We present δDwax values from different forms of plants and soils, and δDsw values from soil water along the northern slope of Mount Taibai, China. The results show a highly negative linear correlation of the δDwax values for soils with altitude (R2 0.74) and we observed the same correlation for δDsw values of soil water with altitude (R2 0.68). The δDwax of living plants behaves like the soil, but does not exhibit a significant linear correlation with altitude (R2 0.11). The δDwax values of woody plants and grasses also show a similar trend with respect to altitude with significant and no linear correlation, respectively (R2 0.50 for woody plants and 0.17 for grass), which suggest that the "altitude effect" can not be well documented for the δDwax values of living plants, which may be due to differences in plant type and/or evapotranspiration controlled by the plant microclimate. The εwax-sw values of woody plants, grasses and soil show minor fluctuations with altitude. However, the εwax-sw and δDwax values of woody plants are roughly 51‰ and 50‰ more positive, respectively, than those of grasses, suggesting that an "altitude effect" could be documented in the δDwax of woody plants and grasses, with each responding independently to changes in precipitationalong the altitude transect. Additionally, the εwax-sw values of soil are relatively constant with altitude, suggesting that the altitudinal change in the proportions between woody plant and grass input to soils will likely change the relationship between the δDwax values of soil n-alkanes and altitude.
Bibliographical noteFunding Information:
We thank Zhou Youping and Zhao Jiangtao for assistance in the field. We are very grateful to Xu Langran for help in the identification of modern plant species. We also thank Y. Chikaraishi and an anonymous reviewer for comments, which greatly improved the manuscript. The research was supported by the National Science Foundation of China (Nos. 41073018, 40873011), the Chinese Academy of Sciences (No. KZCX2-YW-149), National Key Funds of China (No. 2010CB833400) and the Startup Foundation for Doctorate of Northwest University, China (No. PR10056).