Greater trend and interannual variability in productivity of mangroves compared to terrestrial forests

Abstract

AbstractMangrove forests are highly productive ecosystems with important potential to offset anthropogenic greenhouse gas emissions. Due to their location in the tidal environment and unique ecophysiological characteristics, mangroves are expected to respond differently to climate change compared to terrestrial forests. However, the difference remains largely elusive at the global scale, though the knowledge is critical to guide the forest conservation over coastal regions. Here we examine long-term trend and interannual variability of the productivity of global mangrove forests and their nearby terrestrial counterparts, the evergreen broadleaf forests (EBFs), over the past two decades using satellite observations. We find while both mangroves and EBFs experienced significant increases in their productivity, mangroves exhibited stronger trends and interannual variability in productivity than EBFs on 71.79% and 73.49% of their co-occurring coasts. The difference in NIRv trend is attributed to the stronger CO2fertilization effect on mangrove photosynthesis, while the discrepancy in interannual variability is attributed to the higher sensitivity of NIRv to variations in precipitation and sea level. Our results indicate that mangroves will have a faster increase in productivity than terrestrial forests in a CO2-rich future but may suffer more from deficits in water availability, highlighting a key difference between terrestrial and tidal ecosystems in their responses to climate change.