Figure 3
Leaf wax δDn-alkane values in living angiosperms along a latitudinal gradient in the North Hemisphere.
Comparisons of leaf wax δDn-alkane values (n = 233) between herbaceous plants and woody plants and the precipitation average δD were presented as δD = −0.037 × (latitude)2 + 1.1674 × (latitude) −35.423 from Liu and Yang (2008) (a). Comparisons between monocotyledonous and dicotyledonous species based on our expanded database (n = 503). Notice, the observed higher δDn-alkane values in Stiffkey saltmarsh (Eley et al., 2014) may be due to the fact that samples were obtained from a salt marsh (b). The parallel εwax-p values in dicotyledonous and monocotyledonous species are insensitive to variations of precipitation δD values, suggesting different biosynthetic processes between eudicots and monocots (c).
