Florida mangroves show no evidence of thermal acclimation of leaf respiration: implications for coastal carbon cycling and future climate

Research Authorship:

Kylie Harris, Jeff Chieppa, Matt Sturchio, Michael Aspinwall

Faculty Mentor:

Dr. Michael Aspinwall | College of Arts and Sciences | Department of Biology

Abstract:

Temperature controls of physiological processes that regulate C cycling in mangrove ecosystems remain understudied. New studies that investigate mangrove sensitivity to temperature could improve representation of coastal C cycling in global scale models. Respiration represents the second largest C flux between vegetation and the atmosphere, and roughly 50% of plant respiration comes from leaves. Leaf respiration increases with temperature, but thermal acclimation can dampen this response, and mitigate the positive feedback between temperature, respiration, and atmospheric CO2. We tested whether thermal acclimation of leaf respiration (R) to seasonal temperature changes and experimental warming is similar among three common mangrove species (Avicennia germinans, Rhizophora mangle, Laguncularia racemosa). Over seven months we repeatedly measured the short-term temperature response of leaf R on seedlings of each species grown under ambient and warmed treatments. Species differed in average rates of R measured at 25 °C and the temperature sensitivity of leaf R (Q10) when seasonal temperatures were high, but these differences disappeared when seasonal temperatures were low. Importantly, none of the species showed evidence of reduced R at 25 °C or reduced Q10 values at warmer growth temperatures, suggesting that mangroves may not adjust to rising temperatures, thereby accelerating a positive feedback between warming and atmospheric CO2.