Effects of Extreme Temperature and Precipitation Events on Daily CO 2 Fluxes in the Tropics.

The effects of anomalous weather conditions (such as extreme temperatures and precipitation) on CO₂ flux variability in different tropical ecosystems were assessed using available reanalysis data, as well as information about daily net CO₂ fluxes from the global FLUXNET database. A working hypothesis of the study suggests that the response of tropical vegetation can differ depending on local geographical conditions and intensity of temperature and precipitation anomalies. The results highlighted the large diversity of CO₂ flux responses to the fluctuations of temperature and precipitation in tropical ecosystems that may differ significantly from some previously documented relationships (e.g., higher CO₂ emission under the drier and hotter weather, higher CO₂ uptake under colder and wetter weather conditions). They showed that heavy precipitation mainly leads to the strong intensification of mean daily CO₂ release into the atmosphere at almost all stations and in all types of study biomes. For the majority of considered tropical ecosystems, the intensification of daily CO₂ emission during cold and wet weather was found, whereas the ecosystems were predominantly served as CO₂ sinks from the atmosphere under hot/dry conditions. Such disparate responses suggested that positive and negative temperature and precipitation anomalies influence Gross Primary Production (GPP) and Ecosystem Respiration (ER) rates differently that may result in various responses of Net Ecosystem Exchanges (NEE) of CO₂ to external impacts. Their responses may also depend on various local biotic and abiotic factors, including plant canopy age and structure, plant biodiversity and plasticity, soil organic carbon and water availability, surface topography, solar radiation fluctuation, etc. [ABSTRACT FROM AUTHOR]