Title: Effects of fragmentation on the survival and growth of the invasive, clonal plant Alternanthera philoxeroides
Abstract: The capacity of small clonal fragments to survive and grow is a major factor in the spread of clonal plants, especially aquatic species. This study of the introduced, invasive, amphibious, stoloniferous herb Alternanthera philoxeroides in China tested the effects of fragment size, of loss of the stolon apex, and of the original position of a fragment within a clone before fragmentation on the survival and growth of fragments in a greenhouse experiment. The stolon internodes of plants consisting of one stolon with 5 ramets were severed in all 16 possible patterns, generating fragments of 1–5 ramets. These 16 fragmentation treatments were crossed with removal of the stolon apex. Fragmentation and apex removal did not affect total growth of plants, but more highly fragmented plants produced smaller, more numerous ramets. The survival of fragments consisting of one original ramet was about 85%, compared to 100% survival of fragments with 5 original ramets. Fragments consisting of the youngest ramets along the original stolon grew more than fragments of the same size that consisted of older ramets. These effects of fragmentation on growth provide new evidence for clonal integration of the rate at which connected ramets produce new ramets and novel evidence that fragments produced from different portions of clones have different potential for spread. They further suggest that detachment of small groups of distal ramets along stolons in the field might be very effective in spreading the species and that a trade-off between the number and the size of new ramets produced by fragments may represent an adaptive, plastic response to disturbance. Results do not recommend intentional fragmentation of clones as a means of controlling the rate of growth of this invasive species but suggest that incidental fragmentation may not increase its growth in mass, although it may increase its rate of spread. [Bi-Cheng Dong, Peter Alpert, Wei Guo and Fei-Hai Yu (2011). Effects of fragmentation on the survival and growth of the invasive, clonal plant Alternanthera philoxeroides. Biological Invasions, online 26 Nov., DOI: 10.1007/s10530-011-0141-5]