Production and population ecology ofPhyllospadix iwatensis Makino. I. Leaf growth and biomass in an intertidal zone

In an intertidal zone on Choshi coast, Japan,Phyllospadix iwatensis Makino emerges at daytime in spring and summer, while at night time in winter. The plants therefore experience seasonally different stresses caused by emergence, for example, intense light, ultraviolet rays, extreme temperature and desiccation, all of which the plants are unable to avoid during daytime emergence. Seasonal changes in the biomass and LAI suggest that the optimum periods for growth ofP. iwatensis would be in March when the emergent period is short or nil and light availability is high while water temperature is not too low. Dense foliage and low canopy height ofP. iwatensis in the intertidal zone relieve the plant from the stresses in emergent periods and from the disturbance caused by strong water movement in some coastal areas with active wave action.