Pollen- and charcoal-based evidence for climatic and human impact on
vegetation in the northern edge of Wuyi Mountains, China, during the last 8200
years
Pollen and charcoal records derived from the sediment core of Lantianyan (LTY)
peat bog, Northern Wuyi Mountain chains, eastern subtropical China, provide
valuable information of landscape evolution caused by both climatic variation
and anthropogenic activities over the past 8200 years. Our results reveal
fluvial and lacustrine deposition between c. 8200 and 5600 cal. yr BP. The
high proportion of pollen from evergreen broadleaved forests (e.g. Quercus and
Castanopsis) and Alnus trees, a taxon frequently occurring in mountain
wetlands, implies a humid interval, which is consistent with the Holocene
moisture maximum in eastern China. After 5600 cal. yr BP, the spread of the
wooded swamp taxon, Glyptostrobus, suggests shallow water conditions and peat
formation caused by gradual drying. The drying trend generally corresponds
with the speleothem isotope record from this region, revealing a weakening
East Asian summer monsoon (EASM) due to a decrease in Northern Hemisphere
summer insolation (and in air temperature). Peaks in the abundance and
concentration of Glyptostrobus pollen at c. 4600–4400 cal. yr BP and c.
3300–3000 cal. yr BP suggest two periods of swamp expansions, which coincide
with the drought intervals revealed by the speleothem records. The LTY pollen
and charcoal record demonstrates that human-induced land cover change was
negligible before 3600 cal. yr BP. We consider the first signal of intensive
human activity and landscape clearing to be the noticeable increase in
charcoal particles at around 3600 cal. yr BP. This anthropogenic impact is
followed by a dramatic decrease in arboreal pollen and increase in Poaceae
pollen percentages, likely reflecting a transition to rice-paddy agriculture
in the study area