Effects of plant types on terrestrial leaf wax long-chain n-alkane biomarkers: Implications and paleoapplications

Terrestrial leaf wax n -alkane biomarkers provide considerable insights into paleoenvironmental reconstruction. Over decades, a substantial number of field investigations were performed to constrain hydroclimatic factors that influence leaf wax n -alkane biomarkers to improve their utility for paleoenvironmental applications. However, a critical issue, the plant type effects, does exist which potentially affects the fidelity of leaf wax n -alkane biomarkers for paleohydroclimate calibration. Here we review the effects of plant types on terrestrial leaf wax n -alkane biomarkers from three aspects: leaf wax n -alkane distribution (wood vs. non-wood), hydrogen isotope (δ 2 H wax ; dicot vs. monocot) and carbon isotope (δ 13 C wax ; C 3 vs. C 4 ) biomarkers. Then we demonstrate the relationships between three forms of leaf wax n -alkane biomarkers, and provide examples of the cross-calibration among them in paleo-applications. The in-depth review of plant type effects on leaf wax n -alkane biomarkers will be helpful to interpret the hydroclimate and vegetation signals in the geologic past.