Photosynthetic Capacity and Water-Use Characteristics of Mangrove and Semi-Mangrove Species Inferred from Gas Exchange and A–Ci Analysis Under Field Conditions

This study compared net photosynthesis (A), water-use efficiency (WUE), intrinsic water-use efficiency (iWUE), and A–Ci curve-derived photosynthetic parameters (maximum carboxylation rate, Vcmax; maximum electron transport rate, Jmax) across nine mangrove and semi-mangrove species at a tropical coastal site in Bali, Indonesia. Gas exchange measurements were conducted using portable photosynthesis systems (LI-6400 and LI-6800), and A–Ci curves were fitted to the Farquhar–von Caemmerer–Berry (FvCB) model. Sonneratia alba Sm. exhibited the highest A (15.29 ± 2.39 μmol m−2 s−1), suggesting comparatively high photosynthetic performance, while Hibiscus tiliaceus L. and Pongamia pinnata (L.) Pierre showed the highest iWUE values (88–97 μmol mol−1), indicating relatively efficient carbon gain per unit stomatal conductance. Significant overall interspecific variation was detected in Vcmax and Jmax (p=0.003 and p=0.016, respectively). The observed interspecific variation in A, iWUE, Vcmax, and Jmax suggests differences in photosynthetic characteristics and leaf-level water-use efficiency among species. These ecophysiological baseline data may contribute to species selection for mangrove restoration and to understanding physiological responses to environmental change in tropical coastal forests.