Bashania fargesii bamboo is an important dominant understory species influencing community structure and regeneration of overstory trees, and it serves as an important food source for giant panda in the Qinling Mountains. B. fargesii invades old fields via clonal rhizome growth. However, the pattern of bamboo invasion into old fields and the role of physiological integration during bamboo expansion and regeneration, especially under giant panda herbivory are unclear.