Sprecher
Beschreibung
Quercus subgenus Cerris is one of the two subgenera in Quercus, with around 140 species in the sections Ilex, Cerris and Cyclobalanopsis. The sects. Ilex and Cyclobalanopsis are mostly evergreen, while the sect. Cerris is almost deciduous. They prefers to different ecological habitats, climate and geographical ranges, providing palynologists a key to reconstruct vegetation and associated climate using pollen. However, classifying subgenus Cerris pollen is challenging due to overlaps in pollen size, sculpture and aperture under LM or even SEM. This study focuses on aperture and sculpture of three sections of the subgenus Cerris to refine diagnostic keys.
Pollen sculpture patterns under LM between the sects. Cyclobalanopsis and Ilex are very similar, but can be largely distinguished under SEM according to aggregated granular with the sect. Cyclobalanopsis and rod-like/rugulate elements with the sect. Ilex. The sect. Cyclobalanopsis contains about 90 species native to tropical and subtropical Asia, thus their fossil pollen can be practically indicative warm and humid climate associated with Eastern Asian Monsoon, while pollen of mountain oaks in western alpine areas of China can be an indicator of cold and seasonal dry climate. Pollen sculpture of the sect. Cerris shows scattered verrucate, and its pollen type is tricolpate, thus safely to be distinguished from the sects. Cyclobalanopsis and Ilex (mostly tricolporoidate-tricolporate). To improve paleoecological interpretation, SEM-aided identification and calibration are effectively used in classifying subgenus Cerris pollen types into different sections in western China’s alpine lakes, and improved vegetation and climate reconstruction, spanning LGM to late Holocene.