Late Pleistocene montane vegetation and climate history from the Dajiuhu Basin in the western Hubei Province of Central China

    Late Pleistocene montane vegetation and climate history from the Dajiuhu Basin in the western Hubei Province of Central China Jiayi Xiao, Xiayun Xiao, Maoheng Zhang, Zhiyuan Shang, Ye Chen PII: DOI: Reference:

S0034-6667(15)00138-4 doi: 10.1016/j.revpalbo.2015.08.001 PALBO 3667

To appear in:

Review of Palaeobotany and Palynology

Received date: Revised date: Accepted date:

23 February 2014 29 July 2015 4 August 2015

Please cite this article as: Xiao, Jiayi, Xiao, Xiayun, Zhang, Maoheng, Shang, Zhiyuan, Chen, Ye, Late Pleistocene montane vegetation and climate history from the Dajiuhu Basin in the western Hubei Province of Central China, Review of Palaeobotany and Palynology (2015), doi: 10.1016/j.revpalbo.2015.08.001

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ACCEPTED MANUSCRIPT Late Pleistocene montane vegetation and climate history from the Dajiuhu Basin in the western Hubei Province of Central China

Jiangsu Key Laboratory of Environmental Change and Ecological Construction, College of

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Jiayi Xiaoa, b, c, Xiayun Xiaob,, Maoheng Zhanga, Zhiyuan Shanga, Ye Chena

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Geography Science, Nanjing Normal University, Nanjing 210023, China

State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and

Limnology, Chinese Academy of Sciences, Nanjing 210008, China

Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development

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and Application, Nanjing 210023, China

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Abstract

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A continuous 775-cm long sediment core (Core B) was collected from the Dajiuhu Basin in

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the western Shennongjia Forest Region of Central China. The core between 775 and 144 cm in depth spanning the period from 83.4 to 9.6 ka (calibrated age, throughout this study) was studied

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for pollen analysis. The high-resolution pollen record revealed the histories of the vegetation succession and climate changes from 83.4 to 9.6 ka in the mountainous regions at an altitude of approximately 1,700 m a.s.l. in Central China. The results show that five evident climate changes

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disclosed by the pollen record in Core B correspond to MIS (Marine Isotope Stage) 5a, MIS 4, MIS 3, the LGM (Last Glacial Maximum) of MIS 2, and the period from the deglacial of MIS 2 to the early Holocene, respectively. The temperature changes in the Dajiuhu Basin are consistent with the solar insolation in the Northern Hemisphere, the climate records in the Greenland and Guliya ice cores, the stalagmite and the loess. However, the precipitation changes during the late Quaternary in the study area were roughly reversed with the temperature changes in the Northern Hemisphere. Therefore, the climatic patterns from 83.4 to 9.6 ka in the Dajiuhu Basin are cold and humid conditions and warm and dry conditions, which may be caused by the middle latitude position, the humid monsoon climate, and the steep mountainous geomorphology of the study area. 

Corresponding author. Tel.: +86 25 86882146 (X.Y. Xiao); fax: +86 25 86882189. E-mail address: [email protected] (X.Y. Xiao). 1

ACCEPTED MANUSCRIPT Keywords: pollen; montane vegetation; climate change; late Pleistocene; Dajiuhu Basin

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1. Introduction

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The characteristics of the Asian monsoon climate have been evident in the eastern and middle

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eastern parts of the Qinghai-Tibet Plateau in China since the Late Quaternary, shifting between cold and dry climatic conditions during the glacial periods and warm and wet climatic conditions during the interglacial periods. Some geologic records disclosed by the lake sediments in the

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Qinghai-Tibet Plateau, the Zoige peat, and the Loess Plateau along with the drilling core of the South China Sea and the stalagmite isotope records have proven these characteristics (Shi et al.,

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2003; Zheng et al., 2002; Shen et al., 2005; Chen et al., 2003; Xiong et al., 2002; Qin et al., 2004; Wu et al., 2002; Wang et al., 2008; Sun et al., 2000). Under the background of global climatic changes during the Quaternary glacial and interglacial periods, the climatic environments

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disclosed by the interior land regions in South China should have local differences because of the

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different settings, such as mountainous regions, rivers, basin, lakes and marshes. For example, the

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subtropical mountainous regions in Central China can reduce the effects of the winter monsoon blowing southward during the winter, and hinder the warm and wet airflow from blowing northward during the summer because of the high and steep mountains. These factors cause an

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increase in the precipitation due to the lifting effect of the mountains to airflow. Because of local climatic differences, certain ancient trees survived in the “destruction” of the Quaternary glacial periods in the southern and southwestern parts of the Hubei Province (Ban and Qi, 1995), such as Davidia involucrate (a Tertiary ancient tropical plant) and a ‘living fossil’ Metasequoia glyptostroboides emerging during the Cretaceous period and becoming widely distributed during the Tertiary period in the Northern Hemisphere. These prove that the mountainous regions sheltered plants requiring warm and wet climatic conditions during the last glacial period. In order to understand the rules and patterns of climatic changes with latitude and longitude, it is necessary to disclose the ecological features in different altitudes and the regional climatic changes at key sites. These have important theoretical significance for a complete understanding of Quaternary climatic changes in low and medium latitudes in the Northern Hemisphere and the history of the 2

ACCEPTED MANUSCRIPT Asian monsoon climate. The Shennongjia Forest Region is located in the eastern border of the Qinling Mountains and the Bashan Mountains in Central China, between the provincial (or municipal) boundaries of

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Hubei, Shaanxi, and Chongqing. The altitudes in the forest region range from approximately 400

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to over 3000 m a.sl.. Because of the steep terrain and relative isolation, the region is nearly

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undisturbed by human activity. Thus, primary forest grows in the regions, and vertical vegetation belts are evident, which makes the Shennongjia Forest Region a refuge of subtropical plants in China and in the world. Therefore,

an accurate vegetation evolutionary history, especially

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documenting the shifting history of sensitive vegetation belts in the Shennongjia Forest Region, will provide a scientific basis for revealing past climatic changes in Central China.

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The Dajiuhu Basin, located in the western Shennongjia Forest Region, is a large subtropical closed inter-montane basin, rarely observed in other regions at the same latitude of the Northern

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Hemisphere. In the basin, the peat and tens of meters thick lake and marsh facies sediments have

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been deposited. Since the 1980s, this region has served as a key research site for paleovegetation and paleoenvironment studies during the late Quaternary by Chinese palynologists and other

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geological researchers (Liu, 1990; Li et al., 1992; Li, 1998; Liu et al., 2000; Liu et al., 2001a, b; Zhu et al., 2006; He, 2007; Zhao et al., 2007; Zhu et al., 2008, 2009). However, due to the restriction of access and sampling technology, these research achievements primarily concentrated

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on the paleovegetation and paleoenvironment histories since 16 ka. At the beginning of this century, paleoclimatic progress was obtained from stalagmite research in this region (Qiu et al., 2006; Xia et al., 2006; Jiang et al., 2006; Tong et al., 2007; Wang et al., 2008). Using paleoprecipitation as the entry point, the stalagmite researchers in China have enhanced the resolution of the evolution of the Asian monsoon system and global climatic changes during different time intervals since 220 ka to decade timescale, and have detected Dansgaard/Oeschger (D/O) events and other abrupt events (Tong et al., 2007; Wang et al., 2008). In addition, researchers have also attempted to establish a standardized paleoclimatic sequence over the Asian monsoon region. However, the interpretation of the stalagmite isotope remains controversial. The comparison and verification among the paleoclimatic records at different sites and in different materials will help provide convincing conclusions. Fortunately, a 775-cm long limnetic facies 3

ACCEPTED MANUSCRIPT sediment core was collected in the Dajiuhu Basin. Based on the previous studies, a high-resolution pollen analysis was performed to reconstruct the paleovegetation and paleoenvironment evolution histories from 83.4 to 9.6 ka in the Shennongjia Forest Region. Using a comparison with other

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climatic proxies, patterns and characteristics of temperature and precipitation configuration during

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different stages since 83.4 ka in the Shennongjia Forest Region were disclosed, which will

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supplement and complete the response patterns and forcing mechanisms of the regional climatic changes in different zones and in different types of topographical regions around the globe.

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2. Regional Setting

The Shennongjia Forest Region is characterized by a northern subtropical monsoon climate,

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with the geographical coordinates of 31°15′-31°57′ N, 109°56′-110°58′ E and an area of approximately 3,253 km2 (Fig. 1). The different natural vegetation belts in the subtropical and temperate zones of the monsoon region in eastern China are distributed at different altitudes. On

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the hilly lands below 800 m a.s.l., there are only small patches of evergreen broadleaved forests

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due to the reclamation and planting of economic forests. From 800 to 1,500 m a.s.l., the vegetation

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type is deciduous broadleaved and evergreen broadleaved mixed forest. The deciduous broadleaved forest is found in the medium-elevation mountains from 1,500 to 1,800 m a.s.l.. Between 1,800 and 2,600 m a.s.l., the vegetation type is conifer and broadleaved mixed forest,

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with sporadic distribution of cold coniferous plants in the upper part of the zone. In the medium-elevation and high mountains above 2,600 m a.s.l., cold and humid evergreen conifer forest is found (Fig. 2). The Dajiuhu Basin (31°34′~31°33′ N, 109°56′~110°11′ E, Fig. 1) is a karst basin surrounded by steep medium mountains ranging from 2,200 to 2,400 m a.s.l. (the highest mountain is the Bawangzhai Peak, 2,625.4 m a.s.l.). The basin is hydrologically recharged by precipitation and surface runoff from the surrounding mountains, without inflow and outflow of rivers. The sinkholes at the margin of the basin (north, northwest and south) are water outlets. In the basin, the modern natural vegetation is primarily an herbaceous community composed of Cyperaceae (e.g., Carex argyi, Carex capillacea) and Poaceae (e.g., Calamagrostis epigejos). The climate of the basin is temperate and humid. According to the local meteorological records, the mean annual 4

ACCEPTED MANUSCRIPT temperature in the Dajiuhu Basin at an altitude of 1,750 m is 7.2 ℃, with average monthly temperatures in July and January of 17.2 ℃ and -2.4 ℃, respectively. The annual precipitation is

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approximately 1,560 mm, primarily concentrated in the summer (from May to September). The

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influence of human activity on the basin and the surrounding natural ecological environment is relatively limited due to a sparse local population. At the beginning of this century, more than half

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of the area in this region was still covered by primary peat with swamp vegetation growth. 3. Material and Methods

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A continuous 775-cm long sediment core (Core B) was recovered in the northern Dajiuhu Basin using a set of impact drills (Netherland, Model: 04.19.SD) in April 2005 (31°29′28.428″ N,

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109°59′39.84″ E, altitude of 1755 m). The lithology is primarily peat and clay, and the strata description is shown in Fig. 3. The core was sectioned at 1 cm intervals, and the samples were

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stored at 0°C until analysis. Because there have been relatively many pollen studies since the

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deglacial period in the Dajiuhu Basin, we only studied the period from 83.4 to 9.6 ka (775-144 cm section of Core B). The pollen was analyzed at 2-4 cm intervals.

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The chronology of Core B was based on 5 AMS 14C dates of the pollen residues and a date determined by the amino acid racemization dating method (Zhou, 1989, Li et al., 1990). The 5 AMS 14C dates were determined at the W. M. Keck Radiocarbon Laboratory of the Department of

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Earth System Science, University of California, USA. All dates were calibrated to the calendar years prior to the present (0 BP=1950 AD) with the program CALIB 6.0 utilizing the IntCal09 calibration data set (Reimer et al., 2009). The amino acid racemization dating method employs a pre-column derivatization of the DL-amino acids with o-phthaldialdehyde (OPA) along with the chiral thiol, N-isobutyryl-L-cysteine (IBLC), to yield fluorescent diastereomeric derivatives of the chiral primary amino acids. The method was performed on an integrated Hewlett-Packard HP1100 liquid chromatograph equipped with a quaternary pump and a vacuum degasser, an auto-injector and autosampler, and an HP1046A programmable fluorescence detector at the Center Laboratory of Biology, the College of Life Science, Nanjing Normal University, China. Volumetric sub-samples (1 cm3) were prepared for the pollen analysis following the standard methods (Fagri and Iversen, 1989) by treating with 10% HCl to remove carbonate, boiling in 40% 5

ACCEPTED MANUSCRIPT HF for approximately 20 minutes to remove silicate, adding HCl solution and heating to remove floccules, and sieving over a 10 µm sieving cloth to remove the fine fraction. The samples on the sieving cloth were washed and gathered into a centrifuge tube for identification. Pollen

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identification and counting were performed under the Leitz Dialux 20 optics microscope.

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Terrestrial pollen percentages were based on a sum of pollen, excluding wet or aquatic herbs,

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whereas pollen (or spore) percentages of wet or aquatic herbs, ferns, and algae were calculated using a sum, including wet or aquatic pollen, spores and algae themselves. The data are expressed as percentage and graphed using TiliaGraph (Grimm, 1993).

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The temperature and precipitation parameters since 5 ka and 16 ka in the Dajiuhu region have been quantitatively reconstructed using the transfer function method for pollen data (He, 2007;

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Zhu et al., 2008). As an in-depth palynology study in the region, the pollen types, their percentages, and the chronology in this study can be correlated with the previous studies. Thus, we

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adapted He’s method (2007) to establish a pollen-climate transfer function. Namely, 13 arboreal

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pollen types with average percentages ≥1% (or a maximum value ≥5%) and that vary monotonously with the altitude were selected as the variables of the regression equation in this

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study. These pollen types are Pinus, Picea+Abies, evergreen oaks, Castanopsis, deciduous oaks, Betula,

Liquidambar+Juglans,

Castanea,

Carya+Myrtaceae,

Carpinus+Corylus+Alnus,

Ulmus+Salix, Acer+Tilia, and Fagus. Based on the pollen data of Liu’s 43 surface samples (1990),

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He’s 43 surface samples (2007), and this study’s 16 surface samples from different altitudes around the Dajiuhu Basin and their corresponding climatic parameters, a pollen-climate transfer function was established using the multiple linear regression method performed in the SPSS software. Applying the pollen-climate transfer function to the pollen data of Core B, the climatic parameters from 83.4 to 9.6 ka in the Dajiuhu Basin were reconstructed. 4. Results 4.1. Chronology Five AMS 14C dates for Core B are shown in Table 1. An amino acid date at a depth of 650 cm is 64838±1356 yr, and its error is approximately 2%. The sediment chronology was based on a second-degree polynomial function derived from these AMS 6

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C dates and the amino acid date

ACCEPTED MANUSCRIPT (Fig. 4). The correlation coefficient (R2) of the fitted curve is 0.9981, indicating a relatively reliable chronological framework. Based on the second-degree polynomial function, the time span of the core section from 775 to 144 cm of Core B is deduced to be from approximately 83.4 to 9.6

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ka.

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4.2. Pollen record

A total of 119 pollen and spore types were identified from 339 samples between 775 and 144 cm of Core B, which are composed of 33 trees, 35 shrubs, 24 terrestrial herbs, 8 wet or aquatic

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herbs, 16 ferns, and 3 algae. There is abundant pollen in each sample. A total of 120,647 grains of pollen and spores were counted (mean of 355 grains). The pollen assemblage is dominated by tree

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pollen percentages (average 78.8%, maximum 98.5%), followed by wet or aquatic herbs and terrestrial herb percentages (averaging 22.7% and 16.7%, respectively). The percentages of the other pollen and spore types are relatively low. Among the tree pollen types, conifer pollen is

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dominated by Abies (30.8%), and Picea, Tsuga and Pinus pollen have some percentages,

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averaging 3.9%, 5.8% and 2.7%, respectively. The deciduous broadleaved trees are primarily

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deciduous oaks (5.7%), Fagus (5.3%), Betula (1.1%), Carpinus (5.4%), Ulmus (6.2%), and Celtis (3.4%). In addition, Alnus, Pterocarya, Juglans, Liquidambar, Altingia, and Aceraceae pollen are sporadically present. The evergreen broadleaved trees are dominated by evergreen oaks (4.5%)

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and Castanopsis/Lithocarpus (0.5%). The primary components of shrub pollen are Corylus (0.9%), Rosa (0.8%), and Theaceae (0.4%). Terrestrial herb pollen is dominated by Compositae (1.2%), Artemisia (4.5%), Polygonum (6.9%), and Ranunculaceae (1.0%). Wet or aquatic herb pollen is primarily Poaceae (5.1%), Cyperaceae (16.2%), and Alisma (0.8%). Fern spore is dominated by Polypodiaceae (3.1%). In addition, algae, such as Zygnema and Pediastrum, are sporadically present. The pollen record was divided into five zones based on a visual inspection, and CONISS (constrained cluster analysis by the method of incremental sum of squares) was used to check the zone selection (Grimm, 1987). The characteristics of these pollen zones are described from bottom to top (Fig. 5). Zone DJ-1 (775-683 cm, 83.4-69.7 ka). In this zone, tree pollen percentages are high and steady (mean of 91.6%, ranging from 81.2 to 98.4%), dominated by conifer pollen percentages 7

ACCEPTED MANUSCRIPT (64.1%, 13.6-90.4%). Among conifer pollen, Abies pollen percentages are relatively high with a clear fluctuation (47.5%, 11.4-71.4%). Deciduous broadleaved pollen percentages average 26.7% with an acute fluctuation, and consist primarily of deciduous oaks (4.3%), Carpinus (4.4%),

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Ulmus (5.8%), Celtis (8.0%) and Fagus (3.0%). Pollen percentages of evergreen broadleaved trees

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(0.8%), shrubs (1.1%) and terrestrial herbs (7.3%) are relatively low. Percentages of wet or aquatic

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herb pollen dominated by Cyperaceae (12.9%) are also relatively low. The zone can be further divided into four subzones (DJ-1a to DJ-1d) according to the fluctuation of tree pollen percentages. Subzones DJ-1a (775-765 cm, 83.4-81.8 ka) and DJ-1c (725-705 cm, 76.0-72.8 ka) are

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characterized by relatively high percentages of Abies pollen and relatively low percentages of broadleaved tree pollen. The fluctuation of Cyperaceae pollen percentages is similar to

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broadleaved tree pollen percentages. Subzones DJ-1b (765-725 cm, 81.8-76.0 ka) and DJ-1d (705-683 cm, 72.8-69.7 ka) are characterized by relatively low pollen percentages of Abies and

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relatively high percentages of broadleaved tree pollen. In the two subzones, Abies pollen

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percentages fluctuate acutely with a low-high-low tendency. Zone DJ-2 (683-582 cm, 69.7-55.9 ka). Tree pollen percentages in this zone are higher and

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steadier than the previous zone (93.5%, 83.3-98.5%) with higher percentages of conifer pollen (77.4%, 56.9-93.5%). Among conifer pollen, Abies pollen percentages are highest for the entire core and are relatively steady (61.4%, 40.6-77.6%). Deciduous broadleaved pollen percentages

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clearly decrease, averaging 14.1%, which is represented by the decreases in deciduous oaks (2.3%), Carpinus (1.9%), Celtis (2.7%) and Fagus (1.6%). The percentages of the other pollen taxa have no clear changes compared with the previous zone. According to the fluctuation in tree pollen percentages, the zone can be further divided into three subzones. In Subzones DJ-2a (683-645 cm, 69.7-64.4 ka) and DJ-2c (623-582 cm, 61.4-55.9 ka), Abies pollen percentages are higher than those in Subzone DJ-2b (645-623 cm, 64.4-61.4 ka), whereas deciduous broadleaved pollen percentages are lower than those in Subzone DJ-2b. Zone DJ-3 (582-405 cm, 55.9-34.5 ka). The zone is characterized by relatively low tree pollen percentages. Among tree pollen, Abies pollen percentages markedly decrease (24.2%), and pollen percentages of deciduous broadleaved trees (25.5%) and Tsuga (8.6%) slightly increase. Terrestrial herb pollen percentages evidently increase (24.4%), dominated by Polygonum (10.0%) 8

ACCEPTED MANUSCRIPT and Artemisia (7.3%). Pollen percentages of wet or aquatic herbs are highest for the entire core (41.1%, up to 73.2%), dominated by Cyperaceae (26.9%) and Poaceae (13.5%). This zone can be further divided into three subzones. In Subzone DJ-3a (582-520 cm, 55.9-48.0 ka), tree pollen

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percentages are relatively high (74.3%, 50.8-88.1%), and pollen percentages of deciduous

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broadleaved trees (20.5%) are lower than the other two subzones. Abies pollen percentages (28.8%)

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are relatively higher than the other two subzones. Relatively high percentages of ferns (9.0%, 3.9-19.1%) are dominated by Polypodiaceae. In Subzone DJ-3b (520-420 cm, 48.0-36.1 ka), tree pollen percentages are the lowest (70.7%, 42.7-86.0%) among the three subzones, and pollen

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percentages of deciduous broadleaved trees (24.6%) and Tsuga (10.5%) increase, whereas Abies pollen percentages (22.5%) decrease. Terrestrial herb pollen percentages are relatively high

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(28.0%). Pollen percentages of wet or aquatic herbs (53.3%) dominated by Cyperaceae (32.8%) and Poaceae (20.2%) are significantly higher than the other two subzones. In Subzone DJ-3c

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(420-405 cm, 36.1-34.5 ka), tree pollen percentages are higher than the other two subzones (82.6%,

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77.5-89.9%). Pollen percentages of conifer trees decrease to 24.6% due to the decreases in Abies, Picea, and Tsuga pollen percentages. Pollen percentages of deciduous broadleaved trees are

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evidently higher than the other two subzones, averaging 54.5% with a maximum of 68.0%, due to the obvious increases in Fagus (21.0%) and Carpinus (14.1%) pollen percentages. Zone DJ-4 (405-238 cm, 34.5-17.7 ka). The characteristics of the pollen assemblage are

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similar to those of Zone DJ-1 with relatively high tree pollen percentages (87.4%, 64.0-97.5%). Among tree pollen, Abies pollen percentages increase to a mean value of 37.9% compared with Zone DJ-3. Picea pollen percentages are low, except for relatively high percentages at the bottom of the zone. Pollen percentages of deciduous broadleaved trees gradually increase from the bottom to the top of the zone (mean of 34.0%) and are represented by the increases in Fagus, Betula, Carpinus, and Ulmus pollen. Terrestrial herb pollen percentages are relatively low (9.6%), and fern spore only presents sporadically. Pollen percentages of wet or aquatic herbs dominated by Cyperaceae gradually decrease, ranging from 3.0 to 63.6%. Poaceae pollen percentages sharply decrease to a mean value of 4.6%. This zone can be further divided into seven subzones. Subzones DJ-4a (405-375 cm, 34.5-31.2 ka), DJ-4c (355-320 cm, 29.1-25.5 ka), DJ-4e (300-280 cm, 23.5-21.5 ka) and DJ-4g (270-238 cm, 20.6-17.7 ka) are characterized by relatively high Abies 9

ACCEPTED MANUSCRIPT pollen percentages, whereas in Subzones DJ-4b (375-355 cm, 31.2-29.1 ka), DJ-4d (320-300 cm, 25.5-23.5 ka) and DJ-4f (280-270 cm, 21.5-20.6 ka), Abies pollen percentages are relatively low. Zone DJ-5 (238-144cm, 17.7-9.6 ka). Compared with Zone DJ-4, tree pollen percentages in

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this zone markedly decrease (57.9%), which is represented by the rapid decrease in Abies pollen

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percentages (3.1%, 0-16.0%). Tsuga pollen percentages are relatively high, with a peak value up to

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37.9% in the middle of the zone. Pollen percentages of deciduous broadleaved trees are relatively high (36.4%) but with a tendency of gradual decrease, dominated by deciduous oaks (8.9%), Fagus (7.0%), Carpinus (4.7%), and Ulmus (6.0%). In addition, pollen percentages of

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Liquidambar (0.8%) and Aceraceae (2.8%) are highest for the entire core. Certain warm subtropical components, such as Ilex, Theaceae, Myrica, and Rhus, occurred continuously.

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Terranous herb pollen percentages increase sharply to the highest level for the entire core (30.2%), dominated by Polygonum (16.1%). Compositae (1.4%), Artemisia (3.0%), Ranunculaceae (1.2%)

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and Cruciferae (3.9%) pollen also has some percentages. Pollen percentages of wet or aquatic

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herbs evidently decrease (7.9%). The zone can be divided into three subzones, namely, Subzones DJ-5a (238-207 cm, 17.7-14.7 ka), DJ-5b (207-183 cm, 14.7-12.8 ka) and DJ-5c (183-144 cm,

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12.8-9.6 ka). In Subzones DJ-5a and DJ-5c, conifer pollen percentages are relatively low (14.9% and 10.6%, respectively), whereas pollen percentages of deciduous (43.9% and 31.3%, respectively) and evergreen broadleaved trees (11.1% and 6.9%, respectively) and fern spore

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percentages (10.8% and 11.6%, respectively) are relatively high. The subtropical components, such as Ilex, Theaceae, Myrica and Rhus, present more frequently in Subzone DJ-5c than in Subzone DJ-5a. In Subzone DJ-5b, there is a peak of conifer pollen percentages (18.8%, up to 56.7%), dominated by Tsuga. Pollen of Abies, Picea, and evergreen broadleaved taxa only appears sporadically, and fern spore percentages are low (2.8%). 4.3. Pollen-climate transfer function To establish the pollen-climate transfer function, the climatic parameters such as the mean annual temperature and mean annual precipitation were used as the functions, and the percentages of the 13 arboreal pollen types previously mentioned in the 102 surface samples were used as the variables. A stepwise regression analysis was subsequently performed in the SPSS program. The 10

ACCEPTED MANUSCRIPT criteria of the stepwise method is probability-of-F-to-enter ≦0.05 and probability-of-F-to-remove ≥0.10. The models with the maximum R values are selected to establish the regression equations.

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Namely, the model with an R value of 0.936 and an F value of 111.334 is selected for the mean

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annual temperature and the model with an R value of 0.861 and an F value of 45.457 is selected for the mean annual precipitation with significance values less than the 0.05 level. The final

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pollen-climate transfer functions are obtained as follows:

Ta=13.925-0.316X2+0.286X4-0.141X5-0.353X6-0.203X11+0.348X12

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Pa=1009.120+26.368X6+12.193X5-5.413X10+21.842X2+36.328X11-30.334X12 In these equations, Ta and Pa represent the reconstructed mean annual temperature and the

of

Pinus,

Picea+Abies,

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mean annual precipitation in the Dajiuhu region, respectively. X1, X2……X13 are the percentages evergreen

oaks,

Castanopsis,

deciduous

oaks,

Betula,

Liquidambar+Juglans, Castanea, Carya+Myrtaceae, Carpinus+Corylus+Alnus, Ulmus+Salix,

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Acer+Tilia, and Fagus, respectively.

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Pollen percentages of the 13 pollen types between 775 cm and 144 cm of Core B in the Dajiuhu Basin are substituted into the above regression equations, and the mean annual

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temperature and the mean annual precipitation during the period 83.4-9.6 ka are obtained. The quantitative reconstruction results show that the mean annual temperature generally ranged from

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-10℃ to 10℃ with a maximum value up to 20℃, and the mean annual precipitation generally ranged from 1,000 mm to 2,500 mm with a maximum value up to 2,900 mm between 83.4 and 9.6 ka. The temperature shows a negative correlation with the precipitation, i.e., a lower temperature corresponds to a higher precipitation and vice versa. To reduce the reconstruction errors, the reconstruction climatic parameter values are smoothed by a five-point running mean (Fig. 6c, d). 5. Discussion In the pollen assemblage of Core B in the Dajiuhu Basin, Abies pollen percentages are commonly greater than 40% during the periods of 83.4-69.7 ka, 69.7-55.9 ka, and 34.5-17.7 ka, below 25% between 55.9 and 34.5 ka and less than 5% during the period 17.7-9.6 ka. The study on the correlation between the surface pollen and the modern vegetation in the Shennongjia Region (Liu et al., 2001a) indicates that Picea and Abies pollen is present at an altitude of 900 m, 11

ACCEPTED MANUSCRIPT and their percentages gradually increase with elevation. At 2800 m a.s.l., Picea and Abies pollen percentages reach ~20%. Concerning the correlation between Abies pollen and its pollen source in the Shennongjia Region, Li et al. (1992) consider that Abies pollen percentages in the surface

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samples can reach up to 41% at the boundary of the Abies forest and rapidly decrease to below

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10% in the 1 km radius outside of the Abies forest. The earlier study of surface pollen in the

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Dajiuhu Basin indicates that Abies pollen percentages are relatively low (Liu, 1990). In 2007, we performed a modern vegetation investigation and a study on the relationship between the modern vegetation and the pollen rain in the Dajiuhu Basin and its surrounding mountains. The result

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shows that Picea and Abies plants grow sporadically at the mountains surrounding the basin, and Abies pollen is sporadically present in the modern pollen rain. Many studies of the relationship

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between the modern vegetation and the pollen rain in the Shennongjia Forest Region indicate that there is no Abies forest between 1700 to 1800 m a.s.l., whereas there are sporadic Abies pollen in

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the surface samples in the Shennongjia Forest Region. The pollen assemblage in this study

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indicates that the sub-alpine cold-temperate conifer forest existing in the high altitude areas of the Shennongjia Forest Region at present shifted up and down along the altitude accompanied with

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the climatic changes during the period 83.4-9.6 ka. The forest might move to the altitudes of 1700 m or even lower in the Shennongjia region. The five pollen zones of Core B reflect five different stages of vegetational succession in the

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Dajiuhu Basin (1,700 m a.s.l.). The pollen assemblage in Zone DJ-1 reflects that the constructive species of the vegetation types around the basin are alternation of Abies and deciduous broadleaved trees during the period 83.4-69.7 ka. Namely, the mountains around the Dajiuhu Basin were covered by flourishing Abies forests during the sub-periods of 83.4-81.8 ka and 76.0-72.8 ka, whereas during the sub-periods of 81.8-76.0 ka and 72.8-69.7 ka, the vegetation types around the basin were conifer and broadleaved mixed forest primarily composed of Abies, Fagus, Carpinus, Ulmus, and Celtis. The pollen assemblage in Zone DJ-2 indicates that the mountains around the Dajiuhu Basin were covered by flourishing Abies forests (even pure Abies forests) from 69.7 to 55.9 ka. The pollen assemblage in Zone DJ-3 reflects that the vegetation types around the basin were conifer and broadleaved mixed forest primarily composed of Abies, deciduous oaks, Fagus, Carpinus, and Ulmus from 55.9 to 34.5 ka. However, the broadleaved tree 12

ACCEPTED MANUSCRIPT proportion in the forest gradually increased, and the Abies proportion gradually decreased. The pollen assemblage in Zone DJ-4 implies that the vegetation during the sub-periods of 34.5-31.2 ka, 29.1-25.5 ka, 23.5-21.5 ka, and 20.6-17.7 ka was restored to Abies forests, but the vegetation types

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during the sub-periods of 31.2-29.1 ka, 25.5-23.5 ka and 21.5-20.6 ka were conifer and

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broadleaved mixed forest primarily composed of Abies, deciduous oaks, Fagus, Betula, Carpinus,

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and Ulmus. The pollen assemblage in Zone DJ-5 indicates a broadleaved forest landscape containing a small number of Tsuga and sporadic Abies between 17.7 and 9.6 ka. At present, the three vegetation types grew in different altitude mountainous regions under different temperature

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and humidity conditions in the Shennongjia Forest Region (Fig. 2) (Ban, 1980). According to the ecological characteristics of the modern vegetation in the Shennongjia regions, the Abies forest

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indicates a cold climate condition; the Abies and broadleaved tree mixed forest implies a temperate (relatively cool) climate condition; and the broadleaved forest indicates climate

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conditions similar to those in a warm temperate zone and a subtropical zone.

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In Central China, the Abies and Picea forests are mostly distributed in the altitude areas above 2,500 m in the Qinling and Bashan Mountains. The dark conifer forest dominated by Abies

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fargesii grows in the altitude areas from 2,600 to 3100 m in the forest region. The Abies fargesii and deciduous broadleaved mixed forest is distributed in the altitude areas between 2,400 and 2,600 m in the forest region (Fig. 2). Wu et al. (1980) consider that the mean annual temperature

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in the growing regions of the Picea and Abies forests was between 0℃ and 8℃, whereas the mean temperature of the coldest month was between -26℃ and -8℃, and the mean temperature of the warmest month was between 10℃ and 16℃. In addition to the temperature factor, the precipitation is generally greater than 600 (-1,000) mm, with the optimum average relative humidity between 70 and 80%. Simultaneously, according to the modern meteorological records in the Shennongjia Forest Region, the mean annual temperature in the distribution areas of the dark conifer forest (Abies fargesii forest) is approximately 1.4℃, and the mean annual temperature in the distribution areas of the conifer (Abies fargesii) and broadleaved (deciduous broadleaved) mixed forest is approximately 2.6℃ (the temperature change corresponds to the law that the mean annual temperature decreases 0.6℃ when the altitude increases 100 m in China). It is simple to 13

ACCEPTED MANUSCRIPT deduce the climatic changes since 83.4 ka from the reconstructed vegetational types based on the pollen record in the Dajiuhu Basin. Between 83.4 and 69.7 ka, the mean annual temperatures may be 3-5 ℃ lower than the

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current value, and the mean annual precipitation increased by 100 mm. The period is divided into four sub-periods according to the alternative increases of Abies and broadleaved tree pollen

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percentages. The relatively high percentages of broadleaved tree pollen during the sub-periods of 81.8-76.0 ka and 72.8-69.7 ka indicate that the environment was relatively warm, whereas the very high Abies pollen percentages during the sub-periods of 83.4-81.8 ka and 76.0-72.8 ka reflect that

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the environment was relatively cold.

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The mean annual temperatures during the periods of 69.7-55.9 ka and 34.5-17.7 ka in the Dajiuhu Basin were at least 6℃ lower than the current value (if the lower limit of the Abies fargesii forest is below 1,700 m a.s.l., the temperature might decline more), and the mean annual

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precipitations increased by at least 300 mm. The flourishing Abies forest during the period

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69.7-55.9 ka indicates that the climate was the coldest and most humid conditions since 83.4 ka with a moderately cool climatic fluctuation between 64.4 and 61.4 ka. The vegetation successions

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during the period 34.5-17.7 ka indicate that there were three climatic fluctuations towards moderately temperate conditions with a fluctuant amplitude of approximately 1℃ under the

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background of the generally cold and wet climatic conditions. The mean annual temperature from 55.9 to 34.5 ka may be ~4.8℃ lower than the current value, and the mean annual precipitation was similar to that during the period 83.4-69.7 ka. The conifer and broadleaved mixed forest with more Abies plants between 55.9 and 48.0 ka indicates that the temperature might rise more than 1℃ compared with that during the period 83.4-69.7 ka. The conifer and broadleaved mixed forest with more Abies, Tsuga and deciduous broadleaved trees between 48.0 and 36.1 ka indicates that the climate was cool and humid, and the temperature rose slightly compared with the previous sub-period. In the modern vegetational distribution of the Shennongjia Forest Region, the Fagus forest is distributed in the altitude areas between 1,800 and 2,200 m (Ban et al., 1995). Thus, the conifer and broadleaved mixed forest dominated by the Fagus plants between 36.1 and 34.5 ka implies that the temperature rose, possibly 0.5-2℃ lower 14

ACCEPTED MANUSCRIPT than the current value, and the environment was more humid. The conifer and broadleaved mixed forests with different dominant components indicate that the climate gradually changed from cool and relatively humid conditions to temperate and humid conditions from 55.9 to 34.5 ka.

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The mean annual temperature from 17.7 to 9.6 ka increased and was slightly lower than the

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current value, and the mean annual precipitation increased by <100 mm than the current value.

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The period is divided into three sub-periods. The sharp decrease in the Abies plants and the evident increase in the broadleaved trees (especially the evergreen broadleaved trees) during the sub-period 17.7-14.7 ka indicate that the climate rapidly warmed. During the sub-period 14.7-12.8

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ka, Tsuga was the dominant species, indicating that the climate changed to cool and humid conditions. Similar to the sub-period 17.7-14.7 ka, the sub-period 12.8-9.6 ka is more temperate

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with a slightly lower precipitation than the sub-period 14.7-12.8 ka. These secondary vegetational and climatic fluctuations during the five stages since 83.4 ka are clear. However, it is possible that

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the dating accuracy in this study is insufficient to accurately discuss these millennial scale climate

scale in this study.

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events. We focused our discussion on the glacial and interglacial cycles on the ten thousand years

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A comparison of the climatic parameters obtained from the transfer function with the paleoclimate changes reconstructed from the pollen assemblage shows that their change tendencies are coincident. They disclose that the climatic patterns since 83.4 ka in the Shennongjia

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Forest Region were cold-humid conditions and warm-dry conditions. A marked difference between the transfer function and the routine pollen sequence analysis is that the change amplitudes of the climatic parameters obtained from the transfer function are larger (Fig. 6). Yang (1996) has concluded that the mean annual temperature during the LGM was 7-12℃ lower than the current value in China. The oxygen isotope curves in Greenland (Johnsen et al., 2001) indicate that the temperature during the LGM was 20℃ lower than the current value, and the amplitude of the temperature changes for the D-O events reached 12-15℃ in Greenland. The curve of the mean annual temperature obtained from the transfer function in this study indicates that the mean annual temperature during the periods of 69.7-55.9 ka and 34.5-17.7 ka was approximately 5-14℃ lower than the current value in the Dajiuhu Basin, indicating that the Abies forest should decrease 15

ACCEPTED MANUSCRIPT beyond 900 m compared with the current value in the Shennongjia region, and the lower limit of the Abies forest might be at altitudes of 1,700 m or even lower. The curve of the mean annual precipitation shows that the mean annual precipitation in the Dajiuhu Basin was between 2,300

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mm and 2,500 mm during most of the periods 69.7-55.9 ka and 34.5-17.7 ka (the maximum

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annual precipitation recorded in the Shennongjia region was up to 2,900 mm), which is

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significantly higher than that during the periods of 55.9-34.5 ka and 17.7-9.6 ka. Although the precipitation changes since 83.4 ka were larger, the precipitation might have consistently been above 1,300 mm in the Dajiuhu Basin. Therefore, we can consider that the environment in the

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Dajiuhu Basin (or the mountains at approximately 1,700 m a.s.l. in Central China) has been humid since 83.4 ka, and its temperature and humidity were appropriate for the sustained growth of the

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forests. During the period, grassland, meadow or steppe with sparse trees reflecting severe cold or semi-arid climatic conditions did not develop in the study area.

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The changing amplitudes of the climatic parameters obtained from the transfer function in the

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Dajiuhu Basin are larger than that of other climatic records, which may be attributed to the large altitudinal gradient and steep mountains in the Shennongjia Forest Region, where the influence

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factors of temperature and precipitation are more complicated than the plains. He (2007) concludes that the variation amplitude of the mean annual temperature was 4-6℃, and the mean

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annual precipitation ranged from 1,400 to 1,610 mm since 5 ka in the Dajiuhu Basin. The mean annual temperature and precipitation quantitatively reconstructed based on the transfer function method in this study are relatively credible. After 17.7 ka, the amplitude of the climatic change was relatively large, which is primarily caused by the sharp decrease in the Abies pollen percentages. A comparison of the Abies pollen percentages, the temperature and precipitation curves reconstructed by the transfer function in the Dajiuhu Basin with the δ18O records in the Hulu cave in Nanjing (Wu et al., 2002), the Guliya Ice Core in China (Thompson et al., 1997), the Greenland Ice Core (Johnsen et al., 2001), the SPECMAP curve (Imbrie et al., 1984), and the solar radiation curve at 30°N (Berger and Loutre, 1991) shows that there is a significant correspondence among them (Fig. 6). The five evident climatic periods reflected by the pollen sequence of Core B correspond to MIS 5a (the late last interglacial stage), MIS 4 (the stadial of the last glacial period), 16

ACCEPTED MANUSCRIPT MIS 3 (the interstadial of the last glacial period), MIS 2 (the Last Glacial Maximum), and the transition from MIS 2 to MIS 1 (the deglacial and early Holocene period), respectively, although there is time deviation. The time deviation may be caused by dating uncertainty. Of course, it is

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also possible that there is difference in the response time to the global climate change in different

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regions during the Quaternary, due to the differences in the latitudes and longitudes, the sea and

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land locations, the geomorphic conditions, proxies, materials and methods, dating results, and the lagging times of the response of the vegetation compositions and successions to climatic changes. In general, the climate changes in the inland mountains of southern China during the period

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83.4-9.6 ka significantly respond to the global climate changes.

Since the middle Pleistocene, many palaeoclimate records in the loess, stalagmite, lake

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sediment, and ice core of the Qinghai-Tibet Plateau mostly recorded the climatic conditions with cold and dry conditions or warm and humid conditions (Li et al., 2006; Chen et al., 2003; Xiong et

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al., 2002; Shen et al., 2005; Guan et al., 2007; Qin et al., 2001; Jiang et al., 2004; Xiao et al.,

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2014a, b). According to the characteristic of the monsoon climate in China, Li (2006) has designated the region among the Yalu River estuary, the Yangtze River estuary, and Lanzhou

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Province as the monsoon climatic delta. Within the delta region, the climatic characteristics of the cold-dry conditions during the glacial period and the warm-humid conditions during the interglacial period are evident. The loess and paleosol series represent the typical climatic

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sequences in the region (Li et al., 2006). South of the delta, especially the middle and lower Yangtze River and its south, the climatic characteristics of the cold-dry conditions and the warm-humid conditions are not as evident as in the delta region. The palaeoclimate during the late Quaternary was the climatic characteristics of the cold and humid conditions and the warm and dry conditions. For example, the recent pollen study (Yue et al., 2012) in Pingnan of Fujian Province indicates a cool and moist environment during the LGM. The pollen record since ~5 ka in the Dajiuhu Basin reflects that the precipitation changes were opposite to the temperature changes. Namely, when the temperature was higher, the precipitation was lower, and vice versa (He, 2007), which coincides with the current climatic features in the Shennongjia Forest Region. The climate configuration of the temperature and precipitation in the Shennongjia Forest Region is inconsistent with the patterns of the climate change in the monsoon delta region in China. The 17

ACCEPTED MANUSCRIPT reason may be as follows: First, during the glacial period, the winter monsoon was strong, and the warm and moist air mass from the south was hindered from going northward. Therefore, the precipitation zones

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accumulated in the southern regions of China, resulting in a certain amount of precipitation during

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the glacial period in the middle of Yangtze River and its southern regions. Based on the stalagmite

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oxygen isotope records in south China, Chen (2005) considers that there was a powerful water-vapor transfer before the occurrence of the Asian summer monsoon (between March and mid-to-late May) in the interior land of southern China, and the precipitation is primarily frontal

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precipitation. The water vapor originates from the ocean of eastern China, thus the oxygen isotope values are heavier. During the outbreak period of the Asian summer monsoon (from late May to

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September), the precipitation is primarily convectional rain. Due to the northward shift of the Intertropical Convergence Zone (ITCZ), the water vapor is primarily derived from the ocean at the

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low latitude with lighter oxygen isotope values. Thus, it can be concluded that the precipitation in

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the local areas of the interior land region of southern China may be abundant and dominated by the frontal precipitation caused by the joining of the warm-wet and cold-dry air masses during the

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stages of the heavier stalagmite isotope values. Another reason is the subtropical mountain climate characteristics, which are different from the plains. For example, in the modern Shennongjia Forest Region, the precipitation is positively

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correlated with the mountain altitude, namely, the higher the altitude, the greater the precipitation. Thus, in the lower altitude regions, the temperature is higher, and the precipitation is lower. The difference in the precipitation among the different altitudes is significant. The meteorological records in the forest region (Zhu et al., 1999) show that the annual precipitations at the altitudes of 800 m, 1,200 m and 1,700 m are 1,000 mm, 1,234 mm and 1,600 mm, respectively. In Changyanwu, a region of 2,320 m a.s.l., the annual precipitation can reach 2,346 mm. According to the records of the meteorological station on the southern slope of the Shennongjia Mountains (Wuhan Institute of Botany, Chinese Academy of Science, 1980), it is calculated that the annual precipitation increases by 50 mm when the altitude increases by 100 m. Thus, we deduce that the annual precipitation at the altitude of 2200 m can reach 2,000 mm, and the annual precipitation at the summit of Shennongjia may be higher than 2,500 mm. This study and the other pollen records 18

ACCEPTED MANUSCRIPT in the Dajiuhu Basin show that the Dajiuhu region has always been covered by forest vegetation since MIS 4, indicating that the annual precipitation in the Dajiuhu region was at least 800-1,000 mm and the environment was humid.

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Wu et al. (2002) have considered that the climatic configurations of the cold and wet

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conditions and the warm and dry conditions correlate with the effective precipitation in the study

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area. When the study area has a low temperature, the environment is relatively humid due to the significant decrease in the evaporation. On the contrary, the environment is relatively arid. The study on the modern meteorological conditions in the Shennongjia Forest Region (Ma, 1999)

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shows that the mild and moist mountainous climate gives rise to a sea of clouds in Shennongjia. The altitude of cloud condensation increases gradually from winter to summer, with a general

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altitude of 1,000-1,600 m. The average altitude of the Shennongjia Forest Region is 1,600 m, facilitating the formation of the sea of clouds. Under the effects of thermodynamic and dynamic

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processes, the cloud layer continuously climbs along the sunny slope of the valley, causing the

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height of the cloud top to be uneven. Because of the wind, the sea of clouds move up and down, and often remain 2 to 3 days without being dissipated. The authors encountered heavy fog in the

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summit of Shennongjia (3,000 m above sea level) in June 2007. The sea of clouds easily causes the reduction of the temperature in the earth’s surface and creates the humid environment. The easy formation of the sea of clouds is also one of the causes of the climate patterns of the cold and

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humid conditions and the warm and dry conditions in the Shennongjia Mountains during the late Quaternary.

6. Conclusions The pollen record in Core B of the Dajiuhu Basin in the Shennongjia Forest Region reveals the histories of the vegetation succession and climate changes from 83.4 to 9.6 ka in the mountainous regions at an altitude of approximately 1,700 m in Central China. The results indicate that five evident climate changes disclosed by the pollen record correspond to MIS 5a, MIS 4, MIS 3, the LGM of MIS 2, and the period from the deglacial of MIS 2 to the early Holocene, respectively. The temperature changes in the Dajiuhu Basin were consistent with the solar insolation in the Northern Hemisphere, the climatic records in the Greenland and Guliya ice 19

ACCEPTED MANUSCRIPT cores, the stalagmite and the loess during the period 83.4-9.6 ka. However, due to the synthetic influences of the middle latitude position, the humid monsoon climate, and steep mountainous geomorphology, the precipitation is positively correlated with the altitude and negatively

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correlated with the temperature in the study area. Therefore, the precipitation changes during the

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late Quaternary in the study area were inconsistent with the precipitation changes with latitudes in

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the Northern Hemisphere. Particularly, the climatic patterns of the cold and humid conditions and the warm and dry conditions since 83.4 ka in the Dajiuhu Basin are inconsistent with the climatic patterns of the cold and dry conditions and the warm and humid conditions during the Quaternary

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in the Qinghai-Tibet Plateau, the Loess Plateau, the North China Plain and northeastern China. There are many plains or terraces in northern China, which is favorable for the cold and dry winter

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monsoon from the north and the warm and moist summer monsoon from the south going into the inland when they break out, resulting in large-scale climatic effects. However, the east-west

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orientation of Qinling and Bashan Mountains are located at the northern border of the subtropical

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regions in Central China and are controlled by the monsoon climate. Because of the steep landforms and numerous mountain peaks in the regions, the winter and summer monsoons are

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weakened when they pass through the mountains. When water vapor passes through the mountains, it is uplifted to form orographic rainfall or a sea of clouds and dense fog, resulting in the increase in the humidity in the region. This is the cause of the climate patterns of the cold and humid

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conditions and the warm and dry conditions in the mountains of southern China and the high altitude regions of the modern Shennongjia Forest Region. Therefore, under the background of the global climatic changes of the cold and dry conditions and the warm and humid conditions during the Quaternary, investigations of the specificity and difference in the environmental evolution in the local areas can more comprehensively elucidate the characteristics and laws of the climatic changes in different regions and zones.

Acknowledgments This research was financially supported by the National Natural Science Foundation of China (41072127, 41272188, 40972112, and 41373011), a Project Funded by the Priority Academic 20

ACCEPTED MANUSCRIPT Program Development of Jiangsu Higher Education Institutions, and Jiangsu Key Laboratory of Environmental Change and Ecological Construction. We thank Professor M H Stephenson and two anonymous reviewers for providing important advice that improved the quality of the manuscript.

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We also thank Assistant Professor Alice Yao (University of Chicago) for editing the manuscript

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and Dr. H.B. Lü for conducting the fieldwork.

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177-180. (in Chinese).

Zhu, C., Chen, X., Ma, C.M., Zhu, Q., Li, Z.X., Xu, W.F., 2008. Spore-pollen-climatic factor transfer function and

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paleoenvironment reconstruction in Dajiu, Shennongjia, Central China. Chinese Science Bulletin 53(Sup.), 42-49. Zhu, C., Ma, C.M., Zhang, W.Q., 2006. Sporopollen records and environmental evolution in Dajiu Lake, Shennongjia since 15.753 ka BP. Quaternary Sciences 26(5), 814-826. (in Chinese).

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Zhu, Y., Chen, Y., Zhao, Z.J., Xiao, J.Y., Zhang, M.H., Shu, Q., Zhao, H.Y., 2009. Record of environmental change

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by α-cellulose δ13C of sphagnum peat at Shennongjia, 4000-1000 a BP. Chinese Science Bulletin 54 (20), 3731-3738

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Forestry Industry Press, Beijing, 8. (in Chinese).

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ACCEPTED MANUSCRIPT Illustrations Fig. 1. The location of Core B in the Dajiuhu Basin in China.

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Fig. 2. The vertical distribution diagram of the natural vegetation and the climate characteristics in

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Shennongjia, Western Hubei Province (adapted according to Ban (1980), Local Chronicles

(1999)).

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Fig. 3. Lithology of Core B in the Dajiuhu Basin.

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Compilation Committee in Shennongjia Forest District in Hubei Province (1996), Zhu et al.

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Fig. 4. Age versus depth plot for Core B in the Dajiuhu Basin.

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Fig. 5. Pollen percentage diagram of selected taxa from the Dajiuhu Basin (Core B).

Fig. 6. Regional and global correlations from 83.4 to 9.6 ka. (a) Average summer insolation at

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30°N (Berger and Loutre, 1991). (b) Abies pollen percentages in Core B in the Dajiuhu Basin (this study). (c) Mean annual temperature reconstructed by the transfer function method in the Dajiuhu Basin (this study). (d) Mean annual precipitation reconstructed by the transfer function method in

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the Dajiuhu Basin (this study). (e) Hulu Cave δ 18O records (Wang et al., 2001), China. (f) The δ O record in the Guliya ice core, China (Thompson et al., 1997). (g) The δ 18O records from the

Greenland Ice Core Project (GRIP) (Johnsen et al., 2001). (h) The δ SPECMAP (Imbrie et al., 1984).

Table 1 AMS radiocarbon dates from Core B in the Dajiuhu Basin.

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ACCEPTED MANUSCRIPT Table 1 AMS radiocarbon dates from Core B in the Dajiuhu Basin

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Pollen residue

4355

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08C10

226

Pollen residue

13570

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16533-16919

16726

07C71

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Pollen residue

20240

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23879-24437

07C72

369

Pollen residue

24530

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08C22

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Pollen residue

35540

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Error(±yr)

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Mid-point (cal yr BP) 4914 24158

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39989-41461

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Material

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Calibrated age (cal yr BP, 2σ) 4859-4969

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ACCEPTED MANUSCRIPT Highlights A high-resolution pollen record spanning 83.4 ka in Central China was analyzed.

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Five evident climate changes disclosed by the pollen record correspond to MIS 5-2.

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The climatic patterns are cold and humid conditions and warm and dry conditions.

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The mechanism of precipitation in Central China has regional specificity.

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