Fig. 2. Biometric estimates of various components of carbon fluxes.

Both Amazonia plots (blue dot) and West African plots (yellow triangle). Local polynomial regression fitting lines (LOESS) are drawn for each region. Each dot represents one one-hectare plot). The error bars represent the uncertainty of estimates (see Supplementary Method for uncertainty estimation). The x-axis is a factorial order of aridity. From wettest (left) to driest (right), sites were ranked by maximum climatological water deficit (MCWD mm year⁻¹). Within sites, plots not separable by MCWD were ranked by in situ measured surface soil moisture, which reflects local soil moisture retention and under canopy humidity (Table S1). The curves and their uncertainties (grey zone) were drawn by local polynomial regression for illustration purposes only; they do not contain relevant statistical information. Source data are provided as a Source Data file. The figure shows A net primary productivity (NPP), B gross primary productivity (GPP), C carbon use efficiency (CUE = NPP / GPP), D autotrophic respiration, E stem biomass, F leaf area index, G NPP by litterfall H leaf respiration I stem NPP J stem respiration K fineroot NPP and L rhizosphere respiration. See Supplementary Data 1 for the definition of each carbon flux component.