Thermal acclimation of leaf respiration is consistent in tropical and subtropical populations of two mangrove species.

This article investigates whether tropical and subtropical populations of two New World mangrove species, Avicennia germinans and Rhizophora mangle, differ in growth responses to temperature and thermal acclimation of leaf respiration (R). Seedlings from tropical (Belize) and subtropical (Florida) origins were grown under ambient and experimentally warmed conditions at the species' northern range limit, with measurements taken over ~10 months. Results showed that warming increased growth and productivity more in tropical Avicennia than subtropical populations, indicating temperature adaptation at the whole-plant scale, while Rhizophora populations responded similarly. Both species exhibited thermal acclimation of leaf respiration consistent across populations and treatments, though populations differed in seasonal adjustments of the temperature sensitivity of respiration (Q10). Additionally, tropical Avicennia were more susceptible to freeze damage than subtropical ones, whereas Rhizophora populations showed equal freeze susceptibility. The study concludes that while growth responses reflect temperature adaptation, thermal acclimation of leaf respiration is largely conserved across populations from different thermal environments.