Spatiotemporal changes in C4 plant abundance in China since the Last Glacial Maximum and their driving factors

Abstract

Knowledge of changes in the distribution of C3 and C4 plants in relation to climate change is the key to predicting the biosphere's response to future climatic warming. There are significant differences in the spatiotemporal evolution of C4 plant abundance at different latitudes since the Last Glacial Maximum (LGM), and the factors responsible remain debated. In this study, we reconstructed the spatiotemporal pattern of C4 plants in China since the LGM, based on a synthesis of δ13C records of soil organic matter from paleosol sequences and δ13C records of individual n-alkanes from lake and marine sediments. The results indicate that, spatially, maximum C4 abundance during the LGM was in South China; while maximum C4 abundance occurred in the Chinese Loess Plateau in North China during the early and mid-Holocene. Temporally, in North China, C4 plant abundance initially increased since the LGM, reached a maximum during the early and mid-Holocene and then decreased; however, the opposite trend occurred in South China. Combined with a physiological-process model used to study the sensitivity of C3 and C4 plants to changes in climate and atmospheric pCO2 in different regions, our results reveal that temperature was the dominant factor driving C4 plant expansion in North China, whereas atmospheric pCO2 and precipitation were the main factors controlling C4 plant abundance in South China.