"ENSO Drives interannual variation of forest woody growth across the tropics"

Dr. Sami Rifai
Investigador de la Universidad de Oxford
Meteorological extreme events such as El Niño events are expected to affect tropical forest net primary production (NPP) and woody growth, but there has been no large-scale empirical validation of this expectation. We collected a large high–temporal resolution dataset (for 1–13 years depending upon location) of more than 172 000 stem growth measurements using dendrometer bands from across 14 regions spanning Amazonia, Africa and Borneo in order to test how much month-to-month variation in stand-level woody growth of adult tree stems  can be explained by seasonal variation and interannual meteorological anomalies. We find that tropical forest woody growth responds differently to meteorological variation between tropical forests with a dry season (where monthly rainfall is less than 100 mm), and aseasonal wet forests lacking a consistent dry season. Woody growth in seasonal tropical forests is primarily related to seasonal variation in temperature, vapour pressure deficit, in addition to interannual anomalies of soil water deficit and shortwave radiation. In contrast,  Aseasonal wet forest woody growth is best predicted by the interannual anomalies of vapour pressure deficit, water deficit and shortwave radiation. In total, we predict the total live woody production of the global tropical forest biome to be on average 2.16 Pg C yr, where interannual variation is highly related to the El Niño 3.4 index.