Pollen stratigraphy, vegetation and environment of the...

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Quaternary International 147 (2006) 16–33

Pollen stratigraphy, vegetation and environment of the last glacial andHolocene—A record from Toushe Basin, central Taiwan

Ping-Mei Liewa,�, Shu-Yue Huangb, Chao-Ming Kuoc

aDepartment of Geosciences, National Taiwan University, 1, Sec. 4, Roosevelt Rd. Taipei 106, Taiwan, ROCbDepartment of Life Science, National Taiwan University, 1, Sec. 4, Roosevelt Rd. Taipei 106, Taiwan, ROC

cChinese Petroleum Corporation, 3, Sung Ren Rd, Taipei 11010, Taiwan, ROC

Available online 9 November 2005

Abstract

The pollen record from the Toushe Basin (231490N; 1201530E; 650m above sea level), a peat bog of central Taiwan, displays a

continuous vegetation history of the past 96,000 yrBP of monsoon Asia. Instead of today’s closed subtropical evergreen broadleaved

forest dominated by Machilus–Castanopsis surrounding the basin, temperate deciduous forest predominated during most of the last

glacial. In early MIS 4, Alnus reaches the highest value of the whole sequence (60–70%) representing temperate deciduous forest and

relatively cold and arid conditions. Following this stadial, Alnus and herbs (mainly Cyperaceae) dominated alternately, with a minor

increase of Castanopsis. Peaks of monolete spores between cal. 42.2 and 37.0 kyr BP (kyr BP represent calibrated years) indicate episodic

wet conditions. The later glacial, especially between 23.2 and 18.7 kyrBP, shows a high percentage of Gramineae, indicating dry and

possibly sometimes cold conditions. The late glacial shows a remarkable increase of warm-temperate to temperate forest elements, such

as Ilex, Cyclobalanopsis and Symplocos. At about 15.1 kyrBP a peak of monolete spores indicates wet–warm conditions. A subsequent

sharp increase of Salix and then Gramineae between 13.0 and 11.6 kyr BP corresponds to the Younger Dryas. A warming event at

11.5 kyr BP is also evident. The Holocene is characterized by warm–wet conditions of the overwhelmingly abundant monolete spores

since 10.7 kyr BP and the prominent increase of Castanopsis.

r 2005 Elsevier Ltd and INQUA. All rights reserved.

1. Introduction

Toushe Basin (231490N; 1201530E; 650m above sea level),a 1.75 km2 desiccated peat bog in the low hills of centralTaiwan, is one of a series of north–south trending middlePleistocene tectonic basins along the island’s backbone(Fig. 1). To the north lies Sun-Moon Lake (or Jih-YuehTan, 750m above sea level) where a pollen sequencecovering time since the last glacial has been reported byTsukada (1967). Mountains surrounding these basins rangein altitude from 700m to higher than 1000m eastward. Thefluvial and lake deposits in Toushe Basin are about 80mthick. The bog became desiccated at about 1.8 kyr BP.

In the context of global climate, changes in low-latitudeareas have the same importance as those at high latitudes.Marine records of the last glacial from offshore Taiwanshow that low-latitude sea-surface temperature is not as

e front matter r 2005 Elsevier Ltd and INQUA. All rights re

aint.2005.09.003

ing author. Tel.: +886 2 33662932; fax: +886 2 23636095.

ess: [email protected] (P.-M. Liew).

warm (Huang et al., 1997) as previously estimated byCLIMAP (1981). This is also shown for other low-latitudeterrestrial areas (Flenley, 1979; Hooghiemstra, 1989;Farrera et al., 1999). On the other hand, a chronologicaldiscrepancy of climatic events between the two poles isrecognized (Sowers and Bender, 1995). Thus, the latitu-dinal variations of regional climates should be betterunderstood before attempting to interpret the globalfeatures of climate change, even though the climateconditions of higher latitude since the last glacial havebeen well documented. The tropical–subtropical record iscrucial in understanding the driving force of climate changefrom a global point of view (Stock, 1999). Recent studiesfrom the stalagmites of Hulu Cave (China) show that thetiming of changes in the monsoon generally agrees with thetiming of temperature changes from the Greenland ice coreGISP2 (Wang et al., 2001). This indicates that the EastAsian monsoon is integral to millennial-scale changes inatmosphere/oceanic circulation patterns and is affectedby orbitally induced insolation variations. Remarkable

served.

ARTICLE IN PRESS

Fig. 1. Location map of the studied site with the climate conditions of Sun-Moon Lake.

P.-M. Liew et al. / Quaternary International 147 (2006) 16–33 17

vegetation and climate changes during glacial time in thesubtropical island of Taiwan were found in a previousstudy of Sun-Moon Lake (Tsukada, 1967). According tohis study, by excluding Alnus pollen, an early stadial atsome time subsequent to 60,000–50,000BP contains pre-dominantly boreal conifers and pine and a low percentageof temperate elements, indicating a temperature decrease of8–11 1C; the period from about 50,000 to 10,000 BP isdominated by cool-temperate species. However, there areonly four radiocarbon dates in the core and a detailedrecord of climate change is not available. It is important toobtain a high-resolution pollen record with good agecontrol from the last glacial in Taiwan so as to reveal thesynchronism (or not) of global climate events. Thus, theToushe Basin was chosen for a study of its palynostrati-graphy. We use biomization of fossil pollen assemblages asproposed by Prentice et al. (1992, 1996) and used for thereconstruction of vegetation in Europe, Africa and Asia todiscuss the climatic conditions of the stadials andinterstadials of the last glacial and Holocene based onthe record of surface pollen assemblages of the naturalforests nearby in the Salixian area (Jolly et al., 1998;Tarasov et al., 1998; Yu et al., 1998; Allen et al., 2000;Takahara et al., 2000; Gotanda et al., 2002). We aim todescribe the vegetational changes quantitatively so asto interpret the magnitude of possible environmentalchanges. The simplified pollen diagram of the upper 17mof this site has been published previously (Liew et al., 1998;Kuo and Liew, 2000), but data to 39.5m depth will bedescribed here.

2. Modern vegetation and climate of the study area

Taiwan is a subtropical mountain island whose climate isdominated by the East Asian monsoon. Warm–wetsummers and cool-relatively dry winters prevail and the

whole island is generally humid. According to themeteorological data near the study site (Fig. 1), the Sun-Moon Lake Station (altitude 1014m) immediately north ofthe Toushe peat bog, mean annual rainfall is 2341mm,annual evaporation is 1098mm and mean annual tempera-ture is 19.2 1C. The coldest month has an averagetemperature of 13.9 1C, whereas the warmest month is23.6 1C, with an average of 155.6 rainy days. The estimatedmean annual temperature of Toushe is 21.2 1C, the lapserate being 0.54 1C/100m. The present vegetation surround-ing the study area belongs to the subtropical evergreenLauro-Fagaceae forest. This forest consists mainly ofMachilus kasanoi, M. zuihoensis, Beilschmiedia erythrofolia,Phoebe formosana, Sapium discolor, Michelia formosana,Cyclobalanopsis flauca, Pasania uraiana, P. konishii,P. ternaticupula, P. brebicaudata, Ardisia sieboldii, Zelkova

fomosana, Engelhardtia roxburghiana, Glochidion hongkon-

gensis, Trema orientalis, Liquidambar formosana, Rhus

succedanea, Schefflera octophylla, Castanopsis hystrix,Quercus variabilis, Fraxinus formosana, Lagerstroemia

subcostata, Symplocos theophrastaefolia and Sapindus

mukorosii among others (Lin et al., 1968).Tsukada (1967) described the vegetation of mountain

forests above the nearby subtropical forest as follows:

�
Warm-temperate forest (ca. 500–1800 m): Dominatedby Castanopsis, Lithocarpus, Cyclobalanopsis and Cin-
namomum with other broadleaved species and withconifers such as Keteleeria and Podocarpus species. Theundergrowth is crowded with ferns and mosses.
� Cool-temperate forest (ca. 1800–2400 m): Composed of
deciduous hardwood species of Cyclobalanopsis, Ulmus,Zelkova, Juglans, Carpinus and others, mixed withconifers including Chamaecyparis. Cyclobalanopsis andthe Chamaecyparis species form two separate associa-tions but both groups occupy the misty climate belt.

ARTICLE IN PRESSP.-M. Liew et al. / Quaternary International 147 (2006) 16–3318

�
Subalpine coniferous (or boreal) forest (ca. 2400–3500 m):Composed of Tsuga chinensis, Abies kawakami andPicea morrisonicola mixed with Pinus armandii. Aboveabout 3300m, alpine shrubs and herbs occur.
Su (1984) studied the vegetation in the mountains ofcentral Taiwan and identified the following altitudinalzones (Fig. 2) with annual temperature range:

(1)
Ficus–Machilus Zone (below altitude 500m; 23–26 1C;tropical): Lowland evergreen broadleaved forest in-cluding species of Ficus and Machilus.
(2)
Machilus–Castanopsis Zone (500–1500m; 17–23 1C;subtropical), submontane evergreen broadleaved forestwith two major types: 1. Castanopsis type: mainlycomposed of Castanopsis hystrix, C. Kawakamii,Schima superiba, Engelhardtia, Lithocarpus and 2.Machilus type: mainly Machilus japonica, M. kusanoi,Ficus, Lagerstroemia and tree fern species.
(3)
Lower Quercus Zone (1500–2000m; 14–17 1C; warmtemperate), with major components Cyclobalanopsis
longinus, C. gilva, Lithocarpus and Litsea species.
(4) Upper Quercus Zone (2000–2500m; 11–14 1C; tempe-
rate), with major components Cyclobalanopsis morii,

Fig. 2. Present vegetational zone in mountain ar

C. stenophylloides, Trochodendron and Castanopsis

carlesii.The Upper Quercus Zone is often mixed with montanemixed coniferous forest including Chamaecyparis,Pinaceae and Taxodiaceae, although they may separateinto associations. When local conditions are less humid,montane deciduous broadleaved forest appears inQuercus Zone including species of Acer, Juglans,Ulmus, Carpinus, Platycarya and Quercus. Whenaridity increases Alnus formosana prevails in this zonealthough this tree may appear at altitudes between 900and 2600m. However, Alnus with Salix, Carpinus andAcer frequently appear near 2000m, whereas Alnus

associated with Urticaceae usually occurs below thisaltitude. In addition, Pinus exists in the still drierconditions of this zone.

(5)
Tsuga–Picea Zone (2500–3100m; 8–11 1C; cool tempe-rate), with major components Tsuga chinensis, Picea
morrisonicola and Pinus armandii mastersiana.
(6) Abies Zone (3100–3600m; 5–8 1C; cold temperate),
mainly Abies kawakami. Beyond 3300m, alpine shrubsand herbs are scattered.

(7)
Alpine vegetation (43600m; o5 1C; cold), mainlyGramineae with some Juniperus.
ea, central Taiwan (after Su, 1984).

ARTICLE IN PRESSP.-M. Liew et al. / Quaternary International 147 (2006) 16–33 19

In an effort to elucidate the fossil sequence of Toushe, apreliminary study was made of the surface pollenassemblages of the natural forest in Salixian(231280–231330N; 1201530–1201590E), 30 km southeast ofthe Toushe site (Liew and Chung, 2001). This area includesthe Machilus–Castanopsis Zone, Lower and Upper Quercus

Zones and Picea–Tsuga Zone (Fig. 2) of Su (1984) betweenaltitudes 700 and 2800m (Chung, 1994). Pollen assem-blages above 2500m, the Picea–Tsuga Zone, are dominatedby Pinus, Tsuga and Picea. Below 2500m, in the Upper andLower Quercus Zones, pollen assemblages are morecomplex. Between 2500 and 2250m, an Alnus-dominantpollen assemblage appears while below 2250m Castanop-

sis-dominant pollen assemblages are common. Cyclobala-

nopsis pollen is expected to prevail in the Quercus Zone ifsampling in different parts of this zone is wide enough tocover more associations of this zone. Nevertheless, theUpper Quercus Zone may sometimes also be representedby a Castanopsis-dominant pollen assemblage associatedwith Cyclobalanopsis and Alnus, even though Cyclobala-

nopsis is common in this zone. This is possibly becausesome of the prevailing genera in the zone belong to theCastanopsis pollen types, such as Castanopsis carlesii.

Castanopsis-type pollen includes Castanopsis, Lithocarpus

and Pasania, totaling 26 species. However, Castanopsis-

dominant pollen assemblages in the Quercus Zone (above1500m) can still be differentiated from those of theCastanopsis–Machilus Zone (below 1500m) if there existsignificant associated elements in the pollen assemblages.The latter are characterized by Castanopsis associated withsubtropical to warm-temperate elements such as Elaeocar-

pus, Diospyros and Euphorbiaceae, and abundant spores,which are different from those of the Castanopsis-dominantassemblages at higher altitudes.

3. Methods

3.1. Chronology

The 39.5-m-long core was taken in the center of thissmall, rectangular basin. The sediment from 39.5 to 32.8mdepth is clay. The upper 32.8m is mainly peaty sedimentsintercalated with thin layers of clay or gyttja except forbackfill in the top 0.3m. Each sample for analysis wasabout 1 cm3, with an average sampling interval of 9 cm.The total number of samples is 395, yielding 114 pollentaxa. Thirty-one radiometric analyses were performed,including three AMS and 28 radiometric 14C dates. Eachsample for conventional 14C dating was 6–10 cm in length.The sedimentation rate is relatively constant, as shown inFig. 3. Ages of sediments beyond the limit of 14Cradiometric dating are extrapolated by tentatively correlat-ing the Alnus-dominant interval with MIS 4 (MIS 3/4,23.3m and MIS 4/5a, 26.5m) (Martinson et al., 1987). Thishigh Alnus-interval, representing cold/dry conditions, ismost likely to correspond to MIS 4. It contrasts with thelayer beneath where less cold and less dry elements, i.e.

Castanopsis or Cyperaceae, are still significant. The bottomof this core at 39.5m is estimated as 95.2 kyr BP by theleast-squares equation shown in the figure, and the ages ofdepths between 39.5 and 26.5m are then extrapolated.

3.2. Vegetation reconstruction

Yu et al. (2002) transferred the surface pollen assem-blages of Salixian (Liew and Chung, 2001) into modernvegetational types by the biomization technique (Prenticeet al., 1996) by which vegetation can be described bybiomes and major vegetation categories defined on thebasis of their dominant plant functional types (PFTs).However, the ecological reference is not as complete at thattime as it is at present and the results show overlapsbetween the upper boundary of subtropical/warm tempe-rate and also between warm-temperate/temperate vegeta-tion types. In this study, we slightly modified (Tables 2 and3) the previous work of Yu et al. (2002) with reference tothe altitudinal vegetational zones of Su (1984) (Fig. 2) andalso to newly available ecological data (Editorial Commit-tee of the Flora of Taiwan, 1993, 1994, 1996, 1998, 2000).For example, PFT sut are those broadleaved evergreenplants that appear in subtropical evergreen forest (Machi-

lus–Castanopsis Zone of Su; 500–1500m in altitude centralTaiwan). We attempted to name biomes by following theaforementioned altitudinal zones proposed by Su (1984).Thus, the tropical evergreen forest corresponds to theFicus–Machilus Zone (o500m; 423 1C) and subtropicalevergreen forest to the Machilus–Castanopsis Zone(500–1500m; 17–23 1C); warm-temperate evergreen forestto the Lower Quercus Zone (1500–2000m; 14–17 1C) andtemperate broadleaved and conifer mixed forests (com-prised of the montane evergreen forest, montane mixedconiferous forest; montane deciduous forest) to the UpperQuercus Zone (2000–2500m; 11–14 1C); cool-temperateconiferous forest to the Tsuga–Picea Zone (2500–3100m;8–11 1C). We also included in the biome list the tropicalrain forest occurring in southern but not in central Taiwan,and for the biomes absent in Taiwan we followed Yu et al.(2002), and Editorial Committee of the Vegetation ofChina (1980) as a reference to forest steppe.A test of modern forest reconstruction is carried out by

using the same set of surface pollen assemblages in Salixianthat was used by Yu et al. (2000). We apply two strategieswhen assigning Castanopsis-type pollen in PFTs: (1)include Castanopsis in PFTs sut and wte2, i.e. insubtropical and warm-temperate forests since Castanopsis

is the main forest element of subtropical and warm-temperate forests; (2) include Castanopsis in PFTs sub,wte2 and wte1, i.e. in subtropical, warm temperate and alsotemperate broadleaved and conifer mixed forests, sincefour of 26 species of Castanopsis-type pollen grow intemperate broadleaved and conifer mixed forests. Amongthe 16 sites between altitudes 700 and 2800m in theSalixian area, the result of strategy (1) shows two sitesincorrectly assigned (altitudes 2000 and 2150m: temperate

ARTICLE IN PRESS

Fig. 3. Ages and information used to establish age–depth relations at Toushe bog. Radiocarbon yr were converted to calendar yr (kyr) by use of refs Bard

et al. (1998) and Stuiver and Reimer (1993).

P.-M. Liew et al. / Quaternary International 147 (2006) 16–3320

broadleaved and conifer mixed forests are incorrectlyassigned to warm temperate evergreen forest). The resultof strategy (2) shows three sites incorrectly assigned(altitudes 1500m: warm-temperate forest incorrectly as-

signed to temperate broadleaved and conifer mixed forest;1780m: warm-temperate forest incorrectly assigned tosubtropical forest; 2150m: temperate broadleaved andconifer mixed forests incorrectly assigned to subtropical


forest). In Japan, Gotanda et al. (2002), followingTakahara et al. (2000), studied the reconstruction of forestsby surface pollen samples. They improved the reconstruc-tion of present forests by assigning Fagus to temperatedeciduous forest instead of several forest types andexcluding Gramineae. For the biomization of the Toushefossil pollen sequence, we use strategy (1) based on thebetter results of the modern forest reconstruction inSalixian, by assigning Castanopsis in subtropical andwarm-temperate forests (Tables 2 and 3).

4. Palynostratigraphy of the Toushe bog

4.1. Palynological zones

The pollen zones are described as follows and also inTable 1. The percentage of each pollen genus is based onthe total pollen sum, whereas that of spores is based on thesum of pollen and spores (Figs. 4.1 and 4.2). In thefollowing discussion, years (e.g. 2.9 kyr BP) representcalibrated years, and 14C years are expressed as 2900 yr BP.

Zone 20 (39.5–39.0 m, tentatively estimated as 95.2–

94.4 kyr BP): arboreal pollen (AP) is about 70% in whichCastanopsis is dominant (460%). Other associated ele-ments are Cyclobalanopsis, Quercus and Symplocos.


91.4 kyr BP): AP still prevails but Cyperaceae and Grami-neae continuously increase. Among the AP, Castanopsis

and Salix are the most important. Associated elementsare Quercus and Cyclobalanopsis. Compared with theprevious zone, Salix increases to more than 20% at theexpense of Castanopsis. Liquidambar and Ilex values alsoincrease.


88.8 kyr BP): is characterized by an abrupt increase ofPteridophytes (460%). AP is dominant, Symplocos

(450%) and Myrica (25%) being the most common ones.Zone 17 (35.6–30.5 m, tentatively estimated as 88.8–

80.5 kyr BP): AP reaches 60%, slightly less than in theprevious zones in which the major element Castanopsis

(20–40%) again reaches its dominant situation. Myrica

reaches 15% in the lower part. Cyperaceae increase upwardto 30%.

Zone 16 (30.5–29 m, tentatively estimated as 80.5–

78.0 kyr BP): is characterized by a sharp decrease ofCastanopsis, from 40% to o15%, and herbs outnumberarboreal pollen for the first time. Cyperaceae increase to40% or more, whereas Salix increases remarkably in theupper part at the expense of Cyperaceae.

Zone 15 (29–28.2 m, tentatively estimated as 78.0–

76.7 kyr BP): exhibits remarkable changes in both APand NAP (non-arboreal pollen). AP dominates in this zone(80%) but instead of Castanopsis, the major tree pollen areIlex (40%) and Alnus (up to 70%). Alnus reaches its climaxfor the first time in this sequence. Castanopsis is at about5%, even less than in Zone 16, and is lower than

Cyclobalanopsis. Cyperaceae decrease sharply, while theArtemisia content rises slightly.


73.9 kyr BP): Cyperaceae dominate in the lower part. Alnus

sharply decreases while Cyclobalanopsis increases. In theupper part Alnus reaches 40%. Cyclobalanopsis (about15%) is higher than Castanopsis and maintains this trendduring the glacial. Artemisia is relatively higher in Zones 14and 15.

Zone 13 (26.5–23.3 m, tentatively assigned as 73.9–

59.0 kyr BP): AP dominates (480%) with Alnus as themajor component (generally 60% or more). Salix increaseswhile Cyclobalanopsis decreases in comparison with theprevious zone. Cyperaceae decrease as well. Pinus decreasesfrom Zone 15 upward.

Zone 12 (23.3–23 m), tentatively estimated as 59.0–

57.6 kyr BP: is characterized by a decrease of Alnus

(20%) and Salix and the increase of Ilex (from o5% to425%).


54.0 kyr BP): Alnus predominates again (60%). Comparedwith Zone 13, Castanopsis and Symplocos increase at theexpense of Salix. Symplocos occasionally increases inZones 11 and 12.

Zone 10 (22.4–21.0 m, tentatively estimated as

54.0–48.5 kyr BP): Alnus decreases remarkably to about40% or even less, although it is still the main component ofAP. Cyclobalanopsis and Castanopsis are relatively sig-nificant, similar to the last two zones 12 and 11. Ilex andSymplocos decrease. Cyperaceae dramatically increaseagain. Castanopsis is relatively higher from Zones 12 to10, after its decrease to a very low value in Zone 13.


36.9 kyr BP): Alnus has the same amount as in Zone 10but peaks at the middle. Cyperaceae frequently fluctuate atthe expense of Alnus. The most notable feature is theincrease of Pteridophytes, especially monolete spores. Salix

increases episodically in this zone. Castanopsis decreasesslightly and maintains the trend from this zone upwarduntil the beginning of the Holocene. Ilex is common fromZone 12 upward.

Zone 8 (18.4–16 m, cal. 36.9–31.2 kyr BP; 14C years,

41,100–31,600 yr BP): Pteridophytes and Cyperaceae de-crease sharply. Compared with the previous zone Alnus

and Ilex increase while Cyclobalanopsis decreases. Grami-neae increase slightly.

Zone 7 (16–14.6 m, 31.2–27.9 kyr BP; 31,600–23,900 yr

BP): Cyclobalanopsis slightly increases. Alnus is stilldominant with a level similar to the previous zone. Ilex

and Symplocos decrease. Castanopsis increases slightly.Alnus is relatively low but with remarkable fluctuationsfrom Zones 10 to 7.

Zone 6 (14.6–13.8 m, 27.9–27.4 kyr BP; 23,900–23,400 yr

BP): compared with Zone 7, Alnus increases clearly.Cyclobalanopsis, Castanopsis, Quercus, Ligustrum andSalix decrease. Artemisia decreases slightly. Zones 6–12are assumed to belong to MIS 3.

ARTICLE IN PRESSTable

1

Toushebogpollen

zones

withinferred

paleovegetationandpaleoclim

ate

Zonedepth

andage

OIS

andage

Characteristics

Paleovegetation

Paleoenvironment

1b(1.4–0.3m)3.8–1.8kyrBP

1Herbaceouspollen

rise

(70–80%

).Increase

inL

iqu

ida

mb

ar;decrease

in

Cy

clo

ba

lan

op

sis,

Ilex.CyperaceaeandGramineaefrequent.Increase

in

pteridophytes

Grassland

Subtropicalto

warm

temperate,wet

1a(2.5–1.4m)5.7–3.8kyrBP

0–12.1kyr

Herbaceouspollen

increase.Increase

inS

ali

x,

Sy

mp

loco

s,Il

ex;decrease

inM

all

otu

s.Increase

inCyperaceae

Subtropicalforest

but

fluctuated

Fluctuatedsubtropicalto

temperate

2c(3.1–2.5m)6.3–5.7kyrBP

Increase

inIl

ex,

Lig

ust

rum;decrease

inP

inu

s.Decrease

inCyperaceae

andpteridophytes

Subtropicalto

tropical

forest

Subtropical,less

wet

2b(3.9–3.1m)7.0–6.3kyrBP

Increase

inGramineaeandCyperaceae,

Sa

lixpeaksatfirstandthen

decrease.Increase

inP

inu

s.Increase

inpteridophytes(to50%)

Subtropicalforest

mainly

Subtropical,wet

2a(4.7–3.9m)8.0–7.0kyrBP

Woodytaxasum

increase

slightly.Increase

inIl

exand

Mall

otu

s,S

ali

x

peakatearlypart.Sharp

decrease

inpteridophytesandCyperaceae

Subtropicalforest

but

fluctuated

Fluctuatedsubtropicalto

temperate

less

wet

3(7.10–4.7m)11.0–8.0kyrBP

Woodytaxasum

decreases(to40%

).Increase

inC

ast

an

op

sis,

Tre

ma,

Pin

us;decrease

inC

ycl

ob

ala

no

psi

sand

Sy

mp

loco

s.S

ali

xvaries;peakof

Ilex

atmiddle.Increase

inCyperaceaeandGramineae,sharp

increase

in

pteridophytes

Subtropicalto

warm

-

temperate

forest

Subtropicalto

warm

temperate,wet

4d(7.6–7.10m)11.9–11.0kyrBP

Increase

inC

ycl

ob

ala

no

psi

s,S

ym

plo

cosand

Sa

lix;increase

in

Gramineae(to40%)

Tem

perate

tosubtropical

forest

Tem

perate,less

dry

4c(9.2–7.6m)14.5–11.9kyrBP

WoodytaxaA85%

.Increase

inS

ali

x,

Sy

mp

loco

s.Decrease

in

Cyperaceaeand

Art

emis

ia.Gramineaeislow

butpeakatend.Decrease

inpteridophytes

Tem

perate

forest

Tem

perate,less

dry

4b(9.8–9.2m)15.7–14.5kyrBP

2Woodytaxasum

varies,increase

inA

lnu

s.Increase

inCyperaceae.

Sharp

increase

inpteridophytes

Warm

-tem

perate

forest

Warm

temperate,moistto

wet

4a(10.3–9.8m)16.7–15.7kyrBP

12.1–24.1kyr

Woodytaxarise

(to70%),decrease

inA

lnu

s;increase

inIl

ex,

Sym

plo

cos,

Cy

clob

ala

no

psi

s.Decrease

inCyperaceaeandGramineae

Tem

perate

forest

Tem

perate

less

dry

5(13.8–10.3m)27.4–16.7kyrBP

Decrease

ofwoodytaxapercentages,herbsrise

(to75%)ofpollen

sum,

Gramineaerise

(to50%

).Decrease

inA

lnu

s(to20%

);increase

in

Cy

clo

ba

lan

op

sis,

Ilex

,S

ym

plo

cos.Increase

inA

rtem

isia

(to10%),

Cyperaceae

Tem

perate

forest

toforest

steppe

Tem

perate,dry

6(14.6–13.8m)27.9–27.4kyrBP

WoodytaxaA80%

;increase

inA

lnu

s;decrease

inC

ycl

ob

ala

no

psi

s,

Ca

sta

nop

sis,

Qu

ercu

s,L

igu

stru

mand

Sali

x.Decrease

inCyperaceaeand

Art

emis

ia

Tem

perate

deciduousforest

Tem

perate

7(16–14.6m)31.2–27.9kyrBP

Woodytaxasum

varies

60–90%,

Aln

usfluctuatedatthecompense

of

Cyperaceae.

Increase

inC

ycl

ob

ala

no

psi

sand

Ca

sta

nop

sis.Increase

in

Sali

xattheearlypart;decrease

inIl

exand

Sy

mp

loco

s,peakin

Gramineaeatend

Tem

perate

deciduousforest

Tem

perate

8(18.1–16m)36.9–31.2kyrBP

3Woodytaxasum

increase

A80%

,A

lnu

svaries

andpeakatmiddle;

increase

inIlex;

Cy

clo

ba

lan

op

sisslightlydecrease;decrease

in

Cyperaceaeandincrease

inGramineae.

pteridophytesdecrease

sharply

Tem

perate

deciduousforest

Tem

perate,gettingdrier

9(21.0–18.4m)48.5–36.9kyrBP

27.6–58.9kyr

Woodytaxasum

fluctuates40–85%

,decrease

inC

ast

an

op

sis.

Fluctuationof

Aln

usatthecompense

ofCyperaceae.

Increase

in

Sym

plo

cos;tw

opeaksof

Sali

xatmiddle

andso

does

Ilex;increase

in

pteridophytes(to60%

)

Tem

perate

deciduousforest

Tem

perate,moistto

wet

10(22.4–21.0m)54.0–48.5kyrBP

Woodytaxasum

decreasesandthen

increases.Increase

in

Cy

clo

ba

lan

op

sisand

Ca

sta

no

psi

s.Decrease

inA

lnu

s(to40%),

Ilex,

Sym

plo

cos;Increase

inCyperaceae

Tem

perate

deciduousforest

Tem

perate,less

dry

11(23.0–22.4m)57.6–54.0kyrBP

WoodytaxaA80%,increase

inA

lnu

s(to60%);

Ca

sta

nop

sisthesameas

thepreviouszone.

Decrease

inIl

exand

Sa

lix.Increase

inGramineae

Tem

perate

deciduousforest

Tem

perate,dry


ARTICLE IN PRESS12(23.4–23.0m)59.0–57.6kyrBP

4Increase

inIl

ex(to25%),

Ca

sta

nop

sis,

Sy

mp

loco

s.Decrease

inA

lnu

s(to

20%)and

Sa

lix

Tem

perate

deciduousforest

Tem

perate

13(26.6–23.4m)assigned

as

73.9–59.0kyrBP

58.9–73.9kyr

WoodytaxaA80%,mainly

Aln

us(to60%

),increase

inS

ali

x;1peakin

Sym

plo

cos;decrease

inC

ycl

ob

ala

no

psi

s.Decrease

inCyperaceae

Tem

perate

deciduousforest

Tem

perate,dry

14(28.2–26.6m)76.7–73.9kyrBP

Woodytaxasum

varies

30–70%,

Aln

usdeclinebutrisesatin

thelater

part(to40%

),C

ycl

ob

ala

no

psi

s(15%)higher

than

Ca

sta

nop

sis;decrease

inS

ali

x,increase

inCyperaceae(to50%),

Art

emis

iasimilarto

the

previouszone

Tem

perate

deciduousforest

Tem

perate,less

dry

15(29–28.2m)78.0–76.7kyrBP

5a?

WoodytaxaA80%;declinein

Ca

sta

nop

sis(to5%

)and

Sa

lix.Increase

inIl

ex(40%)andthen

Aln

us(70%),decrease

inP

inu

s,increase

in

Art

emis

ia,decrease

inCyperaceae

Tem

perate

deciduousforest

Tem

perate,gettingdry

16(30.5–29m)80.5–78.0kyrBP

73.9–85.1kyr

Woodytaxasum

varies

A40%,declinein

Ca

sta

nop

sis(15%).Increase

inS

ali

x(to40%

).Increase

inCyperaceae(to40%

)andGramineae

Tem

perate

deciduousforest

Tem

perate,moist

17(35.6–30.5m)88.8–80.5kyrBP

WoodytaxaA60%

butupto

80%

atlower,

Ca

sta

no

psi

svaries

(20–40%

).M

yri

cadecreasesupward.Increase

inCyperaceae(to30%

),

decrease

inpteridophytes(10%

)

Subtropicalto

warm

-

temperate

forest,less

closed

Subtropicalto

warm

temperate,less

wet

18(37.2–35.6m)91.4–88.8kyrBP

5b?

Woodytaxasum

varies

50–90%,declinein

Ca

sta

nop

sis(o

15%

),

increase

inS

ym

plo

cos(to50%)and

My

rica

(25%).Increase

in

Poly

go

nu

mandpteridophytes(to80%)

Tropicalto

subtropical

forest

Subtropical,wet

19(39.0–37.2m)94.4–91.4kyrBP

85.1–93.6kyr

Woodytaxasum

60–85%

,decrease

inC

ast

an

op

sis,increase

inS

ali

x(to

20%)andalso

Ilex,

Liq

uid

am

ba

rand

Lig

ust

rum.Increase

inGramineae

andCyperaceae

Tem

perate

forest

Tem

perate,moist

20(39.0–39.5m)95.2–94.4kyrBP

5c?

493.8kyr

WoodytaxaA70%

;dominanttaxais

Ca

sta

no

psi

s(to60%

).

Cy

clo

ba

lan

op

sis,

Qu

ercu

s,S

ym

plo

cosand

Pin

usalsosignificant;

Cyperaceaeabout20%,pteridophytesare

low

Warm

-tem

perate

forest

Warm

-tem

perate,moist


ARTICLE IN PRESS

Fig. 4.1. Pollen diagram for the Toushe Basin. Percentage of each pollen genus is based on total pollen sum.


ARTICLE IN PRESS

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

2600

2700

2800

2900

3000

3100

3200

3300

3400

3500

3600

3700

3800

3900

4000

Dep

th (

cm)

1840 ± 502230 ± 50

4230 ± 504410 ± 404800 ± 50

5640 ± 60

6480 ± 607370 ± 60

8780 ± 60

9600 ± 13010059 ± 8710309 ± 89

12100 ± 90

12350 ± 90

13700 ± 10013900 ± 10015200 ± 110

18150 ± 120

20500 ± 100

23400 ± 190

23900 ± 150

28000 ± 250

29300 ± 300

31100 ± 400

31600 ± 350

32800 ± 500

37200 ± 60039200 ± 600

8270 ± 70

>43000

>41000

>43000

>40000

>45000>41000

Age

(C

-14

yr B

P)

20

Artemisi

a

20

Polygo

num

Umbelli

ferae

20 40 60 80

Cypera

ceae

20 40 60 80

Gramine

ae

20 40 20 40 60 80 20 40 60 80 100

Zone

1b

1a

2c

2b

2a

3

4d

4c

4b4a

5

6

7

8

9

10

1112

13

14

15

16

17

18

19

20

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

Subtropical evergreen forestWarm-temperate forest

Tropical evergreen forestTemperature deciduous and conifer mixed forest

Mon

olete

spor

eother

Trilete

spor

e

Potamog

etonac

eae

DCAaxis-1

BiomesLyg

odium

(%)

Fig. 4.2. Percentage of each spore genus is based on sum of pollen and spore. Reconstructed biomes plotted stratigraphically in relation to sample scores

on the 1st axis of a detrended correspondence analysis of the pollen data.



Zone 5 (13.8–10.3 m, 27.4–16.7 kyr BP; 23,400–13,800

yr BP): NAP prevails in the middle and upper parts of thiszone in which Gramineae (up to 40% once in the upperpart) as well as Artemisia (at about 10%) reach theirhighest values. Alnus decreases remarkably to less than20% and Cyclobalanopsis increases slightly. Symplocos ishigher than in the previous zone but decreases graduallyupward in the upper part of this zone. This zone belongs toMIS 2.

Zone 4 (10.3–7.10 m, 16.7–11.0 kyr BP; 13,800–9700 yr

BP): differs from the previous zone remarkably. The forestelements rise again and NAP falls. AP increases to 80% inthe upper part. Cyclobalanopsis together with Ilex,Symplocos and Salix are the main woody elements.Gramineae decrease. Due to the abrupt change ofassemblages, the zone is divided into three subzones. Insubzone 4a (10.3–9.8m) Cyperaceae sharply decrease. Ilex,

Cyclobalanopsis and Symplocos increase. NAP is clearlylower. In subzone 4b (9.8–9.2m) spores increase abruptlyand Cyperaceae also increase. Alnus is higher and Ilex islower than in the previous subzone. Cyclobalanopsis

maintains the same level as previously. In subzone 4c(9.2–7.6m) spores decrease remarkably. Symplocos drama-tically increases in the lower part and Salix in the upperpart. Ilex is common. Herbs are relatively low. In subzone4d (7.6–7.1m) Gramineae rise to 40%. Salix reaches itshighest value in the upper part.

Zone 3 (7.10–4.70 m, 11.0–8.0 kyr BP; 9700–7200 yr BP):Pteridophytes are high. Castanopsis is dominant amongAP. Trema increases. Salix, Symplocos and Ilex arereduced. NAP increases again. It is probably hydrophyllusbecause of the accompanying large amount of fern-spores.AP is higher than NAP.

Zone 2 (4.70–2.50 m, 8.0–5.7 kyr BP; 7200–4900 yr BP):is characterized by the increase of Ilex and Mallotus.Pteridophytes reach their maximum value in the middlepart. Three subzones are distinguished here: In sub-zone 2a, Salix, Ligustrum (12–15%) and Ilex (25%)increase again. Cyclobalanopsis decreases. Cyperaceae arereduced. Pteridophytes decrease remarkably. Mallotus

appears from the middle part of this zone upward. Insubzone 2b Pteridophytes increase to maximum (ave-rage in 50%). Ilex decreases while Pinus increases. Insubzone 2c, Pinus is lower while Symplocos and Ilex riseagain. Herbs increase again. Ligustrum and Symplocos alsoincrease.

Zone 1 (2.50–0.30 m, 5.7–1.8 kyr BP; 4900–1800 yr BP):is characterized by the increase of Cyperaceae. Salix

increases but Ilex decreases. Herbs reach their maxi-mum values. Cyperaceae and monolete spores becomeimportant. This zone is further divided into two subzonesdue to the changing amounts of NAP. In subzone 1a(2.5–1.4m) Pinus is lower while Symplocos and Ilex riseagain. Salix increases but monolete spores decrease.Cyperaceae also increase upward. In subzone 1b (1.4mupward) Cyperaceae reach their maximum. Monoletespores increase as well.

4.2. Paleovegetation: a quantitative reconstruction

The characteristics of vegetation of pollen spectra fromToushe Basin appear in Fig. 4.2 according to PFTs andbiomes shown in Tables 2 and 3 with the biomes plotted onthe 1st axis of detrended correspondence analysis (DCA byTilia; Grimm, 1997). The results show that subtropicalevergreen forest dominated during the Holocene, incontrast to temperate broadleaved and coniferous mixedforests, specifically the temperate deciduous forest withinthem, during the last glacial.Vegetation reconstruction shows that the Castanopsis-

dominant pollen assemblages of the early glacial are mainlysubtropical to warm-temperate evergreen forests exceptZone 19. The warmest conditions are in Zone 18 (tropicaland subtropical forests) and the lower part of Zone 17(subtropical to warm-temperate forests). Thus, Zone 19,where temperate broadleaved and conifer mixed forestsprevailed, might correspond to MIS 5b. From Zones 16 to4, the temperate broadleaved and conifer mixed forests,especially the deciduous forest, dominated except for someintervals of the last glacial at cal. 41.6, 38.0 and 37.3 kyr BPand at 22.3 and 18.9 kyr BP as well as 15.1 kyr BP wherewarm-temperate evergreen forest or subtropical forestappeared. It shows a distinct interstadial at about42–37 kyr BP. The warm conditions occurred at 22.3 and18.9 kyr BP just before and within the dry phase (Grami-neae prevail) of the late stadial. However, due to highamounts of Gramineae in these samples, this result needsto be further discussed. Nevertheless, an abrupt warmphase around 22 ka is reported in the Siple Coast ofAntarctica (Taylor et al., 2004) and a warm phase very nearLast Glacial Maximum (LGM) is also reported in NewZealand (Hormes et al., 1999). Post-Bølling subtropicalconditions are found at 11.5 kyr BP. Thus, the subtropicalconditions of 15.1 kyr BP (depth 9.59m) and 11.5 kyr BP(depth 7.28m) of this study correspond to the spikes ofAtlantic melting events (Bond et al., 1992). After10.7 kyr BP, subtropical conditions continue. Tropicalforest appeared at 6.9 and 6.1–5.9 kyr BP. Temperatebroadleaved and conifer mixed forest appeared at about11.2–11.0, 7.5, 7.2 and 7.1, 5.2, 5.0 and 4.9 kyr BP. The coolinterval at 3.7–2.0 kyr BP which was found in alpine lakesof Taiwan (Liew and Huang, 1994) appeared here only as achange from subtropical to warm-temperate forests. Itindicates that it is a less prominent cooling than those inthe first half of the Holocene. Subtropical and tropicalforests are frequent from 8 to 5 kyr BP. Warm-temperateevergreen forest is common in early Holocene before8 kyr BP.However, the result of biomization shows that samples

with equal score of warm-temperate evergreen forest andsubtropical evergreen forest are common although theyshould be assigned as warm-temperate forest according tothe rule of less number of PFTs in biomization (among thesamples assigned as warm-temperate forest are almost withthe same score as subtropical forest except at depths 31.1,

ARTICLE IN PRESSTable

2

Assignmentofpollen

taxato

plantfunctionaltypes

(PFT)

PFTcode

Pollen

taxa

teF

icu

s,L

ith

oca

rpu

s,B

isch

offi

a,

Ho

ma

lan

thu

s,P

alm

ae,

Pip

erace

ae,

Tre

ma,

Alb

izzi

a,

Aca

cia,

Cel

tis,

Sch

effl

era,

Ard

isia,

My

rica,

Ela

eoca

rpu

s,S

loa

nea,

Ma

llo

tus,

Om

ala

nth

us,

Ma

cara

nga,

Mel

ano

lep

is,

Glo

chid

ian,

Da

phn

iph

yll

um,

Cit

rus,

Za

nth

ox

ylu

m,

Ch

lora

nth

us,

Sa

piu

m,

Mic

hel

ia,

Mel

ia,

Alg

aia,

Sy

zyg

ium,

Hel

icia,

Mel

iosm

a,

Sty

rax,

Wen

dla

ndia,

My

rsin

e,V

ibu

rnu

m,

Sy

mp

loco

s,L

igu

stru

m,

Sa

ura

uia,

Ilex,

Ka

nd

elia,

Rh

izo

ph

ora,

Lu

mn

itze

ra,

Dy

sox

yll

um,

Ara

lia,

Fra

xin

us,

Osm

an

thu

s,C

all

ica

rpa,

Cy

cas,

Lager

stro

emia,

Ma

esa,

Dio

spy

ros,Rutaceae,

Combretaceae,

Moraceae,

Leguminosae,

Proteaceae,

Melastomaceae,

Ulm

aceae

trD

iosp

yro

s,D

yso

xy

lum,

Ag

laia,

Alb

izzi

a,

Ter

min

ali

a,

Fic

us,

Sy

zyg

ium,

Bo

mb

aca

cea

e,B

om

ba

x,

Co

mb

reta

cea

e,E

up

ho

rbia

cea

e,L

egu

min

osa

e,M

ela

no

lepis,

Mic

rotr

op

is,Myrsinaceae,

Proteaceae,

Sapotaceae,

Ulm

aceae,

Ulm

us,

Wen

dla

nd

ia

sut

Cy

clo

ba

lan

op

sis,

Ca

sta

no

psi

s,L

ith

oca

rpu

s,P

asa

nia,

Cry

pto

cary

a,

Sch

effl

era,

Ard

isia,

My

rica,

Ela

eoca

rpu

s,S

loa

nea,

Pla

tyca

rya,

Mall

otu

s,D

ap

hn

iph

yll

um,

Mic

hel

ia,

Mel

iosm

a,

Ilex,

Dio

spy

ros,

Eng

elh

ard

tia,

My

rsin

e,S

chim

a,

Ma

esa,

Fra

xin

us,

Lig

ust

rum,

Osm

an

thu

s,P

run

us,

Call

icarp

a,

Act

inid

ia,

Sa

ura

uia,

Ca

pa

pa

ris,

An

aca

rdia

cea

e,A

rali

ace

ae,

Cit

rus,

Zel

ko

va,

Ch

lora

nth

us,

Ca

mel

lia,

Hel

icia,

Sy

mp

loco

s,S

yzy

giu

m,

Cel

tis,

Za

nth

ox

ylu

m,

Sa

piu

m,

Vib

urn

um,

Cy

cas,Moraceae,

Rhamnaceae,

Rubiaceae,

Rutaceae,

Ebenaceae,

Meliaceae,

Apocynaceae,

Euphorbiaceae,

La

ger

stro

emia

wte2

Cy

clo

ba

lan

op

sis,

Ca

sta

nop

sis,

Lit

hoca

rpu

s,Q

uer

cus,

Vib

urn

um,

Da

phn

iph

yll

um,

Sch

ima,

Ara

lia,

My

rsin

e,L

igu

stru

m,

Osm

an

thu

s,E

laeo

carp

us,

Tro

cho

den

dro

n,

Act

inid

ia,

Cle

yer

a,

Eu

rya,

Go

rdon

ia,

Pla

tyca

rya,

Den

dro

pa

na

x,

Illi

ciu

m,

Ilex,

Mel

iosm

a,schffleraMagnoliaceae,

Aaliaceae,

Hydrangeaceae,

Sym

plo

cos

wte1

Ilex,

Lig

ust

rum,

Cy

clob

ala

no

psi

s,Q

uer

cus,

Sho

rtia,

Vib

urn

um,

Tro

chod

end

ron,

Sy

mp

loco

s,P

run

us,

Act

inid

ia

ts1

Aln

us,

Rib

es,Ulm

aceae,

Sali

x

ts2

Ca

rya,

Aln

us,

Ela

eog

nu

s,F

ag

us,

Ju

gla

ns,

Liq

uid

am

ba

r,P

tero

cary

a,

Qu

ercu

s,S

ali

x,

Ca

sta

nea,

Ca

rpin

us,

Zel

ko

va,

Ulm

us,

Hel

win

gia,Ulm

aceae

ts3

Rh

us,

Zel

ko

va,

Lag

erst

roem

ia,

Sa

pin

du

s,P

laty

cary

a,

Sa

piu

m,

Tax

illu

s,C

elti

s,U

lmus,

Liq

uid

am

ba

r,T

rem

a,

Ko

elre

ute

ria,

Ter

min

ali

a,

Alb

izia,

Hel

win

gia,Ebenaceae.

Dio

spy

ros,

Fra

xin

us

tsA

can

tho

pa

na

x,

Ace

r,V

ibu

rnu

m,

Aln

us,Ulm

usRutaceae,

Rosaceae,

Rhamnaceae

ecP

inu

s,J

un

iper

us

wtc

Ket

elee

ria,

Pod

oca

rpus,

Ca

loce

dru

s,C

epha

lota

xis

tcC

ha

macy

pa

ris,

Cry

pto

mer

ia,

Cu

nn

ing

ha

mia,

Ta

iwan

ia,

Pin

us,Taxodiaceae

ctc

Pic

ea,

Tsu

ga

bec

Ab

ies

tef

Imp

ati

ens,

Mic

role

pia,

Cu

scu

ta,

Za

nth

ox

ylu

m,

Ru

ma

x,

Ch

eno

pod

ium,

Am

ara

nth

us,

Cle

ma

tis,

Ra

nu

ncu

lus,

Co

ccu

lus,

Ny

mp

ha

ea,

Hy

dra

ng

ia,

Ch

lora

nth

us,

Hy

per

icu

m,

Dro

sera,

Ara

bis,

Ka

lan

choe,

Sed

um,

Deu

tzia,

Pit

tosp

oru

m,

Ro

sa,

Ru

bu

s,S

an

guis

orb

a,

Rh

am

nu

s,C

issu

s,E

laeo

gn

us,

Beg

onia,

Act

inost

emm

a,

Mel

ast

om

a,

Bre

dia,

Epil

obiu

m,

Lud

wig

ia,

Tra

pa,

My

rio

ph

yll

um,

Hel

win

gia,

Sch

effl

era,

Tet

rap

an

ax,

Sho

rtia,

Ma

esa,

Ard

isia,

My

rsin

e,L

ysi

ma

chia,

Sty

rax,

Sy

mp

loco

s,G

enti

an

a,

Ga

liu

m,

Ca

llic

arp

a,

Call

itri

che,

Sola

nu

m,

Ju

stic

ia,

Str

ob

ila

nth

us,

Pla

nta

go,

Vib

urn

um,

Sa

git

tari

a,

Pota

mo

get

on,

Mu

sa,

Bry

op

hy

llu

m,

Typ

ha,

Sta

uto

nia,

Pip

er,

Act

inid

ia,

Lo

ran

thus,

Mic

rotr

op

is,

Wir

kst

roem

ia,Acanthaceae,

Gesneriaceae.

Gramineae

tfA

ctin

ost

ema,

Gen

tian

a,

Cu

scu

ta,

Ga

liu

m,

Po

lyg

onu

m,

Sta

uto

nia,

Hyper

icum,

Ara

bis,

Sed

um,

Deu

tzia,

Hy

dra

ng

ia,

Pit

tosp

oru

m,

Ro

sa,

Ru

bu

s,Im

pati

ens,

Euo

ny

mu

s,R

ha

mnu

s,E

laeo

gn

us,

Epil

obiu

m,

Sh

ort

ia,

Ly

sim

ach

ia,

Pri

mu

la,

Sy

mp

loco

s,S

wer

tia,

Pla

nta

go,

Lon

icer

a,

Cle

mati

s,L

ora

nth

us,

Mic

rotr

op

is,Cucubitaceae,

Gramineae,

Labiatae,

Ranunculaceae,

Rutaceae

Scrophulariaceae,

Solanaceae,

Umbeliferae

af

Po

lyg

onu

m,

Rh

od

od

end

ron,

Tha

lict

rum,

Sa

lix,

Act

inid

ia,

Ju

nip

erus,

Ch

eno

po

diu

m,

Cle

ma

tis ,

Ra

nu

ncu

lus,

Da

mn

aca

nth

us,

Eu

rya,

Ga

liu

m,

Ro

sa,

Lo

nic

era,

Sed

um,Cruciferae,

Ericaceae,

Compositae.

Ber

ber

is,

Rib

es

sfA

rtem

isia,

Ju

stic

ia,

Ru

bu

s

gGramineae,

Compositae

hEricaceae

sCyperaceae

wod

Sy

mp

loco

s,Q

uer

cus,

Ilex,

Cy

clob

ala

no

psi

s

Ferns(x)

Psi

lotu

m,

Lyco

po

diu

m,

Sel

agin

ella,

Eq

uis

etu

m,

Op

hio

glo

ssu

m,

An

gio

pte

ris,

Arc

ha

ng

iop

teri

s,M

ara

ttia,

Osm

un

da,

Lyg

od

ium,

Sch

iza

ea,

Dic

ranopte

ris,

Hem

enophyll

um,

Cib

oti

um,

Cy

ath

ea,

Den

nst

aed

tia,

Mic

role

pia,

Pte

ridiu

m,

Da

vall

ia,

Vit

tari

a,

Wo

od

ward

ia,

Dry

op

teri

s,D

ipte

ris,

Po

lyp

od

ium,

Azo

lla,

Cte

nit

is,

Dip

lazi

un,

Pla

gio

gyri

a,

Mic

roso

rium,

Sel

agin

ella

trx

Cyatheaceae

Key

toPFTcode:te,tropicalevergreen;tr,tropicalraingreen;sut,subtropicalevergreen;wte2,warm

-tem

perateevergreen;wte1,temperate

evergreen;ts1,cool-temperate

summergreen;ts2,interm

ediate-

temperate

summergreen;ts3,southernwarm

-tem

perate

summergreen;ts,temperate

summergreen;ec,eurythermicconifer;wtc,south

warm

-tem

perate

conifer;tc,temperate

conifer;ctc,cool-temperate

evergreen

conifer;bec,borealevergreen

conifer;tef,tropicalandsubtropicalevergreen

forbs/shrubs;tf,temperate

forbs/shrubs;af,arctic-alpineforbs/shrubs;sf,steppeforb/shrub;g,grass;h,Ericaceae;

s,sedge;

wod,woodland;x,ferns;trx,Cyatheaceae.


ARTICLE IN PRESS

Table 3

Assignments of plant functional types to biomes

Biome PFTs

Tropical evergreen forest te, tef, trx, x

Tropical rainforest tr, tef, trx, x, ts3

Subtropical evergreen forest sut, tef, ts3, wtc, trx, x

Warm-temperate evergreen forest wte2, tf, ts3, x

Temperate broadleaved and

conifer mixed forest

wte1, ec, tc, ts1, ts2, ts, tf

Cool-temperate conifer forest ctc, ec, g, h

Cold-temperate conifer forest bec, ec, g, h

Alpine conifer forest ec, af, g

Forest steppe wod, g, sf

Alpine shrub land af, sf, g


35.4, 39.1 and 39.2m where warm-temperate forest has thehigher score). It possibly indicates that further discrimina-tion of the altitudinal zones within the Lauro-Fagaceaeforest using genus level data is not very easy. This is partlydue to the fact that the main pollen types of forests lowerthan the Tsuga–Picea Zone are the Fagaceae—Castanopsis

and Cyclobalanopsis—whose altitudinal spread of species iswide.

The other problem in biomization here is the difficultywhen Gramineae-dominant assemblages are encountered,such as during LGM, due to the wide occurrence ofGramineae in these tropical–subtropical areas. Conse-quently, even though the Gramineae-dominated assem-blages of LGM possibly represent forest steppe or steppeconditions, the biome of temperate broadleaved andconifer mixed forests occurred. We hope more work inthe future will further refine the rule set of the biomes.

5. Interpretation of vegetational history and climatic

conditions

In the pollen diagram, warm elements, such as Castanopsis

and Mallotus, alternated with cold elements, such as Alnus

and Salix. Higher spore values in the diagram are regardedas a proxy of higher precipitation conditions or water-transport processes. Precipitation is usually an index of anintensifying summer monsoon, which in turn representsmore frequent tropical cyclones. Relatively dry conditionsare represented by high values of Gramineae (i.e. Gramineaewithout accompanying large amounts of monolete spores),Alnus and Salix. According to modern vegetation assem-blages (Fig. 2) Alnus and Salix grow in less humid parts ofthe Quercus Zone even though they are well known astemperate, boreal or arctic-alpine trees and shrubs indicatingwet conditions in other places (Tarasov et al., 1998).

5.1. Zones 20–17, tentatively estimated as 95.2–80.5 kyr BP,

probably MIS 5c–a

The early glacial (Zones 20–17) is characterized byassemblages with a high value of Castanopsis-type pollen(20–40%) except Zone 18. Castanopsis-dominant pollen

assemblages usually represent assemblages of subtropicalto warm-temperate forest—Machilus–Castanopsis Zone(500–1500m) in present Taiwan, as shown in pollen recordsstudied earlier (Liew, 1977). However, Castanopsis-domi-nant assemblages of the early glacial have much lowerspore and much higher Cyperaceae content if comparedwith the present Machilus–Castanopsis Zone. They mayindicate a climatic condition less humid than that oftoday’s Machilus–Castanopsis forest. Alternatively, if thoseCastanopsis-type pollen during early glacial are the fewspecies growing higher than 2000m, they may represent aforest within today’s Upper Quercus Zone. The increase ofSalix in Zone 19 indicates a relatively cold trend althoughstill within the temperate broadleaved and conifer mixedforests (the Upper Quercus Zone), which is tentativelyassigned to MIS 5b. After this, a remarkable fluctuationfrom dry to wet is shown in Zone 18 in which Symplocos

and Myrica replace the important role of Castanopsis thenfollowed by high peaks of monolete spores and Polygonum

(91.4–88.8 kyr BP estimated by the age model here). Myrica

presently grows in the low altitude (below 1500m) area ofTaiwan. Whether this wet/warm phase corresponds to thewet event at 88 ka in the loess record of China (Rousseauet al., 2000) needs further study. Castanopsis returns to itsdominant role after this warm–wet phase. Another smallwet/dry fluctuation in the lower part of Zone 17 isindicated by various amounts of Cyperaceae. HigherCyperaceae contents might indicate lower lake levels(Maley and Brenac, 1998). The drought trend in the upperpart of Zone 17 is also witnessed by changes of lithologicalfacies from lake clay to peat. Zones 18 and 17 are assumedto be within MIS 5a. The following zones 16–14 representthe transition from warm to cold conditions.

5.2. Zones 16–14, tentatively estimated as 80.5–73.9 kyr BP

The interval begins with the remarkable decrease ofCastanopsis and increase of Salix, indicating less humidand less warm conditions than before. Fluctuations ofcold/dry to warm/wet conditions from Zones 15 to 14 areshown by the successive dominance of Ilex, Alnus, the lowvalue of Cyperaceae in Zone 15 and the increase ofCyclobalanopsis and Cyperaceae in Zone 14, although stillwithin the temperate broadleaved and conifer mixed forest.

5.3. Zone 13, tentatively assigned as 73.9–59.0 kyr BP,

possibly corresponds to or within MIS 4

Alnus rises to more than 60% and Cyperaceae decreasesharply suggesting spread of Alnus in the area. A pollenassemblage with such high value of Alnus is similar tosurface pollen assemblages between altitudes 2250 and2500m of the present natural forest, central Taiwan. Sharpdecrease of Cyperaceae indicates still drier conditions thanthose of the previous zone. This assemblage represents thetemperate deciduous forest within the present UpperQuercus Zone (or temperate broadleaved and conifer


mixed forests). Most of this zone is probably colder thanthe late stadial (Zone 5), considering the associated woodytaxa of Zone 5.

5.4. Zones 12–6 (59.0–27.9 kyr BP): represent interstadial

conditions of MIS 3

Alnus and Cyperaceae alternately dominated, within thetemperate deciduous forest; Cyperaceae indicate increasinghumidity. Ilex and Cyclobalanopsis increase. Castanopsis

increases from Zones 12 to 10, indicating a warmer trendbetween the early and late stadials. There is a remarkable wetepisode from cal. 42.2 to 37.0 kyrBP (estimated36,100–32,500 yrBP) represented by spore-dominant assem-blages (Zone 9). Warm-temperate forest conditions at 41.6,38.0 and 37.3kyrBP appeared based on forest reconstructionalso. A prominent wet episode (35–25kyrBP) during MIS 3has been documented by An (2000). Compared with thisstudy, its age appeared to be younger.

The upper part of this interstadial (from Zone 9 upward)appeared relatively drier than the lower part as revealed bythe amounts of Gramineae. Castanopsis has its lowest valuebetween Zones 9 and 6 although showing a slight increasein Zone 7.

5.5. Zone 5, 27.4–16.7 kyr BP, late stadial, belongs to MIS 2

Vegetation in Zone 5, especially the upper part, ischaracterized by dominance in NAP, representing atemperate forest or possibly forest steppe. Between 23.2and 18.7 kyr BP Gramineae and Artemisia reach theirhighest values, indicating relatively dry and sometimescold conditions. Cyperaceae replace Gramineae at about18.6 kyr BP and warm elements including Symplocos, Ilex

and Cyclobalanopsis increase at about 16.7 kyr BP. How-ever, among the woody elements, Cyclobalanopsis ratherthan Alnus or Pinaceae appear. This is the intervalcorresponding to the LGM. According to the surfacepollen study of lowland northeast China, 40% NAP marksthe existence of forest-steppe zone, and this boundaryalmost overlapped the 700mm/yr annual precipitation(Ren, 1998). Thus, Zone 5 represents relatively dryconditions but probably not as cold as those of Zone 13(MIS 4). The less cold late stadial is shown in the result ofbiomization and also indicated by the study of Tsukada(1967) at Sun-Moon Lake. In comparison to present-daytemperatures, the estimated temperature was 4–5 1C lowerthan today during the late stadial and 8–10 1C lower in theearly stadial. This study confirms this estimation. Warm-temperate to subtropical conditions appeared at 22.3 and18.9 kyr BP before or within the Gramineae-prevailingdrier phase as mentioned previously.

5.6. Zone 4, 27.4–11.0 kyr BP, the late glacial

The late glacial is characterized by a rise of AP. Amongthe woody taxa, Cyclobalanopsis, Ilex, Symplocos and Salix

are of changing importance, mainly representing temperatebroadleaved and conifer mixed forests. The climaticconditions are drier and cooler than today, but warmerand wetter than before. A strong peak of monolete sporesand warm-temperate forest at 15.1 kyr BP (12,800 yr BP)indicates the warm–wet Bølling interval. At about13.0–12.5 kyr BP (10,900–10,450 yr BP) the increase ofSalix marked the beginning of cold conditions. Then Ilex

peaked at 12.1 kyr BP and Gramineae (435%) at11.8–11.6 kyr BP (10,200–10,100 yr BP). They indicate atrend from cold to less cold and then dry-cold conditions ofYounger Dryas time similar to the main trend found in thearid–semiarid transition zone of northern China (Zhou et al.,2001). According to a detailed study in the Netherlands(Hoek, 1997), the late Pleniglacial ended about radiocarbonage 12,900 yrBP (uncalibrated). From 12,900 to 12,450 yrBPis the Oldest Dryas, 12,450 to 12,100 yrBP is Bølling, 12,100to 11,900 yrBP is Older Dryas, 11,900 to 10,950yrBP isAllerød, 10,950 to 10,150 yrBP is Younger Dryas. In theToushe record, the warm interval with a peak of monoletespores at 15.1 kyrBP marked the warm–wet episodecorresponding to Bølling, while peaks of Salix andGramineae may correspond to Younger Dryas (13.0–11.6kyrBP or 10,900–10,100 yrBP). Warm-temperate tosubtropical elements increase at 11.5 kyrBP, but soon returnto temperate conditions at 11.2–11.0 kyrBP (7.18m). After11.0 kyrBP warm-temperate to subtropical forests appearedalmost continuously.

5.7. Zones 3–1 (11.0–1.8 kyr BP)

A Salix peak appeared at 11.0 kyr BP (7.07m) which justpreceded the wet phase indicated by the increase ofmonolete spores at 10.7 kyr BP (6.97m). Climatic condi-tions become subtropical/warm–wet again as indicated bylarge amounts of monolete spores, hydrophyllus herbs andan increase of Castanopsis at the expense of Ilex,Ligustrum, Symplocos and Salix. But the rise of Salix,Ilex and Symplocos again at about 9.6–9.4 kyr BP(8600–8400 yr BP) indicates a cold episode. The subtropi-cal-warm elements increased in the middle Holocene, i.e.Mallotus began to increase between 7.3 and 6.8 kyr BP(6500 and 6000 yr BP) and Glochidion increased at6.2–5.8 kyr BP (5450–090 yr BP). The higher value ofPinus—which grows far from the study site—runs parallelto the trend of the warm element Castanopsis, which mightindicate an intensified monsoon at about 6.9–6.8 kyr BP(6150–6050 yr BP). Salix peaks indicated the prevailingdeciduous forest and less warm conditions at about 11.0,9.6–9.4, 9, 7.9, 7.5, 7.2 and 7.1, 5.2 and 5.0, 4.0 and3.7 kyr BP.The most remarkable feature in the Holocene record is a

conspicuous dominance of monolete spores which indicatewet conditions. An et al. (2000) mentioned that theHolocene optimum may be represented by a wet intervalwhich is asynchronous in East Asia. There are severalintervals during the Holocene with such features especially

ARTICLE IN PRESS

Fig. 5. Detrended correspondence analysis. Mean scores for the samples

of each zone (from 20 to 1) plotted for the first two DCA axes.


before 6.8 kyr BP in present study, including 10.6–10.3,10.0–9.7, 9.5–8.5, 6.9–6.8 and 2.9–1.8 kyr BP (9300–9100,8900–8600, 8500–7700, 6000–6100 and the last 3000 yr BP).However, the record of the last 5000 yr in the alpine lakesat almost the same latitude has been discussed by theauthors elsewhere (Liew and Huang, 1994). The highervalue of NAP in the early Holocene is considered to be aresult of the enlargement of flooding areas due to earlyHolocene wet conditions (Bush, 2002), while that ofthe recent several millennia is attributed to humandisturbance.

The average score of each zone presented in the first andsecond axis of DCA (Grimm, 1997) is shown in Fig. 5. Pollentaxa involved in DCA analysis are those with percentage42%, including Pinus, Taxodiaceae, Ericaceae, Ilex, Alnus,Quercus, Cyclobalanopsis, Catanopsis, Liquidambar, Symplo-

cos, Trema, Ulmus, Ligustrum, Salix, Glochidion, Homa-

lanthus, Mallotus, Hydrangea, Tristellateia, Gymnosporia,Aizoaceae, Artemisia, Compositae, Polygonum, Ranunculus,Umbeliferae, Typha, Cyperaceae, Gramineae and Liliaceae.The similarity of Zones 6–13 may indicate cold conditionsbefore the late stadial drought; similarities among Zones 7, 9,10 and Zones 8, 11, 12 may indicate cyclic changes inhumidity during the interstadial. Large shifts occurredbetween Zones 19 and 18, 18 and 17, 16 and 15, 15 and14, and 4 and 3 indicating the abrupt change during the earlyglacial and between the late glacial and Holocene.

6. Discussion

We used a biomization technique to reconstruct pastaltitudinal vegetation of the Toushe pollen sequence. Thisallows interpretation of the magnitude of possible environ-mental changes if the site is sensitive to past ecotonechanges. For this site, especially in the Holocene, changesin prevailing biomes appear frequently (Fig. 4.2). Tempe-rate deciduous forest dominated by Alnus prevailed duringthe last glacial. The cold or cold/dry phase in the lastglacial is possibly indicated by the times when peaks of

Gramineae appeared although they are hardly recognizedin the biome reconstruction of this study. Tsuga–Picea

forest does not appear at this site during the last glacialalthough it appears during the early stadial in Sun-MoonLake located 100m higher. Thus, we believe that theboundary between Tsuga–Picea forest and Alnus forest waslocated near the Sun-Moon Lake in the early stadial (Liewand Chung, 2001).The large altitudinal range of Castanopsis pollen type is

another concern in the reconstruction of past biomes. Inthe present study, we include Castanopsis in subtropicaland warm-temperate forests, which means excluding itfrom the temperate broadleaved and conifer mixed forest.If we consider the high-growing species and includeCastanopsis-type pollen in wte1 also, with Castanopsis alsoincluded in temperate forests, we will find only a smallchange in Holocene biome reconstruction but a relativelyclear change in that of the early glacial (six samples among83 samples in Holocene, i.e. ages at about 4.8, 4.85, 4.9, 7.6,7.7 and 7.9 kyr BP will change to temperate broadleavedand conifer mixed forests; while most of Zone 17 willbecome temperate broadleaved and conifer mixed forests).Thus, the Castanopsis-dominant assemblage in early glacialis possibly like that of present subtropical/warm-temperateforests but less humid, or alternatively like parts oftemperate broadleaved and conifer mixed forests.

6.1. Maximum cooling of the last glacial

Long-term vegetational records often show the responseof local flora to climatic changes. During the last glacial,the winter monsoon intensified (Huang et al., 1997), andthe climate was relatively drier and colder than that oftoday. As mentioned above, the stadials of the last glacialare represented by Zone 13 (possibly MIS 4) and Zone 5(MIS 2) in which the early stadial (Zone 13) has the highestvalue of Alnus (460%). Surface pollen assemblages ofSalisien area show that Alnus-dominant (50%) conditionscould be found at about altitude 2250m of today’s forests.Thus, a vertical migration of 1500m could have occurredbetween the early stadial of the last glacial and theHolocene. Furthermore, in contrast to the Alnus-dominantassemblage of Zone 13 in Toushe, a contemporaneousPinus/Tsuga-dominant assemblage is found at the neigh-boring Sun-Moon Lake (Tsukada, 1967). Thus, the level ofSun-Moon Lake (750m) should represent the lowerboundary of Alnus/coniferous forest of the early glacial.Presently the boundary lies at about 2400m above sealevel. Though Taiwan’s uplift rate is generally high, thisarea is fairly stable (Chen, 2003), and vertical displacementdue to tectonism is negligible. Thus, the maximum ecotonemigration is estimated to be at least 41000m and possiblyabout 1500m; therefore, the temperature difference be-tween MIS 4 and present is 8–10 1C.The smooth sedimentation rate in this peat bog (Fig. 3)

excludes the conspicuous diastem during the LGM. Theseverity of cold conditions of the early and late stadials of


the last glacial here (Zone 5) appeared different from thoseof many other regions. As described above, Gramineaesometimes reached more than 40% and NAP prevailedduring the late stadial, which indicates drought conditionswith precipitation less than half the present level probably.However, if we compare the woody elements with the earlystadial (Zone 13, MIS 4), the late stadial shows a lowerpercentage of Alnus but higher percentage of Cyclobala-

nopsis. Thus, most of MIS 4 may have been colder thanMIS 2. The biomization results show a similar trend.Conditions of relatively higher sea level and lowerinsolation during MIS 4 than that of MIS 2 may beplausible reasons. The southward shifting ITCZ andtrade wind belt as well as the lowering of sea level duringthe late stadial (MIS 2) possibly resulted in the droughtconditions in this area, while the effect of the maximum icesheet of MIS 2 on subtropical temperature needs to beevaluated.

Many discussions have emphasized the wet intervalduring the later part (35–25 kyr BP) of MIS 3 and the EastAsia monsoon (An, 2000; Shi et al., 2001). In Europe, thereis a mild phase during MIS 3 at about 39,000–36,000 yr ago(Andel and Tzedakis, 1996), similar to the warm–wetinterval of 37–42 kyr BP characterized by remarkable sporepeaks in the present study. If they are related, then thewarm phase may have occurred not only in Asia.

6.2. Younger Dryas

The Younger Dryas was indicated by the remarkableincrease of Salix at about 13.0–12.5 kyr BP which differsfrom previous Cyclobalanopsis–Symplocos prevailing as-semblages, and culminated in the later part of this coldevent by an increase of Gramineae (435%) at11.8–11.6 kyr BP. They indicate a trend from cold to lesscold and then dry-cold conditions of Younger Dryas time,similar to the main trend found in the arid–semiaridtransition zone of northern China (Zhou et al., 2001). It isalmost synchronous with climate records from Europe(Peteet, 1995) and from Africa (Bonnefille et al., 1995). Inequatorial and northern Africa, Gasse (2000) also foundtwo drastic arid-humid transitions occurring around15–14.5 and 11.5–11 ka which correspond to the post-Bølling interstadial and post-Younger Dryas warmingevent in this study. However, at the present study site,the change of vegetation in 13.0–11.6 kyr BP is still withinthe range of temperate broadleaved and mixed coniferforest based on biomization. Thus, this cold event is notrecognizable from the results of forest change only.Nakagawa et al. (2003) described Younger Dryas in thepollen sequence of Lake Suigetsu, Japan, with about a400 yr lag compared with the Greenland ice core (Alley,1993; Mayewski et al., 1993). According to the pollendiagram of Lake Suigetsu, an increase of Fagus and adecrease of Carpinus occurred about 12,600 yr BP. Thus,the onset of Younger Dryas remains equivocal. Onepossible explanation of this age discrepancy is the

definition of magnitude of coldness for the beginning ofthe Younger Dryas.

7. Conclusion

The pollen stratigraphy from the low mountain area ofcentral Taiwan shows vegetational change across the last96,000 yr. During MIS 5 (probably 5c), the Castanopsis-dominant assemblage possibly represents a subtropicalevergreen broadleaved forest, less humid than at present,assuming that these Castanopsis are not high-growingspecies. A Salix-dominant interval follows, which istentatively correlated with MIS 5b. After that, Symplocos

and Myrica dominate; in conjunction with a high sporelevel, this indicates a subtropical forest with a wet episode.Castanopsis then prevails again. Thus at least one wetinterval existed in the early glacial (MIS 5a). The Alnus-

dominant forest replaced the preceding Castanopsis forestduring most of the last glacial. In the early stadial (MIS 4),the Alnus percentage is higher than that of the late stadial(MIS 2). A 8–10 1C lower annual temperature than atpresent and an about 1000–1500m lower boundary of theTsuga–Picea Zone/Upper Quercus Zone than at presentcharacterizes the early stadial (MIS 4). However, in MIS 2,the high value of NAP might represent a forest steppecondition; a fall in precipitation to half the present levelmight be possible. Alnus is lower but Cyclobalanopsis ishigher during the late stadial (MIS 2) than in the earlystadial (MIS 4) indicating less cold conditions than in mostof the early stadial. The generally drier conditions of theglacial stage are interrupted by an episodic warm/wetinterval around 42.2–37.0 kyr BP. Abrupt changes duringthe late glacial and Holocene are also clear. The peak ofmonolete spores at 15.1 kyr BP (12,800 yr BP) and a warm-temperate forest mark the warm–wet episode correspond-ing to the Bølling. At about 13.0–12.5 kyr BP an increase ofSalix possibly marks the onset of cold conditions. Thenafter a peak of Ilex at 12.1 kyr BP, Gramineae (435%) riseat 11.8–11.6 kyr BP which may correspond to the cold toless cold and then cold-dry phases of the Younger Dryas. Asubtropical warm period also appeared at 11.5 kyr BP asindicated by biomization. Subtropical conditions continueto prevail from 10.7 kyr BP onward. An increase of warmelements, such as Castanopsis, appeared around11.2 kyr BP and wet conditions indicated by spore peaksoccurred at about 10.7 kyr BP. Possible abrupt coldepisodes are indicated by Salix peaks at about 11.0,9.6–9.4, 7.9, 7.1, 5.2 and 5.0, 4.0 and 3.7 kyr BP.Subtropical to tropical elements such as Mallotus increasedin the mid-Holocene at about 7.3–6.8 kyr BP (except7.2 kyr BP), while Glochidion was higher between 6.2 and5.8 kyr BP, probably indicating a warmer interval when thesummer monsoon intensified. The warmest climate oc-curred at 6.9 and 6.1–5.9 kyr BP based on forest recon-struction. High early Holocene spore peaks occurred in theintervals 10.6–10.3, 10.0–9.7, 9.5–8.8, 6.9–6.8 and about2.9–1.8 kyr BP and are considered as a proxy of higher


precipitation induced by an intensifying East Asianmonsoon.

Acknowledgements

The authors are grateful to the reviewers Dr. Pavel Tarasovand Dr. John Dodson for their constructive suggestions inimproving this paper. We also wish to thank Prof. C.F. Hsiehin the Department of Lifesciences of National TaiwanUniversity and Prof. Ge Yu and Dr. B. Xue from NanjingInstitute of Geography and Limnology for their informationabout their biomization study, Dr. M.L. Hsieh and Mr. T.S.Shih for their help in the field and Mr. C.Y. Lee and B.C.Chen for their computer work during this study. Thanks arealso due to Dr. Grimm for DCA analysis using TiliaProgram. This study was funded by the National ScienceCouncil for the PAGES project.

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