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The temperature gradient along the altitude transect of Mt.Jianfengling provides a good opportunity to establish and evaluate the microbial lipid-based environmental proxies.The soils collected from 14 different altitudes of Mt.Jianfengling contain abundant microbial fatty acids and fatty alcohols,including iso/anteiso fatty acids(i/aC12:0–i/aC19:0),10-Me-C16:0 fatty acid,iso/anteiso fatty alcohols(i/aC13–iC26),10-Me-C16:0 fatty alcohol and unsaturated fatty alcohols,which can indicate a strong microbial activity in the Jianfengling soils.The branched and unsaturated fatty alcohols can be only detected when saponification is performed,implying that these lipids are present as the constituents of bacterial wax esters in the soils.The ratio of aC15/iC15 fatty acids is positively correlated with altitude,suggesting that the decrease in temperature can induce the increase in the relative abundance of anteiso C15 fatty acid.In contrast,the ratio of aC15/iC15 fatty alcohols and of aC15/nC15 fatty alcohols both decrease with increased altitude or decreased temperature.Similarly,the ratio of nC18:1/nC18:0 fatty alcohols also decreases with decreased temperature,which is opposite to the previous observation that unsaturation of fatty acids in microorganism increases in response to decreased temperature.Besides,the average chain length(ACL)of long chain fatty alcohols(C22–C30)from leaf waxes and carbon preference index(CPI)of all n-fatty alcohols are also significantly correlated with altitude or mean annual temperature,demonstrating their potential for paleoclimate reconstruction.The correlation of microbial fatty acids and alcohols as well as ACL and CPI of plant wax-derived fatty alcohols with altitude may provide novel ways to reconstruct paleotemperature and paleoaltimetry.
The temperature gradient along the altitude transect of Mt. Jianfengling provides a good opportunity to establish and evaluate the microbial lipid-based environmental proxies. The soils collected from 14 different altitudes of Mt. Jianfengling contain abundant microbial fatty acids and fatty alcohols, including iso / anteiso fatty acids (i / aC12: 0-i / aC19: 0), 10-Me- C16: 0 fatty acid and iso / anteiso fatty alcohols unsaturated fatty alcohols, which can be a strong microbial activity in the Jianfengling soils. The branched and unsaturated fatty alcohols can be only only detected when the saponification is performed, implying that these lipids are present as the constituents of bacterial wax esters in the soils. of aC15 / iC15 fatty acids is positively correlated with altitude, suggesting that the decrease in temperature can induce the increase in the relative abundance of anteiso C15 fatty acid. In contrast, the ratio of aC15 / iC15 fatty alcohols and of aC15 / n C15 fatty alcohols both decrease with increased altitude or decreased temperature. Similarly, the ratio of nC18: 1 / nC18: 0 fatty alcohols also decreases with decreased temperature, which is opposite to the previous observations that unsaturation of fatty acids in microorganism increases in response to decreased temperature.Besides, the average chain length (ACL) of long chain fatty alcohols (C22-C30) from leaf waxes and carbon preference index (CPI) of all n-fatty alcohols are also significantly correlated with altitude or mean annual temperature, demonstrating their potential for paleoclimate reconstruction. The correlation of microbial fatty acids and alcohols as well as ACL and CPI of plant wax-derived fatty alcohols with altitude may provide novel ways to reconstruct paleotemperature and paleoaltimetry.