Study on the n-alkane patterns of five dominant forage species of the typical steppe grassland in Inner Mongolia of China

Abstract

The alkane patterns of the dominant forage species of the typical steppe grassland in Inner Mongolia were clarified, and the effects of species, sampling time and site on the concentrations of alkanes were evaluated. The results showed that alkanes with odd-numbered carbon chains in the range C 25 (n-pentacosane)–C 35 (n-pentatriacontane) were predominant in cuticular wax in five dominant grasses of the typical steppe. The C 31 (n-hentriacontane) alkanes were always present in the highest concentration in the grass species, especially in the Stipa daicalensis and Stipa grandis . Samples of Artemisia frigida contained not only high concentrations of odd-chain alkanes, but also the even-chain ones compared with other species. The effects of species and sampling time on alkane concentrations were significant, accounting for 0·912 and 0·067 of the total variance, respectively. The site effects on odd-chain alkanes were less than on even-chain. The results of principal component analysis indicated that the patterns of alkane concentrations in the five dominant species could be clearly distinguished during the whole growing season. Therefore, it should be possible to achieve accurate and precise estimations of intake and diet composition of grazing animals of the typical steppe grassland in Inner Mongolia using the alkane technique.