Four peat humification-recorded Holocene hydroclimate changes in the southern Altai Mountains of China

Abstract

In this study, Holocene humification records were derived from four ombrotrophic peatlands to investigate the millennial-scale and decadal-centennial-scale variability of peat decomposition and to explore the paleoclimatic and paleohydrological implications. After eliminating the species-specific and site-specific noise and removing the time-dependency effect for each of four peat sequences, the averaged residuals of four peat humification sequences exhibit two-order variations. The millennial-scale variation of averaged residuals of four peat humification is characterized by a bow-shaped curve and is basically moisture-dependent. In detail, the humification in the middle Holocene (~8200–~4000 cal. yr BP) was higher than in the early Holocene (before ~8200 cal. yr BP) and also than in the late Holocene (after ~4000 cal. yr BP). The decadal/centennial-scale variations are superimposed on the bow-shaped curve and have been primarily paced by the sea surface temperature in the North Atlantic whose signals were propagated to Central Asia via the prevailing westerlies, which implies that lower temperature and lower temperature-suppressed evaporation (i.e. elevated moisture level) were most likely responsible for limiting the decomposition activity in the uppermost peat layer. These results indicate the potential for humification records from ombrotrophic peatlands in Central Asia to elucidate paleoclimate variability.