A last glacial and deglacial pollen record from the northern South China Sea: New insight into coastal-shelf paleoenvironment

Morphological diversity of Quercus fossil pollen in the northern South China Sea during the last glacial maximum and its paleoclimatic implication

“…Although subgenera Quercus and Cyclobalanopsis are not structural species of the forests, their pollen has a good representation, comprising 20%–40% of the pollen count in the montane rainforest on Hainan Island [ 34 ]. Subgenus Quercus (including subgenus Cyclobalanopsis ) was a dominant broadleaved component (~20%) in the northern SCS; its pollen was derived from south Mainland China or the exposed continental shelf [ 8 , 35 ]. Because structural species such as Lauraceae have low pollen representation, the high presence of Quercus pollen (mainly subgenera Cyclobalanopsis type) is a good indicator of subtropical forests [ 11 ].…”

“…In several pollen records located in the northern SCS, non-arboreal pollen dominated during the LGM [ 1 – 2 , 6 , 8 ]; such pollen types were probably derived from the exposed continental shelf. However, the co-existence of rich subgenus Cyclobalanopsis (including subgenus Quercus ) and non-arboreal plants is impossible, which is because the former indicates dense forests and the latter originates in grassland or steppe environment, a combination of environments that has no comparable analogue in the current vegetation cover.…”

“…Until now, many palynological studies sought to reveal paleoclimatic conditions during the last glaciation in the northern SCS using drilling cores ODP 1144, SO 17940, MD05-2904, MD05-2906, and STD 235 [ 1 – 3 , 6 , 8 , 10 ] and the lacustrine pollen documents from the Leizhou Peninsula [ 7 , 36 ], Chaoshan Plain [ 12 ], and Huguangyan Maar Lake [ 13 ] in mainland China and the island of Taiwan [ 4 ]. Based on those palynological records, different interpretations have been proposed.…”

“…Various climate interpretations based on pollen data have been proposed in previous studies for the inland of the northern SCS during the LGM, from temperate climate [ 1 – 3 ] to middle subtropical and southern subtropical climate [ 4 – 8 ]. Such debatable interpretations may be attributed to the lack of reliable pollen proxy data (e.g., indicator of temperature).…”

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“…ESA underwent a tremendous biome turnover over the last glacial/ interglacial transition (Ni et al 2010). Today, the evergreen broad-leaved (EBL) biome prevails in ESA, and during the last glacial period it was dominated by a fragmented deciduous broad-leaved (DBL) vegetation (Yue et al 2012) over the mountain landscapes and open vegetation at lower altitudes (Yu et al 2017). The EBL biome (known as laurophyllous forest), currently the most widely distributed biome in eastern Asia, extends from about 22°N to 33°N under a monsoon regime.…”