Quantifying regional vegetation changes in China during three contrasting temperature intervals since the last glacial maximum

The need to reduce the uncertainty of predictions of vegetation change under global warming highlights the importance of understanding the vegetation patterns and possible mechanisms of vegetation response during past warming intervals. Here, we present quantitative regional vegetation reconstructions for China during the Last Glacial Maximum (LGM, 18 +/- 2 C-14 kyr B.P.), early Holocene (EH, 8.5 +/- 0.5 C-14 kyr B.P.), and mid Holocene (MH, 6 +/- 0.5 C-14 kyr B.P.), using the biomization method and based on 249 pollen records. In addition, we used an inverse vegetation modeling approach to investigate the effect of climate change and CO2 concentration on the observed vegetation changes. The results demonstrate that during the LGM, steppe expanded southeastwards, reaching the present-day temperate deciduous forest (TEDE) zone; in contrast, the forest in eastern China underwent a substantial southward retreat and its percentage reached a minimum. The warm mixed forest (WAMF) and TEDE shifted southwards of similar to 10 degrees N relative to today, and tropical seasonal rain forest (TSFO) was almost absent. In addition, the forest-steppe boundary shifted southwards to near the middle and lower reaches of the Yangtze River. During the EH and MH, the TSFO, WAMF, and TEDE exhibited respective northward shifts of 2 degrees, 4 degrees and 5 degrees relative to today. In MH, the percentage of forest sites increased and reached a maximum, and the forest-steppe boundary had shifted northwestwards to near the present-day 300 mm isohyet. Our palaeovegetation reconstructions and model sensitivity experiments suggest that temperature was the dominant factor controlling the vegetation distribution during the LGM, while precipitation became increasingly more important during the Holocene throughout China. We further show that precipitation was the primary factor controlling palaeovegetation distribution in northern China, while temperature became increasingly more important in southern China. Our findings are potentially important for understanding the evolution of vegetation in China in response to ongoing global warming