Comparison between the mean α-abundances derived by the AMBRE pipeline and the abundances of the individual α-elements determined by Porto. The largest departures from the 1-to-1 line are found for the Si  and Ca  abundances and could explain the departure observed in Fig. 9 for the most metal-poor stars. As in Fig. 10, stars with T_eff> 6000 K are plotted in the panels with blue dots; stars with [Fe / H ]< − 0.4 dex are the red dots.