Abstract

Mangrove plants are found in tropical and sub-tropical tidal flats, and their limited distribution may be related to their responses to growth temperatures. However, the mechanisms underlying these responses have not been clarified. Typical species of Indo--Pacific mangroves, Bruguiera gymnorrhiza and Rhizophora stylosa, differ in their distribution ranges. Here, we grew these species at different temperatures and analyzed growth and respiration parameters. Relative growth rate of both species increased with growth temperature due to changes in physiological parameters such as net assimilation rate and respiration rate rather than to changes in structural parameters. At low growth temperature, root respiration rate and nitrogen uptake rate were lower in R. stylosa than in B. gymnorrhiza roots, leading to slower growth and higher sensitivity to low temperature of R. stylosa. Biomass allocation to leaves and roots was also lower in R. stylosa at any temperature. These characteristics of R. stylosa would result in lower relative growth rate of whole plant and to different distribution patterns of the two species.