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

Knowledge of changes in the distribution of C-3 and C-4 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 C-4 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 C-4 plants in China since the LGM, based on a synthesis of delta C-13 records of soil organic matter from paleosol sequences and delta C-13 records of individual n-alkanes from lake and marine sediments. The results indicate that, spatially, maximum C-4 abundance during the LGM was in South China; while maximum C-4 abundance occurred in the Chinese Loess Plateau in North China during the early and mid-Holocene. Temporally, in North China, C-4 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 C-3 and C-4 plants to changes in climate and atmospheric pCO(2) in different regions, our results reveal that temperature was the dominant factor driving C-4 plant expansion in North China, whereas atmospheric pCO(2) and precipitation were the main factors controlling C-4 plant abundance in South China.