Vegetated coastal ecosystems (saltmarsh, mangroves) make a large contribution to global net primary productivity and C cycling despite covering a small proportion of the earth’s surface. Yet, our understanding of C cycling processes over space and time and in response to temperature remain limited for these ecosystems. At the global scale, respiration is the second largest flux of C (behind photosynthesis), and ~50% of respiration comes from leaves. Respiration is also a key parameter for global models that predict climate-carbon cycle interactions. But respiratory responses to temperature in marsh and mangrove species remain uncertain. Here, we repeatedly measured short-term temperature responses of leaf respiration in a C4 marsh grass species (Spartina alterniflora) and a C3 mangrove species (Avicennia germinans) growing under ambient temperatures and experimental warming at two sites in Florida. We tested whether marsh grasses and mangroves show similar acclimation of leaf respiration to seasonal temperature changes at sites differing in temperature seasonality, and whether acclimation is consistent between plants grown under ambient and warmed conditions.
Results/Conclusions
Across both sites, Spartina showed consistent thermal acclimation of leaf respiration in response to both seasonal temperature changes and climate warming. Specifically, rates of respiration at a common measurement temperature were lower during warm time periods and under experimental warming. In contrast, at both sites, Avicennia showed little evidence of thermal acclimation of leaf respiration in response seasonal temperature changes and warming. These results indicate that thermal acclimation might reduce respiratory C fluxes from marsh grasses in response to warming. However, acclimation was limited in Avicennia indicating that respiratory C fluxes from mangroves might increase substantially with climate warming. Our results provide new data that may improve predictions of carbon cycling processes in vegetated coastal ecosystems over space and time.