Early Oligocene vegetation and climate of southwestern China inferred from palynology

The early Oligocene represents the beginning of the modern icehouse world. To better understand how vegetation and climate changed during this period, we reconstruct quantitively the early Oligocene vegetation and climate by analyzing fossil spore and pollen assemblages from Lühe basin, Yunnan Province, in southwestern China. The reconstructed paleoclimate using Bioclimatic Analysis shows that the mean annual temperature (MAT) ranged from 14.4 to 15.4 °C, the mean annual precipitation (MAP) was 1070.1–1297.8 mm, and the range of mean temperature of coldest quarter (MTCQ) was 6.7 to 7 °C, lower than that of the present day (9.3 °C). The reconstructed regional vegetation indicates a deciduous broadleaved forest mixed with evergreen broadleaved elements. Considering other Paleogene floras in Yunnan, deciduous broadleaved elements dominated in this area from the late Eocene to the early Oligocene. The paleoclimate reconstruction suggests that this vegetation composition may have been controlled mainly by cold winter temperatures.