Abundance ratios of α-elements Mg, Si, Ca, and Ti i as functions of the effective temperature. The average of [α/Fe] ratios are shown in the last two panels on the right column (including and excluding the Mg abundance from the mean, respectively). Red circles are for stars observed with GIRAFFE, while blue squares indicate stars with UVES spectra. Internal star-to-star errors are listed in Table 5 and Table 4, respectively.