Ecological Responses to Holocene Millennial-Scale Climate Change ...

5 downloads 0 Views 3MB Size Report
Mar 5, 2014 - J. Mt. Sci. (2014) 11(3): 674-687 ... Abstract: Ecosystem response to climate change in .... millennial-scale climate change in East and Central.
J. Mt. Sci. (2014) 11(3): 674-687 DOI: 10.1007/s11629-014-2980-x

e-mail: [email protected]

http://jms.imde.ac.cn

Ecological Responses to Holocene Millennial-Scale Climate Change at High Altitudes of East and Central Asia: A Case Study of Picea/Abies Pollen Changes in Lacustrine Sediments LI Yu*, ZHANG Cheng-qi, ZHOU Xue-hua College of Earth and Environmental Sciences, Center for Hydrologic Cycle and Water Resources in Arid Region, Lanzhou University, Lanzhou 730000, China *Corresponding author, e-mail: [email protected]; Tel.: 86-931-8912709: Fax: 86-931-8912712 Citation: Li Y, Zhang CQ, Zhou XH (2014) Ecological responses to Holocene millennial-scale climate change at high altitudes of east and central Asia: a case study of Picea/Abies pollen changes in lacustrine sediments. Journal of Mountain Science 11(3). DOI: 10.1007/s11629-014-2980-x

© Science Press and Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg 2014

Abstract: Ecosystem response to climate change in high-altitude regions is a focus on global change research. Picea/Abies forests are widely distributed at high altitudes of East and Central Asia, and their distribution changes are sensitive to climate change. Humidity is an important climatic factor that affects high-altitude ecosystems; however, the relationship between distribution changes of Picea/Abies forests and millennial-scale variability of humidity is still not clear. Palynological records can provide insights into millennial-scale paleovegetation changes, which have been successfully used to reconstruct past climate change in East and Central Asia. In this study, we synthesized 24 Picea/Abies pollen and humidity/moisture changes based upon Holocene lake records in East and Central Asia in order to explore the response of high-latitude ecosystem to millennial-scale climate change. The changing pattern of Holocene lacustrine Picea/Abies pollen in arid Central Asia differs from that of monsoonal East Asia, which can be due to different millennial-scale climate change patterns between monsoonal and arid Central Asia. Then, the relationship between changes in Picea/Abies pollen and humidity/moisture conditions was examined based on a comparison of pollen and humidity/moisture records. The results indicate that millennial-scale Picea/Abies distribution changes are Received: 7 January 2014 Accepted: 5 March 2014

674

mainly controlled by moisture variability at high altitudes, while the temperature effect plays a minor role in Picea/Abies distribution changes. Moreover, this research proves that lacustrine Picea/Abies pollen can be used as an indicator of millennial-scale humidity/moisture evolution at high altitudes in East and Central Asia. Keywords: Lake sediments; Palynological records; High-altitude regions; Picea/Abies; Asian summer monsoon; Millennial-scale; Climate change

Introduction High-altitude ecosystem response to climate change is becoming increasingly important in the study of ecological changes on different time scales (Cramer et al. 2001; Reuss et al. 2010; Oldfield et al. 2010; McLauchlan et al. 2013; Ilyashuk et al. 2011; Lozano-García et al. 2012; Brown et al. 2013). The distribution of high mountain vegetation is closely related to humidity/moisture conditions that are associated with the effects of altitude changes (Hamann and Wang 2006; McKenney et al. 2007; Xu et al. 2007; Aitken et al. 2008; Coops and Waring 2011; Roberts and Hamann 2012).

J. Mt. Sci. (2013) 11 (3): 674-687

Picea/Abies forests are widely distributed at high altitudes and extraordinarily sensitive to fluctuations in climate (Lebourgeois et al. 2010); however, the response mechanism of Picea/Abies forests to climate change is far from clear, which has been a hot issue in the past global change research (Dahl 1990; Sykes et al. 1996; Wimmer and Grabner 1997; Bradshaw et al. 2000; Liang et al. 2001; Zheng et al. 2001; Xu et al. 2007, 2010; Albert and Schmidt 2010; Lebourgeois et al. 2010; Dang et al. 2013). As main constructive species of modern dark coniferous forests, Picea and Abies forests basically have the same distribution in East and Central Asia, and the distribution center is in the Hengduan Mountains, the eastern QinghaiTibet Plateau. Picea forests are more droughttolerant, while Abies forests are more resistant to cold and wet conditions; therefore, Picea forests are more distributed within arid areas of northwest China (Liu et al. 2002). Many studies have been conducted on the impacts of modern interannual and decadal-scale climate change on the distribution of Picea/Abies forests (Albert and Schmidt 2010; Lebourgeois et al. 2010; Dang et al. 2013). However, few studies have been done on the long-term relationship between climate change and the distribution of Picea/Abies forests. The present paper will mainly focus on the ecological responses of Picea/Abies forests to millennial-scale climate change at high altitudes of East and Central Asia. Paleoecological and paleoclimatic studies are important in establishing baselines and are essential for determining amplitudes and rates in vegetation changes on different time scales. While modern observations typically obtain conditions for the last hundred years, the paleoecological records document biotic responses to a substantially broader range of environmental variations and provide insights into the nature of climate-vegetation interactions (Davis 1989). Lacustrine palynological records near the high altitudes serve as an indicator of past vegetation changes, which are crucial to evaluate responses of high-altitude ecosystems to natural climate variability. There are numerous lakes in the Qinghai-Tibet Plateau and its surrounding regions. A volume of work has been published regarding paleoclimate and paleovegetation changes in those lakes, which contribute to our understanding of millennial-scale climate change in East and Central

Asia (Liu et al. 2002; Herzschuh et al. 2004, 2009; Xiao et al. 2004; Zhao et al. 2007, 2009a b, 2011; Sun et al. 2007; Li et al. 2009a). Picea/Abies pollen is widely found in the Holocene lake records surrounding the Qinghai-Tibet Plateau (Herzschuh et al. 2004; Chen et al. 2006; Shen et al. 2006; Zhao et al. 2007; Rudaya et al. 2008; Li et al. 2009a b, 2011). According to modern Picea/Abies pollen distribution in topsoils, Lu et al. (2008) suggested that the Picea/Abies pollen content reaches its highest level at an altitude of 2500 to 4000 m in East Asia, where the average annual temperature is between -1°C to 10°C, and the annual precipitation is between 450 and 850 mm. Many studies have also showed that the distribution of topsoil Picea/Abies pollen is similar to the distribution of Picea/Abies forests, because of the pollen’s limited ability to spread (Chaclinskaia et al. 1965; Li 1998; Minckley and Whitlock 2000; Xu et al. 2007). The paleoclimatic significance of Picea/Abies pollen has drawn much attention since 1980s (Xu et al. 1980; Wu 1985; McLeod and MacDonald 2002; Ravazzi 2002; Bezrukova et al. 2005; Zhao et al. 2006; Xu et al. 2007, 2010; Dang et al. 2012). Many investigators found the high content of Picea/Abies pollen in sediments could imply the presence of cold climate in East Asia (Xu et al. 1980; Liu and Li 2009). Meanwhile, many studies showed that the abundance of Picea/Abies pollen can be linked to humidity/moisture conditions (The Editorial Board of Chinese Vegetation 1980; Sun et al. 1996; Zhu et al. 2001; Li et al. 2011). It is still unclear regarding the relationship between millennial-scale variability of humidity/moisture conditions and Picea/Abies pollen changes. Research in the relationship is helpful to understand the responses of Picea/Abies forests to millennial-scale humidity/moisture changes. In this paper, we synthesized 24 Holocene Picea/Abies pollen and humidity/moisture records from lake sediments near the high altitudes of East and Central Asia to investigate the millennial-scale responses of Picea/Abies forests to humidity/ moistures conditions. The study region includes various types of landforms (25° to 49° N, 81° to 132° E) (Figure 1), and the modern climate is affected by the Asian monsoon systems and the westerly winds (The Editorial Board of Physical Geography of China 1984, 1988). In Central Asia, the arid

675

J. Mt. Sci. (2013) 11(3): 674-687

Figure 1 Map showing latitudes, longitudes and elevations of East and Central Asia, including 24 lake records mentioned in this research (Table 1). The Indian and East Asia summer monsoons and the westerly winds were marked on this map. There are three changing patterns of Holocene Picea/Abies pollen in the study region. Pattern 1 (white solid circles): Picea/Abies pollen contents are relatively higher during the early and middle Holocene than those of the late Holocene; Pattern 2 (black-and-white solid circles): Picea/Abies pollen contents reach their highest values during the middle Holocene; Pattern 3 (black solid triangles): Picea/Abies pollen contents reach their lowest values during the middle Holocene.

environment is dominated by the westerly winds, while East Asia and the southern Qinghai-Tibet Plateau benefit from the Asian summer monsoon water vapor transport. Arid areas in NW China blocked by the plateau are little affected by the moist airflow from the Indian and Pacific Oceans. The average altitude of the Qinghai-Tibetan Plateau is above 4000m, where solar radiations, vegetation distribution, water vapor transport, temperatures and precipitation patterns have significant differences based on altitude effects and various terrains (Zhao 1983; Takhtajan 1988; The Editorial Board of Physical Geography of China 1984, 1988). The synthesis research is also useful to evaluate the paleoclimate significance of Picea/Abies pollen in lacustrine sediments.

1

Data and Methods The

676

criteria

for

choosing

lacustrine

Picea/Abies pollen records are as follows. (1) Modern Picea/Abies forests should be distributed in the upper reaches or the high-altitude areas of those drainage basins, in which the lake records are located. (2) Picea/Abies pollen can be found in those Holocene lake records. (3) Holocene millennial-scale chronologies should be clear and reliable, while the carbon reservoir effect should be considered. The radiocarbon ages have been calibrated to calendar years in order to facilitate a comparison between different records. (4) The Holocene lake records indicate changes in humidity/moisture conditions. Totally, we selected 24 Picea/Abies pollen records in East and Central Asia (Table 1). Most of which are located on or near the Qinghai-Tibet Plateau, and the distribution of those records is similar to the distribution of modern Picea/Abies forests. Lake records in the low-altitude areas of the Asian summer monsoon domain were not collected in this research, since Picea/Abies pollen is rarely found in those records

J. Mt. Sci. (2013) 11 (3): 674-687

Table 1 Holocene lake records from East and Central Asia, which were selected in this study. There are three changing patterns of Holocene Picea/Abies pollen in the study region. Pattern 1: Picea/Abies pollen contents are relatively higher during the early and middle Holocene than those of the late Holocene; Pattern 2: Picea/Abies pollen contents reach their highest values during the middle Holocene; Pattern 3: Picea/Abies pollen contents reach their lowest values during the middle Holocene. No. Site name

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hulun Lake Hoton Nur Ugii Nur Xingkai Lake Yili Lake Balikun Lake Boston Lake Juyanze Lake Daihai Lake Baahar Nur Zhuye Lake Sanjiaocheng Lake Hongshuihe River Midiwan Section Luanhaizi Lake Hurleg Lake Qinghai Lake Haiyuan Section Koucha Lake Zoige Lake Zigetang Lake Naleng Lake Yidun Lake Erhai Lake

Location (latitude, longitude)

49°07'N, 117°30'E 48°37'N, 88°20'E 47°46'N, 102°46'E 45°12'N, 132°30'E 43°51'N, 81°57'E 43°36'N, 92°46'E 41°57'N, 87°12'E 41°54'N, 101°51'E 40°29'N, 112°33'E 39°19'N, 109°16'E 39°03'N, 103°40'E 39°00'N, 103°20'E 38°10'N, 102°45'E 37°39'N, 108°37'E 37°35'N, 101°21'E 37°19'N, 96°54'E 36°32'N, 99°36'E 36°26'N, 105°58'E 34°01'N, 97°24'E 33°27'N, 102°38'E 32°04'N, 90°50'E 31°06'N, 99°45'E 30°17'N, 99°33'E 25°47'N, 100°12'E

(Xiao et al. 2007; Wang et al. 2008). Some records are not included due to a relatively low-resolution (Xiao et al. 2006). Picea/Abies pollen percentages and grades of humidity/moisture conditions were digitalized or analyzed in this comparative study. According to a distribution analysis of modern Picea and Abies forests, Wu (2011) found that the two forests have similar responses to modern climate change. Furthermore, Picea and Abies forests have similar modern geographic distribution (Yuan et al. 2007). In addition, Holocene Picea and Abies pollen have been given the same paleoclimatic significance in East and Central Asia (Herzschuh et al. 2004; Rudaya et al. 2008; Tao et al. 2010; Wen et al. 2010; Li et al. 2011). Thus, we did not distinguish between the two pollen (Picea and Abies pollen) in this synthesis.

Elevation (m a.s.l.)

545 2083 1332 69 928 1575 1048 892 1221 1278 1309 1325 1460 1400 3200 2809 3200 1600 4540 3467 4560 4200 4470 1974

2

Pattern

2 2 2 1 2 2 2 1 1 1 3 3 1 3 1 1 1 2 2 1 3 2 3 3

References

Wen et al. (2010) Rudaya et al. (2008) Wang et al. (2009) Wu and Shen (2010) Li et al. (2011) Tao et al. (2010) Huang (2006) Herzschuh et al. (2004) Xiao et al. (2004) Huang et al. (2009) Li et al. (2009a b) Chen et al. (2006) Zhang et al. (2000) Li et al. (2003) Herzschuh et al. (2005) Zhao et al. (2007) Liu et al. (2002) Sun et al. (2007) Herzschuh et al. (2009) Zhao et al. (2011) Herzschuh et al. (2006) Kramer et al. (2010) Shen et al. (2008) Shen et al. (2006)

Results

2.1 The changing patterns of Picea/Abies pollen Figure 2 shows Holocene Picea/Abies pollen changes from 24 lake records in East and Central Asia, plotted against calendar years. Grading scales for Picea/Abies pollen contents were divided according to percentages of Picea/Abies pollen during the Holocene. There are 6 grades regarding their contents 1~6 (1 represents the lowest level, while 6 shows the highest level) (Table 2). The grades were given to every 2000 years of the Holocene (11,500~10,000 cal yr BP, 10,000~8000 cal yr BP, 8000~6000 cal yr BP, 6000~4000 cal yr BP, 4000~2000 cal yr BP, 2000 cal yr BP~present). The Holocene is generally divided into three time

677

J. Mt. Sci. (2013) 11(3): 674-687

Figure 2 Curves indicate percentages of Picea/Abies pollen on the Holocene millennial-scale, which were plotted against calibrated radiocarbon ages. Grey bars show semi-quantitative grading scales of humid/moisture conditions according to the results described by the lake records. The numbers 0 to 4 are on behalf of grading scales of humidity/moisture conditions from arid to humid. The humidity/moisture grades are not marked for Naleng Lake and Yidun Lake, because of the unclear results.

periods: the early Holocene (11,500~8000 cal yr BP), the middle Holocene (8000~4000 cal yr BP) and the late Holocene (4000 cal yr BP~present). According to this compilation, there are three changing patterns for the Holocene Picea/Abies pollen records in East and Central Asia. First, the Picea/Abies pollen content is similar during the early and middle Holocene, which is higher than that of the late Holocene (Pattern 1). Second, the Picea/Abies pollen content reaches the highest value during the middle Holocene (Pattern 2). Third, the middle Holocene is characterized by a low Picea/Abies pollen content, while the pollen content is abundant during the early and late Holocene (Pattern 3) (Figure 3 and Table 1). Figure 3 indicates the three changing patterns of the Holocene Picea/Abies pollen contents; Table 1 shows the changing pattern for every lake. As shown in Figure 1, Holocene millennialscale lacustrine Picea/Abies pollen changing patterns imply some regularity in East and Central Asia. In the mid-latitude Asia (40°~50°N), where the modern climate is dominated by the westerly winds, most of the Picea/Abies pollen records,

678

including Hulun Lake, Hoton Nur, Ugii Nuur, Yili Lake, Boston Lake and Balikun Lake, indicate that the Picea/Abies pollen content reaches the highest value during the middle Holocene (Pattern 2). Between 40°N and 43°N (monsoon marginal regions), there are three lake records (Xingkai Lake, Juyanze Lake and Daihai Lake) indicating that Picea/Abies pollen has a relatively high content both in the early and middle Holocene (Pattern 1). Regions, which are below 40°N, are mostly affected by the Asian summer monsoon and characterized by high Picea/Abies pollen contents both during the early and middle Holocene (Pattern 1). Totally, fifteen Holocene Picea/Abies pollen records are located below 40°N, while nine of them (Baahar Nuur, Zhuye Lake, Hongshui River, Luanhaizi Lake, Hurleg Lake, Qinghai Lake, Koucha Lake, Zoige Basin and Erhai Lake) show the Pattern 1. There are seven Holocene Picea/Abies pollen records that showing the pattern 2 and the pattern 3 in the midto-low latitudes. Picea/Abies pollen in Haiyuan fluvial sediments and Naleng Lake is characterized by the highest content during the middle Holocene, while this pattern (Pattern 2) is not common in

J. Mt. Sci. (2013) 11 (3): 674-687

Table 2 Millennial-scale grading scales of Picea/Abies pollen contents for different periods of the Holocene, in which the numbers 1 to 6 are on behalf of Picea/Abies pollen contents from low to high and N/A means that Picea/Abies pollen data are not available during the period. Sites

Hulun Lake Hoton Nur Ugii Nur Xingkai Lake Yili Lake Balikun Lake Boston Lake Juyanze Lake Daihai Lake Baahar Nur Zhuye Lake Sanjiaocheng Lake Hongshuihe River Midiwan Section Luanhaizi Lake Hurleg Lake Qinghai Lake Haiyuan Section Koucha Lake Zoige Lake Zigetang Lake Naleng Lake Yidun Lake Erhai Lake

Pollen contents in different periods (cal yr BP) 11,000~ 10,000~ 800~ 6000~ 4000~ 2000~ 10,000 8000 6000 4000 2000 0

N/A 2 N/A 2 2 1 N/A 1 N/A 6 6 5 2 6 6 6 5 5 1 5 5 3 2 6

4 4 4 6 4 5 N/A 4 N/A 5 5 6 5 4 5 5 6 6 3 4 3 6 5 3

3 6 6 4 3 3 6 5 6 4 2 4 6 3 4 3 4 N/A 4 6 1 2 4 2

6 5 5 3 5 6 5 6 5 3 3 1 4 2 3 4 3 N/A 6 3 2 5 3 4

2 3 3 5 6 2 4 3 4 2 4 2 3 5 2 2 2 N/A 5 2 4 1 6 5

5 1 2 1 N/A 4 3 2 3 N/A 1 3 1 1 1 N/A 1 N/A 2 1 6 4 1 1

Figure 3 A schematic diagram showing three changing patterns of Holocene Picea/Abies pollen in East and Central Asia. Qinghai Lake and Zoige Lake belong to pattern 1; Hoton Nur and Boston Lake belong to pattern 2; Sanjiaocheng Lake and Zigetang Lake belong to pattern 3.

monsoonal Asia. Lake records from Zhuye Lake, Sanjiaocheng Lake, Zigetang Lake, Yidun Lake and Midiwan Section demonstrate a low mid-Holocene Picea/ Abies pollen content (Pattern 3), and this pattern does not exist in the regions dominated by the westerly winds. According to the research of modern pollen transport in East and Central Asia, Picea/Abies pollen is mainly transported by fluvial flows, while the pollen transported by wind is limited to the boundary of the forests (Zhu et al. 2001; Lu et al. 2010; Li et al. 2011). Various changing patterns regarding Holocene Picea/Abies pollen changes can also be influenced by pollen transport processes and locations of study sites. For example, low Picea/Abies pollen contents during the midHolocene could be affected by the study sites in the lake basins of Zhuye Lake, Sanjiaocheng Lake and Midiwan Section (Li et al. 2011). In Haiyuan Section, there is no pollen data available during the mid-to-late Holocene; therefore, the changing pattern is affected by the range of data. In the Qinghai-Tibet Plateau, altitude effects have significant impacts to plant growth, so the

679

J. Mt. Sci. (2013) 11(3): 674-687

changing patterns of Picea/Abies pollen in Zigetang Lake, Naleng Lake, Yidun Lake could be influenced by the effects of altitudes. 2.2 The relationship between changes in Picea/Abies pollen and humidity/moisture conditions

records that show a good positive correlation between Picea/Abies pollen and humidity/moisture conditions, including Hulun Lake, Hoton Nur, Ugii Nur, Xingkai Lake, Juyanze Lake, Sanjiaocheng Lake, Hongshuihe River, Midiwan Section, Luanhaizi Lake, Hurleg Lake, Qinghai Lake, Koucha Lake and Zoige Lake; these lake records are widely distributed in East and Central Asia. For other 11 lake records (Zhuye Lake, Haiyuan Section, Yidun Lake, Yili Lake, Balikun Lake, Boston Lake, Daihai Lake, Baahar Nur, Zigetang Lake, Naleng Lake and Erhai Lake), we further detected the relationship between Picea/Abies pollen and humidity/ moisture conditions. Zhuye Lake is the terminal lake of the Shiyang River drainage basin and Picea/Abies pollen in the lake sediments is mainly transported by rivers from upper reaches of the watershed (Zhu et al. 2001); previous studies have indicated that pollen assemblages from different sites of the lake basin show a lot of differences due to redistribution of pollen by lake hydrodynamics; therefore, the relationship between Picea/Abies

To explore the relationship between lacustrine Picea/Abies pollen and humidity/moisture conditions on the Holocene millennial-scale, it is needed to compare the pollen changes with the humidity/moisture grading scales. According to paleo-environment reconstruction in East and Central Asia, millennial-scale changes in humidity/moisture are mainly described by changing trends or grading scales, and not in specific humidity values. In this study, we divided the Holocene humidity/moisture conditions into 5 grades (0~4) according to proxy data, lithologies and descriptions in original reports/articles (Table 2): 0 represents the driest condition, 4 represents the most humid condition. The Holocene was divided into periods of Table 3 Millennial-scale grading scales of humidity/moisture conditions 11,500~10,000, for different periods of the Holocene, in which the numbers 0 to 4 are on 10,000~8000, behalf of humidity/moisture conditions from arid to humid and N/A 8000~6000, 6000~4000, means that humidity/moisture conditions data are not available during 4000~2000, 2000~0 (cal the period. yr BP); and for every Periods 11,000~ 10,000~ 8000~ 6000~ 4000~ 2000~ (cal yr BP) 10000 8000 6000 4000 2000 0 period, there is a Hulun Lake 1 1 3 2 0~1 1~2 corresponding semiHoton Nur 1 3 3 2 1 1 quantitative humidity/ Ugii Nur N/A 2 1~2 1 2 3 moisture grade (Table 3). Xingkai Lake 1 4 3 4 4 3~4 Figure 2 shows a Yili Lake N/A 4 3 2 1 N/A Balikun Lake 0 0~1 2 2 2 1~2 comparison of changes in Boston Lake 1 1 3 4 4 4 Holocene lacustrine Juyanze Lake 1 1 1 3 2 1 Picea/Abies pollen Daihai Lake 1 1 2~3 3 1~2 1~2 contents and humidity/ Baahar Nur 0 0 2 1~2 1 0 Zhuye Lake 3 3 3 3 2 1 moisture grades for 24 Sanjiaocheng Lake 4 4 2~3 1 1~2 2 lacustrine records in East Hongshuihe River N/A 1 3 2 1~2 N/A and Central Asia. Figure 4 Midiwan Section 1~2 2 2~3 2 2 1 indicates the different Luanhaizi Lake 4 4 3.5 3 2~3 N/A correlations on the map of Hurleg Lake 3 2 1 2 3 3 Qinghai Lake 2 1 2 2 2 1 East and Central Asia, Haiyuan Section 2 1~2 2 N/A N/A N/A which is a good display for Koucha Lake 2 1 2 3~4 3 4 regional differences Zoige Lake N/A N/A 3 2 1 N/A regarding the relationship. Zigetang Lake 3 2~3 1~2 2 1 1 As has been shown in Naleng Lake N/A N/A N/A N/A N/A N/A Yidun Lake N/A N/A N/A N/A N/A N/A Figures 2 and 4 and Tables Erhai Lake 2 3 3 N/A N/A N/A 2 and 3, there are 13 lake

680

J. Mt. Sci. (2013) 11 (3): 674-687

Figure 4 Map showing the relationship between Holocene Picea/Abies pollen percentages and humidity/moisture conditions based on 24 lake records in East and Central Asia (Table 2). Blue solid circles represent that Picea/Abies pollen percentages changes are consistent with the changes of humidity/moisture conditions. Black solid triangles indicate that there are no clear relationships between them.

pollen and humidity/moisture conditions can be influenced by pollen transportation. Furthermore, the Sanjiaocheng lake record shows a good correlation between Picea/Abies pollen and humidity/moisture conditions in a surrounding area. In Haiyuan Section, pollen data were not available since 7000 cal yr BP, which could result in the unclear relationship (Sun et al. 2007). For Yidun Lake, there is no clear description regarding humidity/moisture variability, so the relationship cannot be shown clearly. According to a comparison between Picea/Abies pollen changes and lithologies in Yili Lake, Balikun Lake, Boston Lake, Daihai Lake and Baahar Nur, depositional environments and pollen deposition processes could be reasons for the unclear relationship. Shallow lacustrine deposits, including mud and peat, can be widely found in lake sediments of arid regions, which are conductive to pollen enrichment under stable depositional environments. The five lakes, Yili Lake, Balikun Lake, Boston Lake, Daihai Lake and Baahar Nur, are all located in arid or semi-arid regions, where lake levels fluctuate frequently during the Holocene, and their

Holocene lithologies are abundant with peat or mud sediments. For example, black clayish silt is deposited during the early and middle Holocene in Yili Lake (Li et al. 2011); Balikun Lake and Boston Lake are abundant with peat sediments since the middle Holocene (Huang 2006; Tao et al. 2010); muddy sediments are deposited in Daihai Lake since the late Holocene (Xiao et al. 2004); and in Baahar Nur, the silty clay mud is formed since the middle Holocene (Huang et al. 2009). Picea/Abies pollen contents are relatively high in these peat or mud layers, compared with other layers; therefore, Picea/Abies pollen changes can be severely affected by pollen enrichment and deposition processes in shallow lacustrine deposits, and less influenced by humidity/moisture conditions. In the QinghaiTibet Plateau, evaporation is relatively low at high altitudes; therefore, Picea/Abies pollen contents from Zigetang Lake and Naleng Lake are less affected by humidity/moisture conditions because of altitude effects (Herzschuh et al. 2006). In Erhai Lake, the pollen record is influenced by human impacts since the mid-Holocene (Shen et al. 2004); as a result, the relationship between Picea/Abies 681

J. Mt. Sci. (2013) 11(3): 674-687

pollen and humidity/moisture conditions is not obvious. Generally speaking, Holocene lacustrine Picea/Abies pollen variability can be related to changes in humidity/moisture conditions in East and Central Asia.

3

Discussion

The Asian summer monsoon region and arid Central Asia belong to different climate zones according to the modern climate studies, while water vapor sources, types of precipitation and humidity characteristics between them show a lot of differences (Chen et al. 2008; Li et al. 2012). It has been found that the Holocene millennial-scale Asia summer monsoon evolution and humidity changes in arid Central Asia exhibit an out-ofphase relationship (Chen et al. 2008). The Asian summer monsoon intensity reaches its peak in the early Holocene (ca. 9.0 cal kyr BP), and begins to weaken since the mid-Holocene (ca. 6.0 cal kyr BP), but arid Central Asia is characterized by the midHolocene optimal moisture conditions (Fleitmann et al. 2003; Dykoski et al. 2005; Hu et al. 2008; Liu et al. 2008; Chen et al. 2008; Li et al. 2010). The early Holocene strong Asian summer monsoon is closely related to long-term changes of low-latitude solar radiation in the Northern Hemisphere (Berger and Loutre, 1991); however, precipitation and water vapor transport changes in arid Central Asia are mainly affected by the westerly winds, whose millennial-scale changes are lagged due to the delayed response of high-latitude ice sheets to solar radiation (Chen et al. 2008; Yang et al. 2008; Jin et al. 2012; Song 2012). The different Holocene climate change patterns between arid Central and monsoonal Asia have been confirmed by the paleoclimate models (Li et al. 2010, 2012; Jin et al. 2012). According to the synthesis of Holocene lacustrine Picea/Abies pollen records in East and Central Asia, lacustrine Picea/Abies pollen also indicate different changing patterns between monsoonal and arid Central Asia. In monsoonal Asia, Picea/Abies pollen percentages are relatively high both during the early and middle Holocene, which would have responded to millennial-scale Asian summer monsoon changes. In contrast, Picea/Abies pollen reaches the maximum value during the middle Holocene in Central Asia (above

682

40°N), and this pattern is different from that of monsoonal Asia, while the different Picea/Abies pollen changing patterns are consistent with the Holocene monsoon/moisture changing patterns between monsoonal and Central Asia. Therefore, climatic factors, including precipitation types, water vapor sources and humidity characteristics, can affect Holocene millennial-scale lacustrine Picea/Abies pollen changes in East and Central Asia. By analyzing the variation of Holocene millennial-scale lacustrine Picea/Abies pollen changes in East and Central Asia, we found that Picea/Abies pollen changes are generally affected by humidity/moisture conditions, and the changing patterns have obvious regional characteristics. In the Asian summer monsoon region and monsoon marginal regions, there are 14 lake records showing the high Picea/Abies pollen content both during the early and middle Holocene, including Xingkai Lake, Juyanze Lake, Daihai Lake, Baahar Nur, Zhuye Lake, Sanjiaocheng Lake, Hongshuihe River, Midiwan Section, Luanhaizi Lake, Hurleg Lake, Qinghai Lake, Haiyuan Section, Koucha Lake and Zoige Lake. During the early Holocene, the low-latitude insolation reaches its maximum value at about 9.0 ka; at the same time, the Asian summer monsoon precipitation belt moves to the north and results in humid climates in the monsoon region or monsoon marginal regions, which lead to the expansion of Picea/Abies forests that produce a large amount of Picea/Abies pollen in surrounding lacustrine sediments; and then, the solar insolation declines obviously since the mid-Holocene and the precipitation belt moves to the south, so that the late Holocene lacustrine Picea/Abies pollen contents are relatively low (An et al. 1993; Yang et al. 2008; Song 2012). Thus, Picea/Abies pollen can be a proxy that shows variability of humidity/moisture in the monsoon region and monsoon marginal regions. In the westerly winds domain (arid Central Asia), Holocene lacustrine Picea/Abies pollen contents reach their high values during the mid-Holocene, including Hulun Lake, Hoton Nur, Ugii Nur, Yili Lake, Balikun Lake and Boston Lake. The early Holocene moisture evolution in the westerly winds domain is less affected by the strong low-latitude insolation due to the relatively high coverage of high-latitude ice sheets, low temperatures in mid-

J. Mt. Sci. (2013) 11 (3): 674-687

latitudes and the weak North Atlantic thermohaline circulation (Koc et al. 1993; Dahl-Jensen 1998; Birks and Koc 2002; Chen et al. 2008). As a result, the early Holocene environment is still arid and the development of Picea/Abies forests is inhibited due to the low humidity, which leads to low lacustrine Picea/Abies contents. Along with the melting ice caps at high-latitudes, the rise in mid-latitude temperature and the increased SST in the North Atlantic, the mid-Holocene humidity/moisture conditions reach their highest values; and then the growth of Picea/Abies forests is promoted. In the Qinghai-Tibet Plateau, Picea/Abies pollen contents from Zigetang Lake and Naleng Lake are less sensitive to variability in humidity/moisture conditions due to altitude effects, for evaporation at high altitudes is relatively low and humidity is not the limiting factor for the growth of Picea/Abies forests. Picea/Abies forests are adapted to cold and wet environment, which are widely distributed at high altitudes in East and Central Asia (The Editorial Board of Chinese Vegetation 1980). Quantitative analysis of modern topsoil Picea/Abies pollen also indicates that the abundance of Picea/Abies pollen is controlled by humidity conditions (Sun et al. 1996). At the same time, Zhu et al. (2001) found that Picea/Abies pollen is mainly transported by rivers in the Shiyang River watershed and its percentages are closely related to humidity/moisture conditions at high altitudes. According to a basin-wide comparison of Holocene lacustrine Picea/Abies pollen contents, Li et al. (2011) also pointed out that basin-wide Picea/Abies pollen percentages are controlled by moisture levels in the upper reaches from semi-arid regions. These studies consistently showed that Picea/Abies pollen is a good indicator for high-altitude humidity/moisture conditions in Asia. However, Xu et al. (1980) have reported the Late Pleistocene Picea pollen in Weinan basin, central China, and proposed that Picea/Abies pollen can be used as an indicator of cold climate on orbital-scales (Glacial-Interglacial Cycles); meanwhile, Wu (1985) stressed the Pleistocene Picea/Abies pollen in eastern and southwestern China is an important proxy for changes in paleotemperature, and did not mention whether variability of Picea/Abies pollen can be related to changes in humidity/moisture. Furthermore, Liu

and Li (2009) also found that long-term temperature changes have significant impacts on Picea/Abies pollen contents in semi-arid regions of China. Previous studies have shown that there is still some controversy regarding the relationship between climate change and Picea/Abies pollen contents, especially on whether humidity/moisture or temperature has more impact on Picea/Abies pollen changes. According to 24 Holocene lake records selected in this research, there are 11 lake records involving temperature reconstruction (Hulun Lake, Ugii Nur, Xingkai Lake, Daihai Lake, Baahar Nur, Hongshuihe River, Luanhaizi Lake, Qinghai Lake, Zigetang Lake, Naleng Lake Erhai Lake) (Zhang et al. 2000; Xiao et al. 2004; Herzschuh et al. 2005, 2006; Shen et al. 2005, 2006; Huang et al. 2009; Kramer and Herzschuh 2009; Wang et al. 2009; Wen et al. 2009; Wu and Shen 2010). There are 5 Holocene lake records (Hulun Lake, Ugii Nur, Hongshuihe River, Qinghai Lake and Koucha Lake), in which Picea/Abies pollen changes are associated both with fluctuations in temperature and humidity/moisture conditions; however, there is no law for the distribution of the five lake records, and the relationship between temperature and Picea/Abies pollen is not obvious in other lake records (Wen et al. 2009; Wang et al. 2009; Zhang et al. 2000; Shen et al. 2005; Herzschuh et al. 2009). Therefore, further work is still needed to investigate the relationship between temperature and Picea/Abies pollen on the Holocene millennial-scale. On the other hand, Picea/Abies pollen in sediments is severely affected by pollen dispersal processes. In the Yangtze River Delta region, there is no Picea/Abies pollen found in sediments of the Tianmu Mountains, even during the Last Glacial, indicating this area is not suitable for the growth of Picea/Abies (Ren et al. 1989). But the Late Pleistocene alluvial sediments in nearby plains are abundant with Picea/Abies pollen, which can be transported by the Yangtze River from the QinghaiTibet Plateau (Chen et al. 2009). Therefore, the dispersal process of Picea/Abies pollen can affect the interpretation of its environmental significance. Moreover, with the changing climatic conditions, climatic factors that influence the growth of Picea/Abies forests can change according to altitudes (Dang et al. 2012). Modern productivity changes of Picea/Abies forests in Norway prove the

683

J. Mt. Sci. (2013) 11(3): 674-687

growth of Picea/Abies forests is controlled by various factors under different climatic conditions (Zheng et al. 2001). In addition, temperature and precipitation can have different impacts to the growth of Picea/Abies forests in different seasons (Wimmer and Grabner 1997; Liang et al. 2001). In northern Europe, increased precipitation could reduce productivity of the Picea forests according to a simulation from 1963 to 1990, but distribution changes of Picea forests are closely correlated with the average temperature of the coldest month, not related to the precipitation (Bradshaw et al. 2000; Albert and Schmidt 2010). Paleo-ecological significance of pollen data may be not consistent with each other on different time scales (Zhao 2010). The response of Picea/Abies pollen to Holocene millennial-scale climate change can differ from its response to orbital-scale or modern interannual-scale climate change. On the millennial-scale, Picea/Abies pollen mainly responds to moisture conditions in arid Central Asia and summer monsoon precipitation in monsoonal Asia; therefore, humidity/moisture conditions are a major factor that determines highaltitude ecological systems. As a result, Picea/Abies pollen can be used as a proxy showing variability of humidity/moisture conditions at high altitudes in East and Central Asia.

4

Conclusions

According to a synthesis of Holocene lacustrine Picea/Abies pollen changes from 24 lake records in East and Central Asia, we found that there are three changing patterns on the Holocene millennial-scale: high Picea/Abies pollen contents both during the early and middle Holocene, high mid-Holocene Picea/Abies pollen contents and low mid-Holocene Picea/Abies pollen contents. These three types of changes have obvious spatial differences. In mid-latitude Asia (43°N to 50°N), lacustrine Picea/Abies pollen contents reach their highest levels during the mid-Holocene; on the contrary, their contents in lake sediments from the northeast of the Qinghai-Tibet Plateau and monsoonal Asia are relatively high both in the early

and middle Holocene, and then decline since the mid-Holocene. Holocene millennial-scale Asian summer monsoon evolution and moisture changes in arid Central Asia exhibit an out-of-phase relationship, which can be a reason for the different changing patterns between monsoonal and arid Central Asia. For further investigation of the correlation between Picea/Abies pollen contents and humidity/moisture conditions, we synthesized grading scales of humidity/moisture conditions of the 24 Holocene lake records from East and Central Asia. Through a comparison between the humidity/ moisture conditions and the Picea/Abies pollen contents, it was found that most of the Picea/Abies pollen changes can be related to variability of the humidity/moisture conditions; meanwhile, pollen enrichment in swamps, human activities and altitude effects in the Qinghai-Tibet Plateau can act on the Holocene millennial-scale lacustrine Picea/Abies pollen changes. On different time scales, distribution changes of Picea/Abies forests respond to climate change in different ways, and the responses are also controlled by physical geographic and climatic conditions of the study areas. Based on the results of this study, Holocene millennial-scale Picea/Abies forests changes are mainly affected by humidity/moisture fluctuations at high altitudes of East and Central Asia. As a result, lacustrine Picea/Abies pollen can be used as a proxy showing millennial-scale evolution of high-altitude humidity/ moisture conditions; furthermore, lacustrine Picea/Abies pollen can also be used in reconstruction of high-altitude precipitation due to a low high-altitude evaporation rate.

Acknowledgements This research was supported by the National Natural Science Foundation of China (Grant No. 41371009) the Fundamental Research Fund for the Central Universities of China (Grant No. lzujbky2013-127). We thank the editor and reviewers for their constructive comments and suggestions for improving this paper.

References Aitken SN, Yeaman S, Holliday JA, et al. (2008) Adaptation,

684

migration or extirpation: climate change outcomes for tree

J. Mt. Sci. (2013) 11 (3): 674-687

populations. Evolutionary Applications 1: 95-111. DOI: 10.1111/j.1752-4571.2007.00013.x Albert M, Schmidt M (2010) Climate-sensitive modelling of siteproductivity relationships for Norway spruce (Picea abies (L.)Karst.) and common beech (Fagussylvatica L.). Forest Ecology and Management 259: 739-749. DOI: 10.1016/ j.foreco.2009.04.039 An ZS, Potter S, Wu XH, et al. (1993) The Holocene climatic optimum and East Asian monsoon transition in east and central China. Chinese Science Bulletin 38: 1302-1305 (In Chinese) Berger A, Loutre MF (1991) Insolation values for the climate of the last 10,000,000 years. Quaternary Science Reviews 10: 297-317. DOI: 10.1016/0277-3791(91)90033-Q Bezrukova EV, Abzaeva AA, Letunova PP, et al. (2005) Postglacial history of Siberian spruce (Picea obovata) in the Lake Baikal area and the significance of this species as a paleoenvironmental indicator. Quaternary International 136: 47-57. DOI: 10.1016/j.quaint.2004.11.007 Birks CJA, Koc N (2002) A high-resolution diatom record of late- Quaternary sea-surface temperatures and oceanographic conditions from the eastern Norwegian Sea. Boreas 31: 323344. DOI: 10.1111/j.1502-3885.2002.tb01077.x Blois JL, Williams JW, Grimm EC, et al. (2011) A methodological framework for assessing and reducing temporal uncertainty in paleovegetation mapping from lateQuaternary pollen records. Quaternary Science Reviews 30: 1926-1939. DOI: 10.1016/j.quascirev.2011.04.017 Bradshaw RH, Holmqvist BH, Cowling SA, et al. (2000) The effects of climate change on the distribution and management of Picea abies in southern Scandinavia. Canadian Journal of Forest Research 30: 1992-1998. DOI: 10.1139/x00-130 Brown AG, Hatton J, Selby KA, et al. (2013) Multi-proxy study of Holocene environmental change and human activity in the Central Apennine Mountains, Italy. Journal of Quaternary Science 28: 71-82. DOI: 10.1002/jqs.2591 Chaclinskaia EL (1965) An Introduction to Pollen and Spore Analysis (translated by Lin Ce, et al). China Industry Press, Beijing, China. pp 1-47. (In Chinese) Chen FH, Cheng B, Zhao Y, et al. (2006) Holocene environmental change inferred from a high-resolution pollen record, Lake Zhuyeze, arid China. Holocene 16: 675-684. DOI: 10.1191/0959683606hl951rp Chen J, Wang ZH, Li X, et al. (2009) Provenance of Picea and Abies pollens in late Quaternary sediments of the Yangtze River delta. Quaternary Science 29: 290-298 (In Chinese) Coops NC, Waring RH (2011) A process-based approach to estimate lodgepole pine (Pinus contorta Dougl.) distribution in the Pacific Northwest under climate change. Climatic Change 105: 313-328. DOI: 10.1007/s10584-010-9861-2 Cramer W, Bondeau A, Woodward FI, et al. (2001) Global response of terrestrial ecosystem structure and function to CO2 and climate change: results from six dynamic global vegetation models. Global change biology 7: 357-373. DOI: 10.1046/j.1365-2486.2001.00383.x Dahl E (1990) Probable effects of climatic change due to the greenhouse effect on plant productivity and survival in North Europe. Effects of Climate Change on Terrestrial Ecosystems 4: 7-18. Dahl-Jensen D, Mosegaard K, Gundestrup N, et al. (1998) Past temperatures directly from the Greenland ice sheet. Science 282: 268-271. DOI: 10.1126/science.282.5387.268 Dang HS, Zhang YJ, Zhang KR, et al. (2013) Climate-growth relationships of subalpine fir (Abies fargesii) across the altitudinal range in the Shennongjia Mountains, central China. Climatic Change 117: 903-917. DOI: 10.1007/s10584-0120611-5 Davis MB (1989) Insights from paleoecology on global change. Bulletin of the Ecological Society of America 70: 222-228. Dykoski CA, Edwards RL, Cheng H, et al. (2005) A highresolution, absolute-dated Holocene and deglacial Asian monsoon record from Dongge Cave, China. Earth and

Planetary Science Letters 233: 71-86. DOI: 10.1016/j.epsl. 2005.01.036 Fleitmann D, Burns SJ, Mudelsee M, et al. (2003) Holocene forcing of the Indian monsoon recorded in a Stalagmite from southern Oman. Science 300: 1737-1739. DOI: 10.1126/ science.1083130 Hamann A, Wang T (2006) Potential effects of climate change on ecosystem and tree species distribution in British Columbia. Ecology 87: 2773-2786. DOI: 10.1890/0012-9658 (2006)87[2773:PEOCCO]2.0.CO;2 Herzschuh U, Tarasov P, Wünnemann B, et al. (2004) Holocene vegetation and climate of the Alashan Plateau, NW China, reconstructed from pollen data. Palaeogeography Palaeoclimatology Palaeoecology 211: 1-17. DOI: 10.1016/ j.palaeo.2004.04.001 Herzschuh U, Zhang CJ, Mischke S, et al. (2005) A late Quaternary lake record from the Qilian Mountains (NW China), evolution of the primary production and the water depth reconstructed from macrofossil, pollen, biomarker, and isotope data. Global Planet Change 46: 361-379. DOI: 10.1016/j.gloplacha.2004.09.024 Herzschuh U, Winter K, Wünnemann B, et al. (2006). A general cooling trend on the central Tibetan Plateau throughout the Holocene recorded by the Lake Zigetang pollen spectra. Quaternary International 154: 113-121. DOI: 10.1016/j. quaint.2006.02.005 Herzschuh U, Kramer A, Mischke S, et al. (2009) Quantitative climate and vegetation trends since the late glacial on the northeastern Tibetan Plateau deduced from Koucha Lake pollen spectra. Quaternary Research 71: 162-171. DOI: 10.1016/j.yqres.2008.09.003 Hu CY, Henderson GM, Huang JH, et al. (2008) Quantification of Holocene Asian monsoon rainfall from spatially separated cave records. Earth and Planetary Science Letters 266: 221232. DOI: 10.1016/j.epsl.2007.10.015 Huang XZ (2006) Holocene climate variability of arid central Asia documented by Bosten Lake, Xinjiang, China. PhD Dissertation, Lanzhou University, Lanzhou, China. pp 1-178 (In Chinese). Huang CQ, Feng ZD, Ma YZ, et al. (2009) Holocene palaeoenvironment changes recorded by pollen of Baahar Nuur Lake. Journal of Lanzhou University (Natural Science) 45: 7-12 (In Chinese) Ilyashuk EA, Koinig KA, Heiri O, et al. (2011) Holocene temperature variations at a high-altitude site in the Eastern Alps: a chironomid record from Schwarzsee ob Sölden, Austria. Quaternary Science Reviews 30: 176-191. DOI: 10.1016/j.quascirev.2010.10.008 Jin L, Chen F, Morrill C, et al. (2012) Causes of early Holocene desertification in arid central Asia. Climate Dynamic 38: 15771591. DOI: 10.1007/s00382-011-1086-1 Koc N, Jansen E, Haflidason H (1993) Paleoceanographic reconstructions of surface ocean conditions in the Greenland, Iceland and Norwegian seas through the last 14 ka based on diatoms. Quaternary Science Reviews 12: 115-140. DOI: 10.1016/0277-3791(93)90012-B Kramer A, Herzschuh U, Mischke S, et al. (2010) Holocene treeline shifts and monsoon variability in the Hengduan Mountains (southeastern Tibetan Plateau), implications from palynological investigations. Palaeogeography Palaeoclimatology Palaeoecology 286: 23-41. DOI: 10.1016/ j.palaeo.2009.12.001 Lebourgeois F, Rathgeber CB, Ulrich E (2010) Sensitivity of French temperate coniferous forests to climate variability and extreme events (Abies alba, Picea abies and Pinus sylvestris). Journal of Vegetation Science 21: 364-376 DOI: 10.1111/j. 1654-1103.2009.01148.x Li WY (1998) Quaternary Vegetation and Environment in China. Science Press, Beijing, China. pp 8-16. (In Chinese) Li XQ, Zhou WJ, An ZS, et al. (2003) The vegetation and monsoon variations at the desert-boess transition belt at Midiwan in northern China for the last 13 ka. Holocene 13:

685

J. Mt. Sci. (2013) 11(3): 674-687

779-784. DOI: 10.1191/0959683603hl664rr Li XQ, Zhao KL, Dodson J, et al. (2011) Moisture dynamics in central Asia for the last 15 kyr: new evidence from Yili Valley, Xinjiang, NW China. Quaternary Science Reviews 30: 34573466. DOI: 10.1016/j.quascirev.2011.09.010 Li Y, Wang N, Cheng H, Long H, et al. (2009a) Holocene environmental change in the marginal area of the Asian monsoon: a record from Zhuye Lake, NW China. Boreas 38: 349-361. DOI: 10.1111/j.1502-3885.2008.00063.x Li Y, Wang N, Morrill C, et al. (2009b) Environmental change implied by the relationship between pollen assemblages and grain-size in N.W. Chinese lake sediments since the Late Glacial. Review of Palaeobotany and Palynology 154: 54-64. DOI: 10.1016/j.revpalbo.2008.12.005 Li Y, Wang N, Li ZL, et al. (2011) Holocene palynological records and their responses to the controversies of climate system in the Shiyang River drainage basin. Chinese Science Bulletin 56: 535-546. DOI: 10.1007/s11434-010-4277-y Li Y, Morrill C (2010) Multiple factors causing Holocene lake– level change in monsoonal and arid central Asia as identified by model experiments. Climate Dynamic 35: 1119-1132. DOI: 10.1007/s00382-010-0861-8 Li Y, Wang N, Chen H, et al. (2012) Tracking millennial-scale climate change by analysis of the modern summer precipitation in the marginal regions of the Asian monsoon. Journal Asian Earth Science 58: 78-87. DOI: 10.1016/j. jseaes.2012.07.001 Li Y, Morrill C (2013) Lake levels in Asia at the Last Glacial Maximum as indicators of hydrologic sensitivity to greenhouse gas concentrations. Quaternary Science Reviews 60: 1-12. DOI: 10.1016/j.quascirev.2012.10.045 Liang E, Shao X, Hu Y, et al. (2001) Dendroclimatic evaluation of climate-growth relationships of Meyer spruce (Picea meyeri) on a sandy substrate in semi-arid grassland, north China. Trees 15: 230-235. DOI: 10.1007/s004680100097 Liu HY, Li YY (2009) Pollen indicators of climate change and human activities in the semi-arid region, Acta Palaeontologica Sinica 48: 211-221. (In Chinese) Liu X, Shen J, Wang SM, et al. (2002) A 16000-year pollen record of Qinghai Lake and its paleoclimate and paleoenvironment. Chinese Science Bulletin 47: 1931-1936. Liu X, Herzschuh U, Shen J, et al. (2008) Holocene environmental and climatic changes inferred from Wulungu Lake in northern Xinjiang, China. Quaternary Research 70: 412-425. DOI: 10.1016/j.yqres.2008.06.005 Liu ZL, Fang JY, Piao SL (2002) Geographical distribution of species in genera Abies, Picea and Larix in China. Acta Geographica Sinica 57: 577-586 (In Chinese) Lozano-García S, Torres-Rodríguez E, Ortega B, et al. (2012) Ecosystem responses to climate and disturbances in western central Mexico during the late Pleistocene and Holocene. Palaeogeography Palaeoclimatology Palaeoecology 370: 184195. Lu HY, Wu NQ, Yang XD, et al. (2008) Spatial pattern of Abies and Picea surface pollen distribution along the elevation gradient in the Qinghai-Tibetan Plateau and Xinjiang, China. Boreas 37: 254-262. DOI: 10.1111/j.1502-3885.2007.00019.x McKenney DW, Pedlar JH, Lawrence K, et al. (2007) Potential impacts of climate change on the distribution of North American trees. Bioscience 57: 939-948. DOI: 10.1641/ B571106 McLauchlan KK, Lascu I, Myrbo A, et al. (2013) Variable ecosystem response to climate change during the Holocene in northern Minnesota, USA. Geological Society of America Bulletin 125: 445-452. DOI: 10.1130/B30737.1 McLeod T, MacDonald G (2002) Postglacial range expansion and population growth of Picea mariana, Picea glauca and Pinus banksiana in the western interior of Canada. Journal of Biogeography 24: 865-881. DOI: 10.1046/j.1365-2699.1997. 00151.x Minckley T, Whitlock C (2002) Spatial variation of modern pollen in Oregon and southern Washington, USA. Review of

686

Palaeobotany and Palynology 112: 97-123. DOI: 10.1016/ S0034-6667(00)00037-3 Oldfield F, Battarbee RW, Boyle JF, et al. (2010) Terrestrial and aquatic ecosystem responses to late Holocene climate change recorded in the sediments of Lochan Uaine, Cairngorms, Scotland. Quaternary Science Reviews 29: 1040-1054. DOI: 10.1016/j.quascirev.2010.01.007 Ravazzi C (2002) Late Quaternary history of Spruce in southern Europe. Review of Palaeobotany and Palynology 120: 131-177. DOI: 10.1016/S0034-6667(01)00149-X Ren ZJ, Zhang SS (1989) Pollen and spore analysis and its implication of palaeoclimate in Tianmu Mount. Journal of Hebei Normal University (Natural Science Edition) 4: 38-41. (In Chinese) Reuss NS, Hammarlund D, Rundgren M, et al. (2010) Lake Ecosystem Responses to Holocene Climate Change at the Subarctic Tree-Line in Northern Sweden. Ecosystems 13: 393409. DOI: 10.1007/s10021-010-9326-5 Roberts DR, Hamann A (2012) Predicting potential climate change impacts with bioclimate envelope models: a palaeoecological perspective. Global Ecology and Biogeography 21: 121-133. DOI: 10.1111/j.1466-8238.2011. 00657.x Rudaya N, Tarasov P, Dorofeyuk N, et al. (2008) Holocene environments and climate in the Mongolian Altai reconstructed from the Hoton-Nur pollen and diatom records, a step towards better understanding climate dynamics in Central Asia. Quaternary Science Reviews 28: 540-554. DOI: 10.1016/j.quascirev.2008.10.013 Shen C, Liu K, Tang L, et al. (2008) Numerical Analysis of Modern and Fossil Pollen Data from the Tibetan Plateau. Annals of the Association of American Geographers 98: 755772. DOI: 10.1080/00045600802232342 Shen J, Jones RT, Yang XD, et al. (2006) The Holocene vegetation history of Lake Erhai, Yunnan province southwestern China, the role of climate and human forcings. Holocene 16: 265-276. DOI: 10.1191/0959683606hl923rp Shen J, Yang LY, Yang XD, et al. (2004) Climate change and human activities documented in lake sediments in the Erhai drainage since the Holocene. Science in China Series D: Earth Sciences 34: 130-138. (In Chinese) Song L (2012) Climatic changes documented by sediments from Genggahai Lake since the late Glacial, northeastern Tibetan Plateau. PhD Dissertation, Lanzhou University, Lanzhou, China. pp 1-150. (In Chinese) Sun AZ, Ma YZ, Feng ZD, et al. (2007) Pollen-recorded climate changes between 13.0 and 7.0 14C ka BP in southern Ningxia, China. Chinese Science Bulletin 52: 1080-1088. Sun XJ, Wang BY, Song CQ (1996) Pollen-Climate response surfaces of selected taxa from northern China. Science in China Series D: Earth Sciences 26: 431-436. (In Chinese) Sykes MT, Prentice IC, Cramer W (1996) A bioclimatic model for the potential distribution of northern European tree species under present and future climates. Journal of Biogeography 23: 203-233. The Editorial Board of Chinese Vegetation (1980) Chinese Vegetation. Science Press, Beijing, China. pp 195-197. (In Chinese) The Editorial Board of Physical Geography of China (1984) Physical Geography (Climate of China). Science Press, Beijing, China. pp 1-30. (In Chinese) The Editorial Board of Physical Geography of China (1988) Physical Geography of China (Vegetation Geography of China). Science Press, Beijing, China. pp 89-102. (In Chinese) Takhtajan A (1988) World flora zoing. Science Press, Beijing, China. pp 23-56. (In Chinese) Tao SC, An CB, Chen FH, et al. (2010) Pollen-inferred vegetation and environmental changes since 16.7 calka BP at Balikun Lake, Xinjiang. Chinese Science Bulletin 55: 24492457. Wang W, Ma YZ, Feng ZD, et al. (2009) Vegetation and climate changes during the last 8660 a BP in central Mongolia, based

J. Mt. Sci. (2013) 11 (3): 674-687

on a high-resolution pollen record from Lake Ugii Nuur. Chinese Science Bulletin 54: 1579-1589. Wang XY, Zhang GS, Zhang EL, et al. (2009) Environmental evolution research of the early-middle Holocene documented by lake sediments from Chaohu Lake. Chinese Science Bulletin 53: 153-160. Wen RL, Xiao JL, Chang ZG, et al. (2010) Holocene precipitation and temperature variations in the East Asian monsoonal margin from pollen data from Hulun Lake in northeastern Inner Mongolia, China. Boreas 39: 262-272. DOI: 10.1111/j.1502-3885.2009.00125.x Wimmer R, Grabner M (1997) Effects of climate on vertical resin duct density and radial growth of Norway spruce [Picea abies (L.)Karst.]. Trees 11: 271-276. DOI: 10.1007/PL00009 673 Wu JG (2011) The Potential Effects of Climate Change on the Distributions of Seven Arbors Plants in China. Plant Diversity and Resources 33: 335-349. (In Chinese) Wu J, Shen J (2010) Paleoclimate evolution since 27.7 ka BP reflected by grain size variation of a sediment core from Lake Xingkai, northeastern Asia. Journal of Lake Science 22: 110118. (In Chinese) Wu XH (1985) A study of palaotemperatures recorded by the Pleistocene picea-abies floras in east and southwest china. Bulletin of the Institute of Geomechaincs Cags 6: 155-166. (In Chinese) Xiao JL, Xu QH, Nakamura T, et al. (2004) Holocene vegetation variation in the Daihai Lake region of north-central China: a direct indication of the Asian monsoon climatic history. Quaternary Science Reviews 23: 1669-1679. DOI: 10.1016/j. quascirev.2004.01.005 Xiao JY, Lu HB, Zhou WJ, et al. (2007) Pollen vegetation and environmental evolution of Dahutang in Jiangxi since the Last Glacial Maximum. Science in China Series D: Earth Sciences 37: 789-797. (In Chinese) Xiao XY, Shen J, Xiao HF, et al. (2006) Pollen records and vegetation and climate changes in Heqing Basin, Yunnan Province since middle Pleistocene. Journal of Lake Science 18: 369-376. (In Chinese) Xu QH, Li YC, Yang XL, et al. (2007) Quantitative relationship between pollen and vegetation in northern China. Science in China Series D: Earth Sciences 50: 582-599. Xu QH, Li YC, Bunting MJ, et al. (2010) The effects of training set selection on the relationship between pollen assemblages and climate parameters: implications for reconstructing past climate. Palaeogeography Palaeoclimatology Palaeoecology 289: 123-133. DOI: 10.1016/j.palaeo.2010.02.024 Xu R, Kong ZC, Du NQ (1980) Picea-abice palynoflora and their signals in the Quaternary research during Peistonce in China. Quaternary Science 5: 48-56 (In Chinese)

Yang WG, Zhen HB, Xie X, et al. (2008) East Asian summer monsoon maximum records in northern south China sea during the early Holocene. Quaternary Science 28: 425-430. (In Chinese) Yuan RJ, Wang BR, Yang SH (2007) Comparative study on Picea and Abies in Hengduan mountainous areas. Journal of West China Forestry Science 36: 16-21 (In Chinese) Zhang HC, Ma YZ, Wünnemann B, et al. (2000) A Holocene climatic record from arid northwestern China. Palaeogeography Palaeoclimatology Palaeoecology 162: 389-401. DOI: 10.1016/ S0031-0182(00)00139-5 Zhao CY., Nan ZR, Cheng GD, et al. (2006) GIS-assisted modelling of the spatial distribution of Qinghai spruce (Picea crassifolia) in the Qilian Mountains, northwestern China based on biophysical parameters. Ecological Modelling 191: 487-500. DOI: 10.1016/j.ecolmodel.2005.05.018 Zhao SQ (1983) A new scheme for comprehensive physical regionalization in China. Acta Geographica Sinica 38: 1-10. (In Chinese) Zhao Y, Yu ZC, Chen FH, et al. (2007) Holocene vegetation and climate history at Hurleg Lake in the Qaidam Basin, northwest China. Review of Palaeobotany and Palynology 145: 275-288. DOI: 10.1016/j.revpalbo.2006.12.002 Zhao Y, Yu ZC, Chen FH (2009a) Spatial and temporal patterns of Holocene vegetation and climate changes in arid and semiarid China. Quaternary International 194: 6-18. DOI: 10.1016/j.quaint.2007.12.002 Zhao Y, Yu ZC, Chen FH, et al. (2009b) Vegetation response to Holocene climate change in monsoon-influenced region of China. Earth-Science Reviews 97: 242-256. DOI: 10.1016/j. earscirev.2009.10.007 Zhao Y (2010) Ecological and climatic interpretations of pollen records from lakes in the Qaidam Basin: moisture difference at different altitudes. Quaternary Science 30: 1088-1096. (In Chinese) Zhao Y, Yu ZC, Zhao WW (2011) Holocene vegetation and climate histories in the eastern Tibetan Plateau, controls by insolation-driven temperature or monsoon-derived precipitation changes?. Quaternary Science Reviews 30: 11731184. DOI: 10.1016/j.quascirev.2011.02.006 Zheng D, Freeman M, Bergh J, et al. (2002) Production of Picea abies in south-east Norway in response to climate change: a case study using process-based model simulation with field validation. Scandinavian Journal of Forest Research 17: 35-46. DOI: 10.1080/028275802317221064 Zhu Y, Chen FH, Tang LY, et al. (2001) Environmental signals of Picea and Sabina of sediments in terminal lake of Shiyang River, arid area. Journal of Desert Research 21: 141-146 (In Chinese)

687