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Abstract: Lipid biomarkers extracted from a peat core obtained from the northeast edge of the Tibetan Plateau have provided a 13 kyr record of regional climate change. A period of warmer climate corresponding to the Holocene Optimum between 9ka and 5ka is evident in greater alteration of n-alkanoic acids and n-alkanols and in the appearance of biomarkers indicative of greater microbial activity. Concomitant increases in local precipitation that raised the water level of the peat bog are recorded by increases in the proportions of C23 and C25 n-alkanes that are mainly derived from submerged/floating plants. Alternations in submergent and emergent plant n-alkane proxies reveal multi-decimeter scale rises and falls in the bog water level that relate to variation in precipitation on the Tibetan Plateau during the Holocene. Major low water level events occurred around 12.6, 11.3, 10.7, 9.4, 8.3, 6.0, 4.5, 3.1, 2.1 and 1.0ka. These events correlate well with cold dry events recorded in same region from other climatic proxies that reflect millennial-scale Holocene instability in the Asian monsoon system. Our biomarker results also indicate that peat accumulation and preservation on the Tibetan Plateau are more sensitive to variability in monsoonal precipitation than in annual temperature. [Copyright &y& Elsevier]

• Warm-dry and cold-wet hydroclimate modes were showed according to 18,000-year temperature and DWT changes in Dajiuhu Basin. • Peatland ecology sensitively responded to palaeo-hydroclimatic changes. • More bulliform phytoliths induced by exaggerated plant leaf water loss occurred during warm-dry mid-Holocene. • Plant water regulation, climate, and irradiance showed a synchronous ~1000-yr cycle. Peatland ecosystem processes are strongly influenced by hydrology linked to climate change. However, how transpiration, as major water loss pathway in closed peatland, responds to climate change and then regulates ecosystem water balance that remains poorly understood. Here, we reported an 18,000-year fossil phytolith record from an herbaceous community-dominated mountain peatland in central China to reconstruct climate changes and vegetation evolution and reveal the interactions between regional climate changes and peatland ecosystem. The abundance of bulliform phytoliths—a silicified type of cells that regulate the movements of plant leaves to reduce light exposure and transpiration rate—shows close correlations with the Holocene climate variations with higher bulliform abundance in response to warm-dry climate (11,500–9600 cal yr BP; 7500–3000 cal yr BP) and lower values associated with cold-wet climate (13,000–11,500 cal yr BP; 3000 cal yr BP-present). Spectral analysis reveals that bulliform abundance and reconstructed climate vary with a major ~1000-year periodicity during the Holocene, suggesting a possible causal relationship to solar activity. A high bulliform abundance and warm-dry climate correspond with enhanced solar activity, and vice versa. We interpret that the resultant leaf water deficit resulted from greater light interception, high temperature and drought promoted the production of bulliform cells to fold leaf for water conservation, which is an effective protective mechanism of peatland grasses from the environmental stress. These results expand our understanding of how grass-dominated peatland plant water regulation recorded by bulliform phytoliths responds to solar radiation and local hydroclimate during geological period. [ABSTRACT FROM AUTHOR]