N-alkane profiles of common rangeland species in northern China and the influence of drying method on their concentrations

Abstract

Plant wax alkanes have been used as internal markers to estimate diet composition of grazing animals. However, alkane contents in samples may vary depending on the drying method used. This study was undertaken to determine the alkane profiles and concentrations of 17 common range land species in northern China with two different drying methods. The results showed that regardless of drying methods, the odd-chain alkanes, particular C29 and C33, predominated in cuticular wax in all 17 common species and their component plant parts. The alkane patterns of plant species within the same genus were relatively similar and the differences in alkanes between stem and leaf were generally smaller than those between inflorescences and leaf or stem. The influence of drying methods on alkane concentrations varied depending on family and individual alkane. The effect of drying methods on C29 seemed to be smaller than other alkanes in all the samples. The oven-dry method produced higher concentrations (P < 0.05) in the three major alkanes (C23, C31 and C33) in the Gramineae family than the freeze-dry method. Therefore, studies dealing with alkane concentrations should use the same drying method for all samples. Key words: Alkane pattern, steppe grassland, oven-dry, freeze-dry