Bamboo Expansion Affects the Vertical Distribution and Phenotypic Plasticity of Root Systems of Native Cunninghamia lanceolata and Expanding Phyllostachys edulis in Middle-Southern China

Abstract It is commonly known that bamboo shoots reduce native diversity by spreading through neighboring communities via their rhizome systems. However, the mechanism of root interaction between native species and expanding bamboo is poorly understood. This study aims to explore the differences in parameters such as biomass vertical distribution and phenotypic plasticity of root orders between expanding species, specifically moso bamboo ( Phyllostachys edulis , Pe ), and native species, Chinese fir ( Cunninghamia lanceolate , Cl ), at different expansion levels. The results show a heterogeneous reaction to expansion effects. The root biomass of Chinese fir significantly decreased from CLS to PCM, while bamboo root biomass exhibited a similar but insignificant decreasing trend from PES to CPM. Both root systems remained concentrated at the uppermost layers, where the FRB ratio of Pe was higher than Cl , and the majority of phenotypic traits of Pe root systems were noticeably higher than that of Cl in both vertical and horizontal soil. Additionally, the study found that soil factors explained root traits well, with a cumulative variation ranging from 53.87–88.48%. The findings suggest that bamboo expansion affects spatial heterogeneity and niche differentiation of both native and expanding species. In terms of root distribution and plastic reaction, Chinese fir is at a disadvantage compared to expanding bamboo, which worsens its survival conditions.