Resource Allocation among Clonal Shoots of the Fire-Tolerant Shrub Gaylussacia baccata

Movement of resources among ramets allows clonal plant species to respond to environmental heterogeneity in time and space. The response is constrained by clonal architecture and mechanisms of intraclonal transport. In this study, rhizomes and clonal shoots of a fire-tolerant shrub (Gaylussacia baccata) were experimentally clipped in fifteen combinations (treatments). Carbon movement was inferred from the location and vigor of resprouting. In isolated shoots, resprout vigor was proportional to the length of the attached rhizome. Pairs of shoots connected by rhizomes appeared to compete for clonal support, showing decreased resprouting vigor relative to isolated shoots. Resprouting was also diminished by connection to established shoots, contrary to the expectation of the source/sink model. Vigor was not significantly related to the distance between connected shoots or the presence of rhizome branching points, indicating a very high degree of resource mobility within the clonal network. These findings suggest that the critical movement of resources is between rhizome storage and shoots rather than among clonal shoots - a pattern which would allow rapid regrowth and stable occupation of space despite widespread ramet destruction by fire.