Biomass and aboveground net primary production in a subtropical mangrove stand of Kandelia obovata (S., L.) Yong at Manko Wetland, Okinawa, Japan

Biomass and aboveground net primary production (ANPP) in a monospecific pioneer stand of a mangrove Kandelia obovata (S., L.) Yong were quantified. The estimated biomasses in leaves, branches, stems, roots, aboveground and total were 5.61 (3.68%), 28.8 (18.9%), 46.1 (30.2%), 71.8 (47.2%), 80.5 (52.8%) and 152 Mg ha(-1) (100%), respectively. Stem phytomass increment per tree was estimated using allometric relationships and stem analysis. Stem volume without bark of harvested trees showed a strong allometric relationship with D (0.1) (2) H (D (0.1), diameter at a height of one-tenth of tree height H) (R (2) = 0.924). Annual stem volume increment per tree showed a strong allometric relationship with D (0.1) (2) H (R (2) = 0.860). Litterfall rate ranges from 3.87 to 56.1 kg ha(-1) day(-1) for leaves and 0.177 to 46.2 kg ha(-1) day(-1) for branches. Seasonal changes of litterfall rate were observed, which showed a peak during wet season (August-September). Total annual litterfall was estimated as 10.6 Mg ha(-1) year(-1), in which 68.2% was contributed by the leaves. The ANPP in the K. obovata stand was 29.9-32.1 Mg ha(-1) year(-1), which is ca. 2.8-3.0 times of annual litterfall. The growth efficiency (aboveground biomass increment/LAI) was 5.35-5.98 Mg ha(-1) year(-1). The low leaf longevity (9.3 months) and high growth efficiency of K. obovata makes it a highly productive mangrove species.