Wood types and environment of the Tashkurgan region, Xinjiang, at 2500 cal yr BP, based on a record from the Ji'erzankale Necropolis

Wood types and environment of the Tashkurgan region, Xinjiang, at 2500 cal yr BP, based on a record from the Ji'erzankale Necropolis

Review of Palaeobotany and Palynology 238 (2017) 7–14 Contents lists available at ScienceDirect Review of Palaeobotany and Palynology journal homepa...

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Review of Palaeobotany and Palynology 238 (2017) 7–14

Contents lists available at ScienceDirect

Review of Palaeobotany and Palynology journal homepage: www.elsevier.com/locate/revpalbo

Wood types and environment of the Tashkurgan region, Xinjiang, at 2500 cal yr BP, based on a record from the Ji'erzankale Necropolis Hui Shen a,b, Xiaoqiang Li a,⁎, Xinying Zhou a, Xinhua Wu c, Zihua Tang d, Nan Sun e a Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China b College of Earth Science, University of Chinese Academy of Sciences, Beijing 100049, China c The Institute of Archeology, Chinese Academy of Social Sciences, Beijing 100710, China d Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China e The School of Earth Science and Resources, Chang'an University, Shaanxi 710064, China

a r t i c l e

i n f o

Article history: Received 25 December 2015 Received in revised form 2 December 2016 Accepted 3 December 2016 Available online 12 December 2016 Keywords: Tashkurgan Wood Oasis Vegetation Environment Climate

a b s t r a c t The Ji'erzankale Necropolis, dating back to 2500 cal yr BP, is located in the Tashkurgan, Xinjiang Uyghur Autonomous Region of China. Abundant wooden objects were unearthed in 2013 and 2014, including plates, fire altars, hearth boards, hand drills, wooden sticks, arrow shafts, bowls, two pieces of konghou (musical instrument) and a harp, among other things. Species identification of 70 wooden objects from 25 tombs indicates that they were crafted from at least seven different trees, namely Juniperus sp. (4), Populus sp. (15), Betula sp. (28), Salix sp. (8), Lonicera sp. (8), Elaeagnus angustifolia (1), Fraxinus syriaca (2), and four unidentified types. Based on the ecological habitats of the different species, we inferred that woodland dominated by Betula, Populus and Salix, with some associated Lonicera and Elaeagnus angustifolia, developed on the floodplain of the Tashkurgan River, with Juniperus boscage on the shady slopes of the local mountains. This vegetation community suggests that an arid/semi-arid oasis environment was extant at that time. Comparing this result with the shrubs found in today's floodplain and montane desert environment, our findings indicate that the climate of the Tashkurgan River valley was relatively humid around 2500 years ago. This probably resulted from an increase in precipitation transported to the region by the mid-latitude westerlies. © 2016 Elsevier B.V. All rights reserved.

1. Introduction The Tashkurgan region is located on the eastern Pamir Plateau in arid central Asia. It provided a gateway between East and West even before the opening of the Silk Road and thus played a significant role in early cultural and technological exchange between eastern and central Asia (Liu, 2012; Wu, 2012). Any reconstruction of the paleovegetation in this area is therefore of great importance and likely to shed light on the environmental context of early culture in central Asia (Mischke et al., 2010). As the Tashkurgan region is currently influenced by the mid-latitude westerlies and the Indian Summer Monsoon (ISM), its fragile ecosystem is highly sensitive to climate change (Owen et al., 2012; Xu et al., 2013). Knowledge of the paleovegetation and paleoenvironment on the Pamir Plateau remains controversial because the climate record is sketchy and few archeological sites have been discovered in this area (Wang, 2007). To better understand the historic cultural exchanges between the East and West, it is important to pay

⁎ Corresponding author. E-mail address: [email protected] (X. Li).

http://dx.doi.org/10.1016/j.revpalbo.2016.12.003 0034-6667/© 2016 Elsevier B.V. All rights reserved.

attention to the paleovegetation, climate change and early cultures in this region (Rudaya et al., 2009; Zhao et al., 2012). Both charcoal from incomplete combustion and wood found in dry or waterlogged conditions where micro-organic activity is weak can be taxonomically identified using their anatomical characteristics (McGinnes et al., 1974; Carcaillet, 2007; Gaillard et al., 2008). And they can be identified to the genus or species level, adding further detail to microplant fossil records (Shackleton and Prins, 1992; Cui et al., 2002; Sun and Li, 2012). These materials provide a record of ancient human exploitation of local environmental resources, as well as direct evidence of changes to the environment (Cope and Chaloner, 1980; Cui et al., 2002; Figueiral and Carcaillet, 2005; Jiang et al., 2006; Li et al., 2012; Sun et al., 2013). Archeological evidence and published historical documents indicated that a Bronze Age culture can be found in the Tashkurgan region, related to the Saka and Andronovo cultures, which were widespread across Siberia and central Asia at that time (Van Geel et al., 2004; Wang, 2007; Wu, 2012). The principal Bronze Age archeological discoveries from this area are the Xiabandi, Xiangbaobao and Ji'erzankale necropolises, from which an abundance of pottery, copper, ironware, woodware, animal and plant remains have been unearthed, well-

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preserved due to the region's dry climate (Institute of Archaeology of the Xinjiang Academy of Social Sciences, 1981; Wu, 2012). Integrated analysis of these materials provides a means to reconstruct local vegetation types, cultural exchanges and local ancient peoples' environmental adaptations. In this study, we focus on the wooden artifacts from Ji'erzankale Necropolis excavated in 2013 and 2014, which include wooden plates, bowls, sticks, hearth boards, hand drills, arrow shafts, musical instruments such as the konghou and harp, and sacrificial goods, namely fire altars. Using species identification and relative abundance, we identified wood types and environmental features in the Tashkurgan region at 2500 cal yr BP. Our results, in addition to those of previous studies, better clarify the human activity and environmental background of early cultural exchanges between East and West in the Pamir Plateau.

2. Study area The study area is located on the eastern Pamir Plateau, adjacent to Tajikistan, Afghanistan and Pakistan. The Tashkurgan Valley forms part of the orogenic belt of the western Kunlun-Karkunlun Mountains. Landforms include mountains, valleys, basins and hills, with a mean altitude of about 4600 m above sea level (asl), but reaching 5500–6100 m

asl in some areas (Owen et al., 2012; Xu et al., 2013) (Fig. 1). The mean annual temperature is 3.6 °C, with a mean temperature of 23.7 °C and −18.6 °C in the hottest and coldest months, respectively; the mean annual precipitation is 68.9 mm, while total annual evaporation can reach 2300 mm (Bahtiwar et al., 2008). Moisture from the Mediterranean Sea and Atlantic Ocean transported by the westerlies comprise the main source of precipitation, but moisture from the Arabian Sea driven by the ISM also reaches the area (Wake, 1989; Aizen et al., 2001; Owen et al., 2012; Xu et al., 2013). In addition, multi-scale topographic factors also exert some influence on microclimate over this area (Owen, 1988; Hewitt, 2005; Mischke et al., 2010). These combined influences make this area quite sensitive to climate change. The environment in this region is largely characterized by a shrubby desert ecosystem, due to its dry climate, with low precipitation and temperatures, and high altitude (Yang et al., 2007). Shrubland composed of Hippophae rhamnoides, Salix dasyclados, and Salix carmanica, or meadows dominated by Artemisia dracunculus, Carex and Triglochin palustre is present in river valleys (Xinjiang Integrated Expedition Team, 1978; Dickoré, 1995; Dickoré and Nüsser, 2000). At higher altitudes, the desert terrain is dominated by Ephedra and Sympegma regelii, with Seriphidium in the alpine desert and Stipa breviflora in the desert steppe (Editorial Board of the Vegetation Map of China, Chinese Academy of Sciences [CAS], 2001). Alpine vegetation is sparse, and

Fig. 1. Topographic map of the study area. The red triangle represents the Ji'erzankale Necropolis and the blue line indicates the Tashkurgan River.

H. Shen et al. / Review of Palaeobotany and Palynology 238 (2017) 7–14

alpine swamps and meadows are restricted to certain areas (Xinjiang Integrated Expedition Team, 1978) (Fig. 2) The Ji'erzankale Necropolis is located near the Tashkurgan River, in Qushiman village, Tashkurgan Tajik Autonomous County, Xinjiang (75°12′11″, 37°50′54″, 3050 m asl) (Fig. 2). Pottery, copper, stone tools, ironware, woodware, bone tools and glass beads were excavated in 2013 and 2014 by the Xinjiang Archeological Team of the Archeological Institute, CASS. A bamboo comb, wooden konghou and harp, glass beads, and red bronze mirror were all unearthed, representing an assemblage typical of East-West cultural exchanges (Wu, 2014). In addition, some rounded wooden fire altars were found for the first time in Xinjiang, indicating that fire veneration was probably prevalent among the local people (Shen et al., 2015). 3. Materials and methods A total of 70 wooden artifacts were collected from 25 tombs within the necropolis. Of these, 11 fire altars (Plate I, 1), one crutch (Plate I, 2), eight arrow shafts (Plate I, 3), two pieces of konghou (Plate I, 4), 30 wooden plates (Plate I, 5), four hand drills (Plate I, 6), three hearth boards (Plate I, 7), three wooden sticks, six pieces of woodware, one harp, and one wooden bowl were selected for identification.

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In order to minimize the damage to these wooden artifacts, we took a sample of ~4 cm3 from each wooden artifact for analysis. Hydrothermal softening was used in the laboratory for some highly rigid samples (Cao, 2006). First, they were placed in beakers of hot water at a temperature of 80 °C for 24 h. Second, a transverse section of each artifact was sliced off using a blade after air drying for examination through a stereomicroscope to arrive at a preliminary identification. Third, three sections (transverse, radial and tangential) were hand-made for each sample and then metal-sprayed to capture clear images via a scanning electron microscope (ZEISS MA EVO25). Fourth, the taxa were identified using their anatomical characteristics and wood anatomy atlases (Cheng et al., 1992; Zhou and Jiang, 1994; Fahn and Werker, 1986). We used AMS 14C dating from an arrow shaft from M14 and a fire altar from M15 (performed at Beta Analytic), which yielded dates of 2750–2710 cal yr BP and 2540–2355 cal yr BP, respectively. These dates indicate that the Ji'erzankale Necropolis is ~ 2500 years old (Table 1) (Shen et al., 2015). 4. Results The 70 artifact studied here were categorized by both taxonomy and tomb names (Table 2). Using the anatomical features present in the

Fig. 2. Location and vegetation of the Tashkurgan region. The red five-pointed star represents the city of Tashkurgan and the red triangle indicates the Ji'erzankale Necropolis.

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Plate I. Wooden artifacts found in the Ji'erzankale Necropolis. (1) fire altar; (2) crutch; (3) arrow shaft; (4) konghou; (5) wooden plate; (6) hand drill; (7) hearth board.

transverse, radial and tangential sections, 66 samples were identified. The other four could not be confidently identified because of deformation, and included two wooden plates from tombs M22 and M24, one wooden bowl from M33, and one fire altar from M35.

Both abundance (percentage of each species) and frequency (probability of occurrence of certain species among all tombs or wooden artifacts) indices were used in our data analysis. The 66 successfully identified wooden artifacts found in the Ji'erzankale Necropolis were

Table 1 Accelerator mass spectrometry (AMS) radiocarbon dates from the Ji'erzankale Necropolis. Tomb no.

Use

Lab no.

Sample type

δ13C

AMS age (yr BP)

Calibrated age (cal yr BP, 2σ)

M14 M15

Arrow shaft Fire altar

Beta-400296 Beta-400297

Wood Wood

−21.7 −22.3

2570 ± 30 2430 ± 30

2750–2700 2540–2355

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Table 2 The tomb names and the number of each species found in the Ji'erzankale Necropolis. Species Tomb no. M9 M11 M12 M13 M14 M15 M16 M17 M18 M22 M23 M24 M25 M27 M28 M29 M30 M31 M32 M33 M35 M41 M43 M44 M50 Total Abundance (%) Frequency (%)

Juniperus sp.

Populus sp.

Betula sp.

1 1

4

Salix sp.

Fraxinus syriaca

Elaeagnus angustifolia

Lonicera sp.

Unidentified

1

1 2

3 1

3

1

5

1 1 1

1 1

1

1 4

2

1 1 1 2 2 2

1

1 1

1

2 1 1

1

1

1

2

1 1

4 5.71 16

1

15 21.43 48

1 1 1

1 1

1

1 1

1

28 40.00 68

8 11.43 20

crafted from one of at least seven species, namely Juniperus sp. (4), Populus sp. (15), Betula sp. (28), Salix sp. (8), Lonicera sp. (8), Elaeagnus angustifolia (1), and Fraxinus syriaca (2) (Table 2). Among these wood artifacts, broadleaf species accounted for almost 90% of all selected timbers while the coniferous Juniperus sp. accounted for only 5.71% (Fig. 3). All seven identified species are relatively drought-enduring and widely distributed throughout central Asia. Populus and Salix, the dominant trees of deciduous broad-leaved forests in Xinjiang, are quite common in this area (Xinjiang Integrated Expedition Team, 1978). Associated with coniferous forests, Betula is well-adapted to cold conditions and is generally the dominant species of floodplain woodland (Xinjiang Integrated Expedition Team, 1978; Zheng and Zhang, 1989; Guo and Zheng, 2002). Juniperus, tolerant to dry and cold climates, is typically described as a shrub in Xinjiang, but can be classified as a tree in the western Kunlun Mountains where soils are rich in calcium carbonate and there is relatively high humidity (Xinjiang Integrated Expedition Team, 1978). Lonicera is common on the margins of the Picea forest or associated forests dominated by deciduous broadleaf

2 2.86 8

1 1.43 4

8 11.43 16

4 5.71 16

species other than Populus euphratica (Xinjiang Integrated Expedition Team, 1978). Both Elaeagnus angustifolia and Fraxinus syriaca can tolerate a dry climate and are mainly distributed along rivers, especially on floodplains and river terraces (Fet and Atamuradov, 1994). Most of these species are common on the Pamir Plateau today except for Fraxinus syriaca. Of all tombs, Juniperus sp. occupied a frequency of 16%, the only type of coniferous tree identified, while Betula sp. is the most common broadleaf species and accounts for 68% of the total. The next most common broadleaf species are Populus sp. (48%) and Salix sp. (20%). The Lonicera sp. made up 16% of the total, and appeared in only eight of 25 tombs. Fraxinus syriaca and Elaeagnus angustifolia were less common and respectively accounted for 8% and 4% of the total (Table 2). Correlation between abundance and frequency (SPSS 18) gave an r-value of 0.92 (p b 0.01), indicating a strong correlation, suggesting that there was no preference for particular timber types in each tomb. For fire altars, one was made from Populus sp., three from Juniperus sp., six from Betula sp. and one from an unidentified species. Wooden plates were crafted from Betula sp. (19), Populus sp. (8), and Salix sp. (1), with two plates remaining unidentified. The eight arrow shafts all came from the Lonicera sp. and the three sticks were made from the Salix sp., while two Fraxinus syriaca and one Populus sp. were used to craft the musical instruments. As for the frequency of each wood, the top three species were Populus sp., Salix sp. and Betula sp., with a frequency of 54.55%, 45.45% and 27.27%, respectively. The other four species all had a frequency of b20% (Table 3). Correlation analysis (r = 0.45, p N 0.05) suggests that there is no obvious relationship between abundance and frequency, showing that there may have been deliberate wood selection prior to crafting by local populations. 5. Discussion

Fig. 3. Percentage of broad-leaved or coniferous trees, and unidentified species.

Wood remains found in archeological sites are representative of the exploitation and utilization of the local environment by ancient populations. Not only do they shed light on human activity, but they also provide direct evidence for local paleovegetation reconstruction (Deforce

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Table 3 The wooden artifacts and their numbers in relation to the species of wood found in the Ji'erzankale Necropolis. Species Object

Juniperus sp.

Populus sp.

Betula sp.

Salix sp.

Fire altar Plate Hearth board Hand drill Arrow shaft Stick Woodware Konghou Harp Crutch Bowl

3

1 8 2 2

6 19

1

Total Abundance (%) Frequency (%)

4 5.71 18.18

1

Fraxinus syriaca

Elaeagnus angustifolia

Lonicera sp.

Unidentified 1 2

2 8

1 1

3

3 1

1 1 1

1 1 15 21.43 54.55

28 40.00 27.27

8 11.43 45.45

and Haneca, 2012; Li et al., 2012; Li et al., 2013; Hubau et al., 2013; Sun et al., 2013). Wooden artifacts, made by humans, constitute proof of wood type selection by indigenous peoples. According to analyses from various archeological sites, and ethno-archeological research, the availability of wood, in most cases, plays a vital role in deciding which type is selected. More widely distributed wood will be used more frequently than rarer types (Marquer et al., 2010; Picornell et al., 2011; Hoyo, 2012; Théry-Parisot and Henry, 2012; Henry and Théry-Parisot, 2014). In addition, site catchment analysis and the “Principle of Least Effort” model suggest that wood remains found in archeological sites are mostly derived from vegetation within a radius of ~ 5 km, or within one hour's walking distance from the site, suggesting that the identified wood types can also help establish the local paleovegetation record (Renfrew and Bahn, 1991; Shackleton and Prins, 1992). Thus, using taxonomic identification, we can reconstruct local paleovegetation patterns (Scheel-Ybert, 2000; Sun and Li, 2012). After study of the Ji'erzankale Necropolis, we find that at least seven species, including Juniperus sp., Populus sp., Betula sp., Salix sp., Lonicera sp., Elaeagnus angustifolia and Fraxinus syriaca, were used at this site, for many different purposes. All are still found in the Tashkurgan region today except for Fraxinus syriaca, which was used to make the konghou and harp (these musical instruments originated in Egypt). This species is mainly distributed in southern Europe, Anatolia, Palestine, Afghanistan and Pakistan, especially in humid mountain river valleys at altitudes between 1000 and 1500 m asl (Fet, 1994; Missouri Botanical Garden, 2011). In ‘The History of the Sui Dynasty’, both the lute and konghou originated from the west, rather than from China. Therefore, these exotic musical instruments found in the Tashkurgan region may result from cultural exchanges on the Pamir Plateau in the Bronze Age, rather than local crafting (Ma, 2004; He, 2006; Lin, 2006). Of 70 wooden artifacts, Betula was the most common wood and accounted for 40% of all samples, followed by Populus (~ 21%), and Salix (~ 11%). These three wood species comprised ~ 73% of the total for all samples. In addition, Betula, Populus and Salix were the three most frequent trees in all tombs and wooden artifacts, indicating that they were largely utilized. Furthermore, the clear correlation between abundance and frequency obtained from analysis of the relative coefficient (r = 0.92, p b 0.01) likely indicates that Betula, Populus and Salix were the most dominant and widely distributed trees in the Tashkurgan River Basin. Betula is mostly distributed in temperate zones, though sometimes found in the Arctic Circle or alpine areas of the subtropics (Jiang, 1990; Chen, 1994). In Xinjiang, Betula is mostly associated with montane coniferous Picea obovata, Picea schrenkiana or Larix sibirica forests. Generally, small-leaved forests consisting mainly of Betula and Populus are derived from and present in burnt areas on the margins of mountain coniferous forests (Xinjiang Integrated Expedition Team, 1978). In addition, deciduous broad-leaved forest dominated by Betula has developed

2 2.86 18.18

1 1.43 9.09

8 11.43 9.09

4 5.71 27.27

in the Tianshan and Karakoram mountain ranges (Xinjiang Integrated Expedition Team, 1978; Zheng and Zhang, 1989; Guo and Zheng, 2002). In valley-dominated regions, especially on the floodplains, woodland composed of Betula, Populus, Salix, Ulmus and other species are common (Wang, 1981). Our finding that Betula, Populus and Salix were most abundant and frequent in the Tashkurgan river terrace, while Picea and Larix, typical of montane coniferous forest ecosystems, were not found, suggests that vegetation in this area was characterized by floodplain woodlands 2500 years ago. Juniperus is principally a shrub or small tree and is distributed in mountainous areas in Xinjiang, as well as in some thickets and small grassland areas at the base of Picea forests and on shady mountain slopes covered by grassland. Juniperus trees can be seen growing on fine-grained soils rich in calcium carbonate and in areas where there is high relative humidity (Xinjiang Integrated Expedition Team, 1978). Only four Juniperus artifacts were excavated at the Ji'erzankale Necropolis, mostly associated with large fire altars that have wooden diameters of ~20 cm, indicating that they were probably taken from trees rather than shrubs. It is possible that Juniperus grew on the shady mountain slopes of the Tashkurgan Valley in the form of a tree around 2500 cal yr BP. Based on our analysis, the vegetation community of the Tashkurgan Valley could be described as floodplain woodland, dominated by Betula, Populus and Salix, with associated Lonicera sp. and Elaeagnus angustifolia. Some Juniperus trees likely grew on local shady mountain slopes around 2500 cal yr BP. Currently, this vegetation community is locally distributed in the river valleys of mid-altitude mountains. Using previous studies and the Chinese Virtual Herbarium to determine the habitat of Betula, Juniperus, Lonicera and Elaeagnus angustifolia, we extracted the bioclimatic pattern for each species via the Diva-Gis software, as shown in Table 4 (Bai, 2015). Using mean annual temperature data, all six species share a wide habitat distribution and are indicative of a typical temperate climate. Using mean annual precipitation data, we find that Elaeagnus angustifolia is mainly found in arid regions, while Betula mostly grows in semi-arid or humid regions. Considering the present climate Table 4 Climatic tolerance range of Betula, Juniperus, Lonicera, Elaeagnus angustifolia, Salix and Populus. Taxa

Betula Juniperus Lonicera Elaeagnus angustifolia Salix Populus

Alt (m)

MAT (°C)

MAP (mm)

Min Max

Min

Max

Min

Max

Location points

224 62 62 62

4398 4561 4493 3739

−1.29 −1.29 0.62 −1.3

16.73 13.07 24.55 13.08

118 22 22 22

1946 902 1994 517

– –

– –

−5.2 −6.3

23.8 22.1

16.4 1942.5 – 16.4 2394.5 –

86 50 39 33

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Table 5 Bronze Age cemeteries found in the Tashkurgan area. Site

Cal yr BP

Culture type

Objects

Reference

Early stage of Xiabandi Late stage of Xiabandi Xiangbaobao Ji'erzankale

3500–3300 2800–2500 2700–2400 2700–2300

Andronovo culture Xiangbaobao type Xiangbaobao type Xiangbaobao type

Copper, pottery, wood Copper, pottery, wood Copper, pottery, wood, ironware Copper, pottery, wood, ironware

Wu (2012) Wu (2012) Institute of Archaeology of the Xinjiang Academy of Social Sciences (1981) Wu (2014)

with a mean annual temperature of 3.6 °C and a mean annual precipitation of 68.9 mm, the vegetation community found to have existed in Tashkurgan at 2500 cal yr BP may indicate the presence of an arid to semi-arid oasis environment. At present, the vegetation in the Tashkurgan region is typical of that found in a shrubby desert, with sparse areas of woodland. Large areas of meadow- and shrubland-associated species are present along riverways, but Betula is absent. Sympegma regelii, Ephedra sp., Ajania pallasiana and Ceratoides latens are the main species found in the extremely arid mountains nearby (Guo and Zheng, 2002). In the mountainous area, Juniperus is not found, and the vegetation community mainly consists of desert plants. Water, as a result, plays a vital role in controlling vegetation patterns (Owen et al., 2002; Bahtiwar et al., 2008). Integrated analysis of habitat distribution conditions and the vegetation pattern characteristic of the abundant presence of trees in Tashkurgan at 2500 cal yr BP indicate a better water supply and a relatively more humid climate than found in the present. Archaeologists have unearthed a necropolis at Xiabandi, the only known Bronze Age site in Tashkurgan area that is dated to ~ 3500 cal yr BP (Kurban, 2002). However, the Xiabandi Necropolis was abandoned ~ 3300 cal yr BP and reoccupied ~ 2600 cal yr BP. Other excavated sites in this area, including Xiangbaobao and Ji'erzankale, all appeared at the same time, i.e. between 2600 and 2500 cal yr BP (Institute of Archaeology of the Xinjiang Academy of Social Sciences, 1981; Wu, 2012) (Table 5). The observed increase in archeological sites suggests that temporal wet climate conditions made it possible for ancient populations to live on the Pamir Plateau, promoting exchanges between East and West. Studies of various paleoclimatic records from the Pamir Plateau and surrounding areas have reached similar conclusions on the climatic conditions at the time. Pollen evidence from Bangong Co and Sumxi Co situated on the northwestern Qinghai-Tibetan Plateau and sediment records from Kalakuli Lake in the Pamir Plateau, reveal a relatively humid climatic period ~ 2500 cal yr BP (Fontes et al., 1993; Gasse et al., 1996; Campo et al., 1996; Liu et al., 2014). A comprehensive study of Bosten Lake suggests a relatively high water level between 3000 and 2400 cal yr BP (Mischke and Wünnemann, 2006). Seong et al. (2009) conducted an integrated analysis of glacier coverage in Muztag Ata-Kongur Shan, and found that the glacier advanced ~ 3.3 ± 0.6 kyr BP as a result of southward migration and stronger mid-latitude Westerlies. This may have led to greater winter snowfall in this area. Abundant glacial meltwater derived from increased winter snowfall potentially made it possible for floodplain woodlands dominated by Betula, Populus and Salix, with some Juniperus trees, to grow in Tashkurgan ~2500 cal yr BP. 6. Conclusion Analysis of 70 wooden artifacts found at the Ji'erzankale Necropolis suggests that the majority of woody plants belonged to seven species, i.e. Juniperus sp., Populus sp., Betula sp., Salix sp., Lonicera sp., Elaeagnus angustifolia and Fraxinus syriaca. Based on the percentages and ecological habitat analysis of each of these species, we inferred that deciduous broad-leaved woodlands dominated by Betula, Populus and Salix, with associated Lonicera and Elaeagnus angustifolia, developed on the floodplain of Tashkurgan River, with some growth of Juniperus trees on the shady mountain slopes in the area ~2500 cal yr BP.

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