ラグナNo15.indb

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ひろきいそみ
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1 LAGUNA LAGUNA 15 p Pollen assemblage changes in the Holocene in the area of Izumo Plain Lake Shinji examples from Lake Shinji and Lake Jinzai Sayuri Kawai 1 Abstract: The vegetation and climate history since the early Holocene in the eastern Shimane Prefecture were clarified by pollen analysis performed on the two sediment cores drilled from Lake Shinji and Lake Jinzai. About 9500 cal.yrbp, the cool-temperate deciduous broad-leaved forest of Fagus and Quercus subgen. Lepidobalanus were dominated around Lake Shinji, the warm-temperate evergreen broad-leaved forests of Quercus subgen. Cyclobalanopsis and Castanopsis-Pasania were mixed with the cool-temperate forest around Lake Jinzai. Until about 7000 cal.yrbp, the warm-temperate forest predominated around this region because of warming. Until about 4300 cal.yrbp at Lake Shinji and about 3200 cal.yrbp at Lake Jinzai, the coastal forest of Pinus thunbergii grew on the sands appeared by regression, but the succession of warm-temperate forest progressed in spite of cooling. Then, Cryptomeria and Fagus were increased by the cooling. Until AD1635, secondary forests of Pinus densifolia were expanded by artificial effects. Key words: Holocene, pollen analysis, Lake Shinji, Lake Jinzai K-Ah cal.yrbp km K-Ah 8.2 ka Alley et al., C Institute of Mountain Science, Shinshu University, Asahi 3-1-1, Matsumoto , Japan. 1

2 1 SJ96 JZ01. Fig. 1. Location of the SJ96 Lake Shinji and JZ01 Lake Jinzai. 2 SJ96 JZ019500 cal.yrbp 14 C 1998 2004 1 79.1 km 2 47 km 4.5 m 1.35 km 2 5.3 km 1.

2 2 1 SJ96 JZ01. Fig. 1. Location of the SJ96 Lake Shinji and JZ01 Lake Jinzai. 2 SJ96 JZ cal.yrbp 14 C km 2 47 km 4.5 m 1.35 km km 1.1 m SJ N E m 23 m m m m m m m m m m 0.78 m. SJ96 IntCal04 Reimer et al., C m K-Ah cal yrbp m TOC TN TS JZ N E m, 24.3 m m m m m 1.1 m JZ01 IntCal04 Reimer et al., C

3 m K-Ah TOC TN TS C/N 2006 SJ96 JZ01 1 cm SJ96 10 cm JZ01 15 cm KOH ZnCl 2 HF SJ JZ Cupressaceae Platycarya Melia Sapium Buxus Rhus Aesculus Parthenocissus Camelia Elaeagunus Aucuba Cornus Ericaceae Symplocos Styrax Ligustrum Fraxinus Viburnum Lonicera Rumex Chenopodiaceae Caryopyllaceae Urticaria Ranunculus Thalictrum Sanguisorba Leguminosae Trapa Epilobium Haloragis Umbelliferae Nymphoides Labiatae Patrinia Campanulaceae Cichorioideae Carduoideae Typha Lilium SJ96 JZ01 SJ96 86 JZ01 95 SJ m m 2 SJ96 and/or SJ96 SJ m SJ m SJ SJ966.13m 5 5 SJ

4 2 SJ96 14 C 199820012006 Fig. 2. Lithology, 14 C dates, pollen diagram and local pollen zone at JZ01.

4 4 2 SJ96 14 C Fig. 2. Lithology, 14 C dates, pollen diagram and local pollen zone at JZ01. Columns and 14 C dates are based on Takayasu and the team for reconstruction of ancient environment in Izumo Province 1998, Takayasu 2001 and Yamada & Takayasu 2006.

5 SJ m 5 2 SJ SJ m 5 SJ SJ m 5 SJ SJ96 10 SJ m m m JZ01 JZ01 JZ m m JZ m JZ JZ m 10 5 JZ K-Ah JZ m JZ JZ m 3 JZ01 5

6 3 JZ01 14 C 2004 2006 2 Fig. 3. Lithology, 14 C dates, pollen diagram and local pollen zone at SJ96.

6 6 3 JZ01 14 C Fig. 3. Lithology, 14 C dates, pollen diagram and local pollen zone at SJ96. Columns and 14 C dates are based on Yamada et al and Yamada & Takayasu Legend of lithology is referred to Fig. 2.

7 JZ m 5 JZ JZ m 5 5 JZ JZ JZ mm m JZ01 10 SJ yrbp yrbp 2006 SJ cal.yrbp SJ cal.yrbp SJ cal.yrbp 7400 cal.yrbp SJ cal.yrbp

8 SJ cal.yrbp SJ JZ cal.yrbp 1990 JZ cal.yrbp JZ cal.yrbp JZ cal.yrbp 7300 cal.yrbp JZ cal.yrbp mm cal.yrbp 2006 JZ cal.yrbp JZ cal.yrbp JZ cal.yrbp cal.yrbp 1990 SJ m cal.yrbp JZ m cal.yrbp cal.yrbp 1990 SJ m cal.yrbp JZ m cal.yrbp 600

9 4 1990 2005 2006 Fig. 4. Relationship between pollen zone estimated by Onishi et al.,1990 and revised by Watanabe, 2005 in central Sanin district and pollen division in this study.

9 Fig. 4. Relationship between pollen zone estimated by Onishi et al.,1990 and revised by Watanabe, 2005 in central Sanin district and pollen division in this study. 14 C dates are based on Yamada and Takayasu cal.yrbp 1990 SJ m cal.yrbp 800 Tsuga sieboldii mm JZ01 JZ cal.yrbp 1990 SJ m cal.yrbp cal.yrbp cal.yrbp cal.yrbp 1990 SJ m cal.yrbp JZ m cal.yrbp 8.2 ka Alley et al., K-Ah cal.yrbp 2005 SJ m cal.yrbp JZ m cal.yrbp SJ96 JZ01

10 cal.yrbp 2005 SJ m cal.yrbp JZ m cal.yrbp JZ01 JZ cal.yrbp 2005 SJ m cal.yrbp JZ m cal.yrbp cal.yrbp SJ m cal.yrbp JZ m cal.yrbp SJ SJ m JZ m 1993 SJ m JZ m 1993SJ m JZ m 9500 cal.yrbp SJ96 JZ yrbp SJ cal.yrbp JZ cal. yrbp 2001 Alley, R.B., Mayewski, P.A., Sowers, T., Stuiver, M., Taylor, K.C. and Clark, P.U Holocene climatic instability: A prominent widespread event 8200 yr ago. Geology, 25: pp : pp Hopkins, J.S Differential flotation and deposition of coniferous and deciduous tree pollen. Ecology, 31: pp pp :

11 11 302pp : pp : LAGUNA 3: : : HB1 13: : pp Reimer, P.J., Baillie, M.G.L., Bard, E., Bayliss, A., Beck, J.W., Bertrand, C.J.H., Blackwell, P.G., Buck, C.E., Burr, G.S., Cutler, K.B., Damon, P.E., Edward, R.L., Fairbanks, R.G., Friedrich, M., Guilderson, T.P., Hogg, A.G., Hughen, K.A., KromerB., McCormac, G., Manning, S., Ramsey, C.B., Reimer, R.W., Rammele, S., Southon, J.R., Stuiver, M., Talamo, S., Taylor, F.W., van der Piichit, J. and Weyhenmeyer, C.E IntCal04 terrestrial radiocarbon age calibration, 0-26 cal kyr BP. Radiocarbon, 46: pp 1998 SJ96 LAGUNA 5: CT C N S LAGUNA 3: pp pp 2002 Cyclobalanopsis-Castanopsis 10: : : LAGUNA 11: : pp 1996 OH94 15: SJ96 Plate1. Pollen fossils from the SJ96 core. Scale bars are 10 m in length. 1 Pinus subgen. Diploxylon 7.85 m 2 Pinus subgen. Haploxylon m 3 Abies m 4 Picea m 5 Tsuga m 6 Podocarpus 7.32 m 7 Cryptomeria m 8 Myrica rubra 0.81 m 9 Myrica gale m 10 Betula m 11 Corylus 7.31 m 12 Cyperaceae m 13 Juglans-Pterocarya m 14 Carpinus-Ostrya m 15 Ulmus-Zelkova m 16 Fagus m 17 Salix m 18 Alnus m 19 Quercus subgen. Lepidobalanus m 20 Quercus subgen. Cyclobalanopsis 7.32 m 21 Castanea 7.32 m 20 m 22 Castanopsis-Pasania 7.85 m 23 Aphananthe-Celtis m 24 Lagerstroemia 9.51 m 25 Polygonum m 26 Carduoideae m 27 Artemisia m 28 Gramineae m

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.A...j....7(2)-.{.. 7 2 p. 47 58 1999 12 Jpn. J. Histor. Bot. * 6000 Masanobu Yoshikawa *: Vegetation Changes during the Last 6000 Years at the Tameike Site of the Musashino Upland, Central Kanto Plain Pollen influx 6000