Phenology of Zostera caespitosa in Tongyeong on the coast of Korea

Abstract

The variations of morphological features, density and biomass of vegetative shoots and characteristics of reproductive shoots of Zostera caespitosa were examined in Tongyeong, Korea. Morphological features such as leaf length, width and sheath length of Z. caespitosa showed significant seasonal variation (p < 0.001). The highest aboveground value was recorded in late spring to summer and the lowest value in winter. Density and biomass also showed seasonal variations. Annual average shoot density and biomass of Z. caespitosa were recorded as 1,223.4 leaf m−2 and 5,956.9 g w.w.m−2, respectively, and had the highest value in June and lowest values in November and January. Reproductive shoots were observed from April (13°C) to June (21°C). Pistils erected outside sheath, anther dehiscing and small embryos were found in April. Mature fruit and released seeds were found in May and June. These results suggest that this species had a high growth rate in late spring and early summer (15°C–20°C). Reproductive shoots of Z. caespitosa may initially appear at about 10°C in spring and seed have been released at about 20°C in fall.