East Asian summer monsoon changes in subtropical China since late Pleistocene: Evidence from the Ailuropoda-Stegodon fauna.

Previous studies on the amplitude of East Asian summer monsoon (EASM) changes mainly focused on northern China (represented by the Loess Plateau). However, a rare investigation centered on the subtropical zone of southern China, where the important route for EASM moved northward or southward, especially addressing a lack of the research on mammals. The Ailuropoda-Stegodon fauna is a representative mammal fauna in southern China since the late Pleistocene. It indicates the southern mid-subtropical-tropical forest environment with tropical climate characteristics, and its southward or northward movements in the subtropical zone imply the changes of EASM intensity. Based on previous research, combined with the species characteristics and distribution range of the Ailuropoda-Stegodon fauna with tropical animals during the marine isotope stage 5 (MIS5), MIS3, MIS2, and MIS1 Megathermal periods, this paper mainly investigates its evolution and the fluctuations of EASM. The conclusions include: (1) The distribution geometric centers in the MIS5, MIS3, MIS2, and MIS1 Megathermal periods are (26°14′N, 111°22′E), (24°35′N, 107°30′E), (22°48′N, 112°01′E), and (26°19′N, 112°25′E), respectively. (2) Compared with the MIS5 period, the EASM of the MIS3 and MIS2 moved 180 km and 380 km southwards, and that of the MIS1 Megathermal period moved about 10 km northwards. The EASM movement indicated by the fauna migration happened synchronous with the climate records of stalagmites in subtropical China, the sporopollen from eastern China, and oxygen isotopes from Sulu Sea. They also correspond to the peaks and valleys of the total solar radiation at 35°N in the winter half-year. This suggests that the migrations of the Ailuropoda-Stegodon fauna are consistent with the changes of the global climate, and the driving force is mainly from the changes of total solar radiation at 35°N in the winter half-year. [ABSTRACT FROM AUTHOR]