MEPS 320:131-139 (2006)  -  doi:10.3354/meps320131

Canopy photosynthesis, canopy respiration and surplus production in a subtropical mangrove Kandelia candel forest, Okinawa Island, Japan

Rempei Suwa, M. Nabiul I. Khan, Akio Hagihara*

Laboratory of Ecology and Systematics, Faculty of Science, University of the Ryukyus, Okinawa 903-0213, Japan
*Corresponding author. Email:

ABSTRACT: The gross photosynthesis and respiration rates of leaves at different canopy depths in a Kandelia candel (L.) Druce stand were measured monthly over 2 yr. The maximum gross photosynthesis and dark respiration rates of the leaves existing at the top of the canopy were respectively 2 to 4 times and 2 to 7 times those of the bottom leaves throughout the year. The maximum gross photosynthesis and dark respiration rates showed positive correlations with leaf nitrogen content. Daily canopy gross photosynthesis and respiration showed apparent seasonal changes. The annual canopy gross photosynthesis, canopy respiration and surplus production were estimated as 102.9 ± 1.5, 44.0 ± 2.1 and 58.9 ± 0.6 (SE) t CO2 ha–1 yr–1, respectively. The energy efficiency for the annual gross photosynthesis was 2.4 ± 0.1 (SE)%. Optimum leaf area index (LAI) for annual surplus production was 4.54 m2 m–2, which was almost the same as the actual LAI of 4.50 m2 m–2. The neglect of seasonal changes in the physiological traits of leaves resulted in estimates that were 65 to 125% of the annual surplus production. The relationship of gross primary production (GPP) to the product of LAI and warmth index (WI) was similar to those established for various types of terrestrial forests in perhumid climates.


KEY WORDS: Kandelia candel · Photosynthesis · Respiration · Surplus production · Optimum leaf area index · Sun leaf · Shade leaf · Subtropical mangrove forest


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