Variations of soil organic matters and plant cuticular waxes along an altitude gradient in Qinghai-Tibet Plateau

Aims This study aims to evaluate the variations of soil organic matter and plant leaf cuticular waxes along an altitude gradient at two mountains in the east side of the Qinghai-Tibet Plateau. Methods Surface soils were sampled along an altitude gradient (2600, 3000, 3400, 3800 and 4200 m). We analyzed the soil total organic carbon (TOC), dissolved organic carbon (DOC), soil lipids and leaf cuticular waxes in Kobresia humilis which distributed at all tested altitudes. Results A sharp concentration increase of TOC was observed when altitudes increased, whereas the proportions of DOC in TOC at low altitudes (3000 m and 2600 m) were significantly higher than those at higher altitudes. Altitudes also influenced the molecular weight, humification degree, aromaticity, and hydrophobicity of DOC molecular. Though soils at higher altitudes relatively had higher abundance of odd carbon alkanes and even carbon alcohols, soil lipid concentrations showed no significant difference between altitudes. Relatively higher total wax coverage at high and low altitude was observed on leaves of K. humilis. Conclusions The changes of altitudes at alpine ecosystem were associated with alterations of both quantity and quality of soil organic matter as well as leaf cuticular wax coverage, which contributed to their environmental adaptations.