.