Maintenance of leaf temperature and the optimisation of carbon gain in relation to water loss in a tropical mangrove forest

Studies were conducted on leaves of mangrove species growing in a tidal swamp on Hinchinbrook Island, N Queensland; Bruguiera gymnorrhiza, Ceriops tagal var. australis, Rhizophora apiculata, R. lamarckii and R. stylosa. Rates of assimilation of CO₂ were maximal at leaf temperatures of c 30°C. The species operated with higher water use efficiencies than do most C₃ species, and water-use characteristics became increasingly conservative with increase in the salinity tolerance of the species. Changes in inclination, area and succulence of leaves contributed to maintenance of leaf temperatures near air temperatures with minimal evaporative cooling. Interspecific differences in water-use characteristics, and their relationship to the maintenance of favourable leaf temperatures, could affect the competitive abilities of mangroves and the structure of mangrove forests. -from Authors