Millennial-scale vegetation changes during the last 40,000 yr based on a pollen record from Lake Biwa, Japan

Abstract

A high-resolution pollen record covering the last 40,000 yr (BIW95-4) from Lake Biwa, western Japan, shows regional vegetation responses to millennial-scale climate changes. From 40 to 30 ka,Cryptomeria japonicawas dominant around the lake among pinaceous conifers and deciduous broad-leaved trees. During this period, fluctuations ofC. japonicaare correlated with Dansgaard–Oeschger (D–O) cycles recognized from the anhysteretic remanent magnetization (ARM) record. Increases in the abundance of this taxon may have been caused by wetter summer conditions influenced by the East Asian monsoon or increased snowfall on the Sea of Japan side of the Japanese archipelago. Between 29 and 14 ka, pinaceous conifer forests mainly composed ofPinussubgenusHaploxylon,Tsuga, andPiceatrees developed. At approximately 23 ka,Piceatrees increased in abundance as ARM values decreased. This expansion ofPiceatrees has been correlated with Heinrich event (HE) 2 in the North Atlantic. At about 14 ka, the distribution of broad-leaved forest (mainly composed of deciduous oaks) began to expand after D–O 1. Evidence of significant vegetation change related to the abrupt Younger Dryas cooling event has not been found.

Asian monsoon climate during the Last Glacial Maximum: palaeo‐data–model comparisons

“…Reconstructed precipitation from sites around 30°N (#35, Wang et al 2001;#36, Zhou et al 2008;#34, Cosford et al 2010) also imply a change between c. 20 and c. 19 ka BP, but in the opposite direction, i.e. Pollen records from Japan show either low P-E throughout the LGM (#40, Hayashi et al 2010), or relatively wet climatic conditions c. 22.5 ka BP, which were followed by a drier climate until 19 ka BP and again wetter conditions thereafter (#42, Yasuda 1982). Reconstructed and modelled position of the ITCZ Proxy-based reconstructions of LGM climatic conditions can be compared to precipitation calculated from CCSM3 output data according to the method outlined by Braconnot et al (2007) to provide insight into the geographical extent of the summer monsoon, i.e. Pollen records from Japan show either low P-E throughout the LGM (#40, Hayashi et al 2010), or relatively wet climatic conditions c. 22.5 ka BP, which were followed by a drier climate until 19 ka BP and again wetter conditions thereafter (#42, Yasuda 1982). Reconstructed and modelled position of the ITCZ Proxy-based reconstructions of LGM climatic conditions can be compared to precipitation calculated from CCSM3 output data according to the method outlined by Braconnot et al (2007) to provide insight into the geographical extent of the summer monsoon, i.e.…”

Two modes of climatic control in the Holocene stalagmite record from the Japan Sea side of the Japanese islands

“…High‐resolution pollen analysis in Lake Biwa shows a gradual replacement of deciduous oaks by temperate conifers ( Cryptomeria japonica ) during the early Holocene (Hayashi et al . ). A comparable result is the pollen analysis at Lake Mikata on the Japan Sea side, which indicated the establishment of warm–temperate lucidophyllous forests at around 7.3 ka (uncalibrated 14 C age of 6300 yr BP) (Takahara & Takeoka ).…”

Assessment of hydrogen isotopic compositions of n‐fatty acids as paleoclimate proxies in Lake Biwa sediments

“… Comparison of pollen records in Lake Biwa sediment cores (cores BIW95‐4 and Takashima‐oki) (Hayashi et al , 2010a, 2010b) with the δ D of n ‐C 28 FA in the Lake Biwa 200 m sediment core. (a) δ D of n ‐C 28 FA in the Lake Biwa 200 m sediment core.…”

“…According to sedimentary pollen records in Lake Biwa (BIW95‐4) and Takashima‐oki (Fig. 4), trees dominated over herbs in warm periods such as the Holocene, MIS 3 and MIS 5, whereas herbs expanded during cold periods such as MIS 2, MIS 4 and MIS 6 (Hayashi et al , 2010a, 2010b). However, the temporal variability of C 28 n ‐FA δ D is different from the tree/herb pollen ratio in most periods except for MIS 2.…”