Regeneration capacity of the small clonal fragments of the invasive Mikania micrantha H.B.K.: effects of the stolon thickness, internode length and presence of leaves.
Mikania micrantha H.B.K., one of the top 10 worst weeds in the world, is now spreading quickly in southern China. Disturbance can fragment and spread the stolons of M. micrantha. A greenhouse experiment was conducted in order to assess the regeneration capacity of single-node fragments with varying stolon thickness (diameters of 3.01, 2.49 and 1.96 mm), internode lengths (2 and 8 cm) and leaf presence status (with and without leaves). The results indicated that an increasing stolon thickness, internode length and the presence of leaves all increased the survival rate of the clonal fragments. An increasing stolon thickness, internode length and the presence of leaves also increased the growth of the clonal fragments and the presence of leaves exhibited the strongest effect. An increasing internode length and the presence of leaves also reduced the amount of time that was needed for emergence, while the effect of the stolon thickness was not significant. None of the effects of the interactions was significant, although the interaction between the stolon thickness and the internode length was nearly significant for fragment survival. These results suggest that M. micrantha has developed a strategy to cope with disturbance by storing reserves in the stolons and leaves, which could increase its regeneration capacity after fragmentation. Currently, the management of M. micrantha (such as manual or mechanical control) should avoid the generation of the small clonal fragments of M. micrantha, while repeated control with short time intervals is necessary in order to prevent reinvasion from the stolon fragments.