Evolution of the relative abundance of C4 plants on the Chinese Loess Plateau since the Last Glacial Maximum and its implications

Abstract

ABSTRACTUnderstanding the distribution of C3 and C4 plants and its forcing mechanisms since the Last Glacial Maximum (LGM) is important for anticipating their possible response to future climate change. The spatiotemporal pattern of C4 plant abundance on the Chinese Loess Plateau (CLP) is complex and the dominant causal factors are contentious. Here, we use δ13C records of organic matter in paleosols from the CLP to reconstruct changes in the representation of C4 plants since the LGM. The results indicate that the relative abundance of C4 plants increased after the LGM, reaching a maximum during 10–6 ka bp, and then decreased. Spatially, the representation of C4 plants was characterized by increasing values from north‐west to south‐east. In addition, the smallest spatial difference (∼10%) in the representation of C4 plants between the north‐west and south‐east parts of the CLP was during the LGM, and the largest difference (∼30%) was during the early Holocene. We combined our findings with output from the BIOME4 model to study the sensitivity of C4 plants to changes in climate and atmospheric CO2 concentration. The results suggest that increasing temperature was the dominant factor driving C4 plant expansion on the CLP since the LGM.