DIFFERENTIAL GROWTH AND VEGETATIVE REPRODUCTION OF TWO CO-OCCURRING EMERGENT MACROPHYTES ALONG

摘要

Differential responses of growth and vegetative reproduction among coexisting species to water-level fluctuation mightexplain their distribution patterns in wetlands. In the present study, we investigated the effect of water-level, ranging fromdry to flooded conditions, on the vegetative reproduction of 2 coexisting rhizomatous species, Carex brevicuspis C. B.Clarke and Polygonum hydropiper Linnaeus, at Dongting Lake wetlands, China. Carex brevicuspis exhibited optimalgrowth and vegetative reproduction when the aboveground parts were not submerged (at -40 cm to 0 cm water level), butremained quiescent under flooded conditions (at 20cm and 40cm water level). In comparison, P. hydropiper was sensitive tochanges in water level, with an almost linear decline in biomass and rhizome production as the water level increased from -40cm to 40cm. In general, there was less change in biomass production, biomass allocation, and vegetative reproduction forC. brevicuspis compared to P. hydropiper at different water levels. This result indicates that C. brevicuspis is more tolerantof water stress than P. hydropiper; therefore, C. brevicuspis is likely to have a wider distribution in wetlands, with the latterspecies embedding in the stands of the former species.