Abstract
Background and aimsIn contrast to seeds, high sensitivity of vegetative fragments to unfavourable environments may limit the expansion of clonal invasive plants. However, clonal integration promotes the establishment of propagules in less suitable habitats and may facilitate the expansion of clonal invaders into intact native communities. Here, we examine the influence of clonal integration on the morphology and growth of ramets in two invasive plants, Alternanthera philoxeroides and Phyla canescens, under varying light conditions.MethodsIn a greenhouse experiment, branches, connected ramets and severed ramets of the same mother plant were exposed under full sun and 85% shade and their morphological and growth responses were assessed.Key resultsThe influence of clonal integration on the light reaction norm (connection×light interaction) of daughter ramets was species-specific. For A. philoxeroides, clonal integration evened out the light response (total biomass, leaf mass per area, and stem number, diameter and length) displayed in severed ramets, but these connection×light interactions were largely absent for P. canescens. Nevertheless, for both species, clonal integration overwhelmed light effect in promoting the growth of juvenile ramets during early development. Also, vertical growth, as an apparent shade acclimation response, was more prevalent in severed ramets than in connected ramets. Finally, unrooted branches displayed smaller organ size and slower growth than connected ramets, but the pattern of light reaction was similar, suggesting mother plants invest in daughter ramets prior to their own branches.ConclusionsClonal integration modifies light reaction norms of morphological and growth traits in a species-specific manner for A. philoxeroides and P. canescens, but it improves the establishment of juvenile ramets of both species in light-limiting environments by promoting their growth during early development. This factor may be partially responsible for their ability to successfully colonize native plant communities.
Highlights
Plant invasion is a threat to biotic diversity and ecosystem services worldwide [1,2,3]
Clonal integration modifies light reaction norms of morphological and growth traits in a species-specific manner for A. philoxeroides and P. canescens, but it improves the establishment of juvenile ramets of both species in lightlimiting environments by promoting their growth during early development
We addressed the effect of clonal integration on ramet physiology in A. philoxeroides and P. canescens in a previous study and found a species-specific pattern in the amount of maternal carbohydrate subsidy under contrasting light levels [35]
Summary
Plant invasion is a threat to biotic diversity and ecosystem services worldwide [1,2,3]. Whether clonal integration increases the competitive ability of plant invaders remains controversial [16,17,18,19,20,21,22], there is clear evidence that it improves the establishment (including survival and early stage growth) of juvenile ramets of plant invaders in habitats with low resource availability, adverse environmental conditions, or intense competition [20,23,24,25,26,27] These studies mostly contrasted the performance of connected and severed ramets (e.g. survival rate, biomass, stem number), but rarely examined the effect of clonal integration on morphological traits that are closely associated with acclimation to adverse conditions. We examine the influence of clonal integration on the morphology and growth of ramets in two invasive plants, Alternanthera philoxeroides and Phyla canescens, under varying light conditions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
