N-Alkanes and their carbon isotopes (δ13C) reveal seasonal foddering and long-term corralling of pastoralist livestock in eastern Mongolia

Abstract

The compound-specific δ13C values of n-alkanes from pastoralist winter campsites in Mongolia have great potential to reconstruct dietary seasonality of livestock and local vegetation. We analysed leaf wax n-alkanes and their carbon isotope ratios in common fodder plants (Artemisia mongolica, Chenopodium album, Elymus dahuricus, Elymus sibiricus and Stipa sibirica) fed to domesticates during the winter months, and also in topsoils (0–8 cm) from four livestock corrals in northern and southern Mongolia. n-Alkanes identified in fresh plant parts reflect signatures with mean δ13C stable isotope values of individual n-alkanes typical for C3 plants (−34.1‰). Plants from forest- and desert-steppe exhibit similar mean n-alkane δ13C values but significantly wider isotopic variation in the desert steppe flora. The non-anthropogenic control samples exhibit δ13C mean values significantly higher from that of dung deposits and fresh plants for the same regions. Our data support previous research that n-alkanes profiles and their carbon isotopic values vary depending on the local vegetation and environment, while simultaneously demonstrating how anthropogenic activity, such as corralling of livestock, is recorded in the n-alkane of domesticates dung validating the use of biomarker studies in pastoralist archaeological contexts for distinguishing seasonal foddering, local environmental data and to an extent grazing habitats.