Sahadev Sharma

Comparative reproductive phenology of subtropical mangrove communities at Manko Wetland, Okinawa Island, Japan

ABSTRACT We aimed to investigate and compare the reproductive phenology of Bruguiera gymnorrhiza, Kandelia obovata, and Rhizophora stylosa in subtropical area, over 5 years. The three mangrove species of the Rhizophorace family yielded reproductive organs throughout the entire annual cycle, with the exception of K. obovata. In case of B. gymnorrhiza, flowers were observed throughout the year, with a massive production in September, whereas propagule production was highest in July. Reproductive organs of K. obovata followed a very specific monthly periodicity. The highest production of flowers, fruits were observed in July, and massive production of propagule was observed in September for R. stylosa. The highest number of flowers was recorded in R. stylosa followed by K. obovata and B. gymnorrhiza. However, propagule setting was lowest in R. stylosa as compared to other two species. The largest propagule was also observed in R. stylosa. This was significantly different from that of other two species. Multiple regression analysis showed that reproductive organs of the three species were pronouncedly influenced by monthly mean air temperature and day length. Mean production of reproductive organs in B. gymnorrhiza, K. obovata, and R. stylosa contributed 37.5%, 18.7%, and 21.5% to the total litterfall, respectively.