Higher benefits of clonal integration in rhizome-derived than in frond-derived ramets of the tropical fern Bolbitis heteroclita

摘要

Clonal integration between connected ramets within genets can increase their survival and growth. Different clonal plants form ramets in a variety of ways, and a number of species form more than one type of ramets. We tested for the first time whether effects of clonal integration can differ between different types of ramets within the same species. We compared effects of severing connections between ramets (i.e. preventing clonal integration) on the survival and growth of ramets produced along rhizomes and at the tips of fronds in a natural population of the fern Bolbitis heteroclita in a tropical seasonal rainforest in southwestern China. Severance strongly reduced the survival of both rhizome-derived and frond-derived ramets but reduced survival and the growth of surviving ramets much more in rhizome-than in frond-derived ramets. Rhizome-derived ramets were larger, allocated less dry mass to belowground structures, and had greater cross-sectional area of connecting vascular tissue. These results suggest that clonal integration increases performance of both rhizome-and frond-derived ramets of B. heteroclita, but that benefits of integration are greater in rhizome-derived ramets. This may be due to greater conductance in the connections to rhizome-derived ramets.