PP21B-2244
C4 plant expansion since the late Miocene and the evolution of Asian summer monsoon
Tuesday, 15 December 2015
Poster Hall (Moscone South)
Haibin Wu1, Zhengtang Guo1, Joel Guiot2, Yanyan Yu1, Junyi Ge3, Yan Zhang1 and Shunzheng Peng4, (1)Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China, (2)CEREGE, Aix-en-Provence Cedex, France, (3)Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China, (4)Department of Tourism and Resources-Environment, Taishan University, Taian, China
Abstract:
A dramatic expansion of C4 plant distribution occurred in the South Asia during the late Miocene and in the East Asia during the Pliocene period, with broad spatial and temporal variations. Although the event is well documented, whether subsequent expansions were caused by a decreased atmospheric CO2 concentration or climate change is a contentious issue. In this study, we used an improved inverse vegetation modeling approach that accounts for the physiological responses of C3 and C4 plants to quantitatively reconstruct the paleoclimate in the Siwalik of South Asia and in the Loess Plateau of East Asia, based on pollen and carbon isotope data. We also studied the sensitivity of the C3 and C4 plants to changes in the climate and the atmospheric CO2 concentration. We suggest that the expansion of the C4 plant distribution since the late Miocene was unlikely caused by reduced CO2 levels alone. The expansion may have been primarily triggered by regional aridification, and seasonal analysis revealed that this climate shift mainly attributed to the summer rainfall decrease. Our findings suggest that this abrupt ecological shift mainly resulted from the weakening of the Asian summer monsoon, which may related to the decrease of SST in the tropic since the late Miocene.
