Papers by Toshiyuki Fujiki
A new modern analogue reference dataset and its application to the 430-kyr pollen record from Lake Biwa, supplement to: Tarasov, Pavel E; Nakagawa, Takeshi; Demske, Dieter; Österle, Hermann; Igarashi, Yaeko; Kitagawa, Junko; Mokhova, Lyudmila M; Bazarova, Valentina B; Okuda, Masaaki; Gotanda, Kat... This study presents a newly compiled dataset of modern pollen and climate data from 798 sites acr... more This study presents a newly compiled dataset of modern pollen and climate data from 798 sites across Japan and the Russian Far East. This comprehensive reference dataset combined with the modern analogue technique (MAT) provides a powerful tool for pollen-based reconstruction of the Quaternary Northwest Pacific climate. Pollen-derived reconstruction of the modern climate at the reference pollen-sampling sites matches well with the estimated modern climate values (R2 values vary between 0.79 and 0.95, and RMSEP values vary between 5.8 and 9.7% of the modern climatic range for all nine tested variables). The successful testing of the method encourages its application to the fossil pollen records. We used a coarse-resolution pollen record from Lake Biwa to reconstruct glacial-interglacial climate dynamics in central Japan since ~438 kyr and compared it to the earlier reconstruction based on a less representative reference dataset. The current and earlier results consistently demonstrat...
Since the middle Holocene, peaty layers have accumulated on the Kimotsuki lowland in south Kyushu... more Since the middle Holocene, peaty layers have accumulated on the Kimotsuki lowland in south Kyushu, Japan. They can be applied radiocarbon (ˆ {14} C) wiggle-matching for establishing high-resolution chronology. Moreover, several tephra intercalated with the peat bed which originated from Kaimondake, Sakurajima, and the Kirishima volcanoes, and they can certify the reproducibility of C dates. On the other hand, the age of the tephra by them can be determined correctly. We present here the results of AMS C dating on the core sample, and report the age of each tephra determined from these dates.
A 9.5-m sediment core was obtained from site IrBH-1 in Juban, Sorsogon, located north of the Iros... more A 9.5-m sediment core was obtained from site IrBH-1 in Juban, Sorsogon, located north of the Irosin caldera, southern Luzon, Philippines. Systematic meter-scale logging and documentation were performed to describe and interpret the sedimentary stratigraphy. The core sediments were divided into three layers based on sedimentary facies: (1) Layer A (surface to 3.0 m depth) consists of a mixture of pumice and lithic fragments in a silty matrix. It is composed of a brownish layer with a silty matrix containing coarse and fine pumice grains. (2) Layer B (3.0 to 6.3 m depth) consists of a mixture of pumice and lithic fragments in a silty matrix. The pumice grains contain phenocrysts of cummingtonite, which is an important key mineral. (3) Layer C (6.3 to 9.5 m depth) contains dense volcanic rocks ranging in size from pebbles to boulders.
Radiocarbon, 2018
ABSTRACTWe collected peat sediments (sediment core ADK13083002) from Haven Lake on the north side... more ABSTRACTWe collected peat sediments (sediment core ADK13083002) from Haven Lake on the north side of Adak Island (central Aleutian Islands, Alaska) to determine whether the vegetation has changed. We confirmed the presence of six tephra layers, including Forty Years (0.3 cal ka BP), T2, YBO (3.3 cal ka BP), Intermediate (6.4 cal ka BP), Main (9.5 cal ka BP), and T6. We identified four major pollen assemblage zones (HL-1 to HL-4, in descending order) in the cored sediment. HL-1 was dominated by Ranunculaceae and Empetrum pollen; H-2 was dominated by Poaceae, Ranunculaceae, and Empetrum pollen; HL-3 was dominated by Poaceae and Empetrum pollen; and HL-4 was dominated by Poaceae, Cyperaceae, Lycopodiaceae, and Empetrum pollen. Small charcoal particles, likely transported from a distance, were found at low frequencies until 6.4 cal ka BP. The total cross-sectional area of charcoal particles increased to 1500 μm2 or more by 6.4 cal ka BP, implying that the large charcoal particles origin...
Advances in Asian Human-Environmental Research, 2012
Open image in new window Reconstruction of the paleoclimate based on analyses of annually laminat... more Open image in new window Reconstruction of the paleoclimate based on analyses of annually laminated sediments in Japan and moat sediments from Angkor Thom in Cambodia indicates that there had been a period of drastic cooling during AD 1430–1500 accompanied by a weakening of monsoon activity. The annual mean temperatures show that—compared to the peak of medieval warm epoch around AD 1150—the mean temperature dropped by nearly 5°C in AD 1430. The climatic cooling brought about the weakening of the summer monsoon, which in turn would have resulted in the delayed arrival of the wet season. This might have had a catastrophic impact on rice cultivation in Cambodia leading to the decline of the Khmer Civilization.
Ice core studies from middle and low latitude glaciers have a problem that a reliable dating meth... more Ice core studies from middle and low latitude glaciers have a problem that a reliable dating method has proved difficult due to wind erosion and vanishingly small amount of seasonal precipitation. They obscure the annual signal from the seasonal variations in chemical concentrations and oxygen isotope ratios that are typically used to date for ice cores. On the other hand, the ice cores from alpine glaciers contain many species of pollen grains that have different pollen seasons. Here we show that these pollen peaks allow us to decide four seasonal layers of a snow pit, and examine whether some seasonal missing layers due to wind erosion or little seasonal precipitation exist. In addition, they accordingly allow us to give an accurate measure of annual snow deposition even from the glacier where some seasonal layers are eroded by wind, or missing due to little seasonal precipitation.
Kikan Chirigaku, 1998
Kashira Island is situated in the Inland Sea, near Hinase town, Okayama Prefecture. The 44-m core... more Kashira Island is situated in the Inland Sea, near Hinase town, Okayama Prefecture. The 44-m core consisted of clay, sandy clay, gravel with sand, humus and tephra (Aira: 2,540-2,390cm depth, Akahoya: 1,900-1,890cm depth). The humus portion (2,368-2,360 cm depth) was dated to 21,100+400 yr B.P. by the 14C-dating method. Pollen analysis revealed the core to consist of nine pollen and two barren zones. Layers containing Lagerstroemia pollen, the important index taxa for the warm period, were regarded as sediments of the warm period. This core may contain the sediments of four warm (KS 9, 8, 6, 4-1) and three cold periods (KS 7, 5 and BZ-2, 1). KS-4-1 represent the post glacial period.
Advances in Asian Human-Environmental Research, 2012
Open image in new window A pollen analysis of the Angkor Thom moat deposits was conducted to dete... more Open image in new window A pollen analysis of the Angkor Thom moat deposits was conducted to determine the environmental background of the growth and decline of the Khmer dynasty. The horizon of vegetation change was discovered at approximately 155 cm depth, at which there was a decrease in tree pollen grains accompanied by a rapid increase in herb pollen grains. The age of this sediment is from 645 ± 30 BP to 640 ± 30 BP, and this vegetation change corresponds to the peak of the Khmer dynasty. Furthermore, it was revealed that Poaceae plants changed from a wild species to a cultivated species based on morphological studies of Poaceae pollen. It is believed that paddy fields expanded around Angkor archaeological sites and the with harvested rice were then brought into the capital city of the Khmer Empire.
This paper presents morphology of pollen grains of four European Sorbus species: S. arranensis He... more This paper presents morphology of pollen grains of four European Sorbus species: S. arranensis Hedl., S. aucuparia L., S. hybrida L., S. mougeotti Soy.-Will. & Godr. The impor- tance of exine sculpture details in taxonomy is underlined.
Vegetation History and Archaeobotany, 2004
Human activity and climate change during the historical period in central upland Japan with refer... more Human activity and climate change during the historical period in central upland Japan with reference to forest dynamics and the cultivation of Japanese horse chestnut (Aesculus turbinata)
Review of Palaeobotany and Palynology, 2012
Illustrations of, and keys to, mangrove pollen and spores from extant taxa are essential to studi... more Illustrations of, and keys to, mangrove pollen and spores from extant taxa are essential to studies of tropical Quaternary palynology and palaeoecology of estuarine and marine deposits. In this paper we present a pollen morphological "atlas" and identification keys for most of the mangrove flora of the coastal areas of south China, including an interspecific key to the major mangrove elements Rhizophora and Sonneratia. The morphology of the pollen and spores of 38 species of living mangrove and associated plants is described and illustrated by transmitted light photographs and scanning electron micrographs. These descriptions and illustrations, and the identification keys are presented at an achievable taxonomic level. The keys are open for future development so that pollen of other mangrove and associated plants can be accommodated when available. In their present state they should, nevertheless, aid palynological analyses of Quaternary mangrove and associated estuarine and marine deposits, particularly in the South China Sea and surrounding regions, but also elsewhere in tropical and subtropical regions.
Radiocarbon, 2014
This study presents accelerator mass spectrometry (AMS) radiocarbon dates and pollen assemblages ... more This study presents accelerator mass spectrometry (AMS) radiocarbon dates and pollen assemblages of 400-cm core sediments collected from the Karekare Swamp in Rarotonga, Southern Cook Islands, to investigate vegetation changes on the island, in particular those induced by human impacts. Eight 14C dates of charcoal and higher plant fragment samples indicate that the sediments accumulated since ∼6.0 cal kBP, with an apparent interruption of deposition (hiatus) from 130 to 132 cm in depth, corresponding to ∼2.8 to 0.7 cal kBP. The appearance of Chenopodiaceae pollen from upland weeds, and Cucurbitaceae and Vigna pollen grains from cultivated plants suggest that human influence existed in core sediments above 130 cm in depth. The increased abundance of Pandanus pollen and monolate-type fern spores also implies the existence of human activity.
Radiocarbon, 2013
We performed pollen analysis and accelerator mass spectrometry (AMS) radiocarbon dating on cored ... more We performed pollen analysis and accelerator mass spectrometry (AMS) radiocarbon dating on cored sediments (KS0412-3) from Kashibaru Marsh, located in the western part of the Sefuri Mountains in northern Kyushu, southwestern Japan, to investigate environmental change around the marsh. Sediment accumulation began in this marsh around cal AD 1200 and continued with an estimated average sedimentation rate of about 4 mm/yr. Human rice cultivation at this location began around cal AD 1300 and was abandoned due to the deposition of a thick sand layer at around cal AD 1400. Since this event, the area has been maintained as a "natural" marsh.
Quaternary Science Reviews, 2011
C 3 and C 4 plants d 13 C of TOC East Asian monsoon Holocene Korea ENSO activity Sea surface temp... more C 3 and C 4 plants d 13 C of TOC East Asian monsoon Holocene Korea ENSO activity Sea surface temperature a b s t r a c t At centennial to millennial timescales, little is known of C 3 and C 4 plant productivity's responses to past regional climate changes and the dominant forcing factors during the Holocene, although large-scale changes in glacial-interglacial periods have been attributed to changes in aridity, temperature, and CO 2 concentration. We investigated the d 13 C of TOC, C/N ratios, and pollen in samples from a wetland on Jeju Island, Korea. The bulk isotopic signal ranging from À17& to À29& was partitioned into C 3 and C 4 plant signals by using a binary mixing model and calculating separate organic carbon-accumulation rates for C 3 and C 4 plants (OCAR 3 and OCAR 4) during the last 6500 years. Pollen data indicated that the temperate deciduous broadleaved trees replaced grassland dominated by Artemisia, dry-tolerant grass, and further expanded in the maar. The long-term decreasing trend of Artemisia-dominated grassland was similar to those of d 13 C values and OCAR 4. The multi-centennial to millennial variability superimposed on the gradual increasing trend of OCAR 3 was inversely correlated with those of the sea surface temperature (SST) in the western tropical Pacific (WTP) and El Niño-Southern Oscillation (ENSO) activity, suggesting that C 3 plants have stronger sensitivity to regional climate change driven by oceanic forcing. Our data suggest that vegetation changes in a coastal area in East Asia were affected by monsoonal changes coupled with SST in WTP and ENSO activity. The vegetation change on Jeju Island varied quite differently from change in the westerly pathway, suggesting only a weak influence from high-latitude-driven atmospheric circulation changes. We conclude that centennial-to millennial-scale climate changes in coastal regions of East Asia during the mid-to late-Holocene may have been mainly controlled by lowlatitudinal oceanic forcing, including forcing by SST and ENSO activity.
Quaternary International, 2004
Quaternary International, 2004
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Papers by Toshiyuki Fujiki