Typhoons exert significant but differential impacts on net ecosystem carbon exchange of subtropical mangrove forests in China

摘要

Typhoons are very unpredictable natural disturbances to subtropical mangroveforests in Asian countries, but little information is available on how thesedisturbances affect ecosystem level carbon dioxide (CO₂) exchange ofmangrove wetlands. In this study, we examined short-term effect of frequentstrong typhoons on defoliation and net ecosystem CO₂ exchange (NEE) ofsubtropical mangroves, and also synthesized 19 typhoons during a 4-yearperiod between 2009 and 2012 to further investigate the regulationmechanisms of typhoons on ecosystem carbon and water fluxes followingtyphoon disturbances. Strong wind and intensive rainfall caused defoliationand local cooling effect during the typhoon season. Daily total NEE valuesdecreased by 26–50% following some typhoons (e.g., W28-Nockten,W35-Molave and W35-Lio-Fan), but significantly increased (43–131%)following typhoon W23-Babj and W38-Megi. The magnitudes and trends of dailyNEE responses were highly variable following different typhoons, which weredetermined by the balance between the variances of gross ecosystemproduction (GEP) and ecosystem respiration (RE). Furthermore, results fromour synthesis indicated that the landfall time of typhoon, wind speed andrainfall were the most important factors controlling the CO₂ fluxesfollowing typhoon events. These findings indicate that different types oftyphoon disturbances can exert very different effects on CO₂ fluxes ofmangrove ecosystems and that typhoon will likely have larger impacts oncarbon cycle processes in subtropical mangrove ecosystems as the intensityand frequency of typhoons are predicted to increase under future globalclimate change scenarios.