Application and limitations of the <i>Artemisia</i>/Chenopodiaceae pollen ratio in arid and semi-arid China

Zhao, Yan; Liu, Hongyan; Li, Furong; Huang, Xiaozhong; Sun, Jinghui; Zhao, Wenwei; Herzschuh, Ulrike; Tang, Yu Lan

doi:10.1177/0959683612449762

Cited by 123 publications

(77 citation statements)

References 23 publications

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“…1a), and further data collection is still required. More recent collection of modern pollen data at regional scales, such as on the Tibetan Plateau (Lu et al, 2011;Zhang et al, 2012), arid and semi-arid northern to western China (Zhao et al, 2012), the South China Sea (Luo et al, 2013), and throughout China (Zheng et al, 2010), are not or not wholly included in our dataset. However, fossil pollen data are necessary and required for more unambiguous reconstruction of biome boundaries, especially in central eastern China between temperate and warm-temperate (subtropical) forest biomes and in central western China between temperate desert and alpine tundra biomes (Fig.…”

Section: Quality Of Pollen Data Used In This Studymentioning

confidence: 99%

Biome distribution over the last 22,000yr in China

Cao

Jeltsch

et al. 2014

Palaeogeography, Palaeoclimatology, Palaeoecology

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Patterns of past vegetation changes over time and space can help facilitate better understanding of the interactions among climate, ecosystem, and human impact. Biome changes in China over the last 22,000 yr (calibrated radiocarbon date, a BP) were numerically reconstructed by using a standard approach of pollen-plant functional type-biome assignment (biomization). The biomization procedure involves pollen data from 2434 surface sites and 228 fossil sites with a high quality of pollen count and 14 C dating, 51 natural and three anthropogenic plant functional types (PFTs), as well as 19 natural and one anthropogenic biome. Surface pollen-based reconstruction of modern natural biome patterns is in good agreement (74.4%) with actual vegetation distribution in China. However, modern large-scale anthropogenic biome reconstruction has not been successful based on the current setup of three anthropogenic PFTs (plantation, secondary, and disturbed PFT) because of the limitation of non-species level pollen identification and the difficulty in the clear assignment of disturbed PFTs. The non-anthropogenic biome distributions of 44 time slices at 500-year intervals show large-scale discrepant and changed vegetation patterns from the last glacial maximum (LGM) to the Holocene throughout China. From 22 ka BP to 19 ka BP, temperate grassland, xerophytic shrubland, and desert dominated northern China, whereas cold or cool forests flourished in central China. Warm-temperate evergreen forests were restricted to far southern China, and tropical forests were absent. During 18.5 ka BP to 12 ka BP, cold, cool, and dry biomes extended to some parts of northern, western, and eastern China. Warm-temperate evergreen and mixed forests gradually expanded to occupy the whole of southern China. A slight northward shift of forest biomes occurred from 15 ka BP to 12 ka BP. During 11.5 ka BP to 9 ka BP, temperate grassland and shrubland gradually stretched to northern and western China. Cold and cool forests widely expanded into northern and central China, as well as in the northern margin of South China along with temperate deciduous forest. Since the early mid-Holocene (approximately 8.5 ka BP to 5.5 ka BP), all forest biomes shifted northward at the expense of herbaceous and shrubby biomes. Simultaneously, cold and cool forest biomes occupied the marginal areas of the Tibetan Plateau and the high mountains in western China. During the middle to late Holocene, from 5 ka to the present, temperate grassland and xerophytic shrubland expanded to the south and east, whereas temperate deciduous forests slightly shifted southward. After 3 ka BP, forest biomes were absent in western China and on the Tibetan plateau surface. Dramatic biome shifts from the LGM to the Holocene were observed in the forest-grassland ecotone and transitional zones between temperate and subtropical climates, between subtropical and tropical regions, and in the mountainous margins of the eastern Tibetan Plateau. Evidence showed more human disturbances during the late Holocen...

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Section: Quality Of Pollen Data Used In This Studymentioning

confidence: 99%

Biome distribution over the last 22,000yr in China

Cao

Jeltsch

et al. 2014

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…Previous studies in the drylands of the Middle East (El-Moslimany 1990) have demonstrated that Chenopodiaceae are indicators of saline or non-saline desert vegetation, whereas Artemisia pollen generally increases with increasing MAP. Thus, the ratio of these two taxa has been used as an index for moisture regimes Liu et al 1999;Li et al 2005;Zhao et al , 2012. In our study, the A/C ratio was calculated to understand the response of this ratio to changes in MAP within vegetation zones in the study area and to determine if the A/C ratio can be used for semiquantitative palaeoclimate reconstructions.…”

Section: Numerical Analysismentioning

confidence: 99%

Surface pollen and its relationships with modern vegetation and climate in the Tianshan Mountains, northwestern China

Wei

Zhao

2015

Veget Hist Archaeobot

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A dataset consisting of 70 surface pollen samples from forest, alpine meadow, alpine steppe, temperate steppe, desert steppe, shrub/semi-shrub steppe and desert sites in the Tianshan Mountains, northwestern China provides an opportunity to study the relationships between surface pollen assemblages and modern vegetation and climate in this region. Redundancy analysis (RDA), the human influence index (HII) and pollen ratios were used to facilitate analysis of the pollen data. The modern pollen assemblages are primarily composed of Picea, Artemisia, Chenopodiaceae, Poaceae, Asteraceae, Nitraria and Ephedra. The results suggest that the surface pollen assemblages of different vegetation types largely represent the modern vegetation in terms of the primary taxa and dominant types. The RDA indicates that the mean annual precipitation (MAP) and the July temperature (T July ) are the major climate variables that control the modern pollen assemblages. Picea, Artemisia, Poaceae, Cyperaceae, Fabaceae, Asteraceae, Polygonaceae and Apiaceae pollen assemblages are positively correlated with MAP and negatively correlated with T July , while the pollen ratios for certain other types, such as Chenopodiaceae, Ephedra and Nitraria, are negatively correlated with MAP and positively correlated with T July . The arboreal/non-arboreal ratios are notably high in the forest samples, indicating a sensitive response to forest vegetation. Moreover, the Artemisia/Chenopodiaceae pollen ratios are generally correlated with the vegetation type and annual precipitation change, suggesting that these factors could be useful indicators of moisture variability in arid regions. However, it is difficult to distinguish between steppe and steppe desert based on this ratio, due partly to human disturbance. The HII is significantly correlated with certain pollen taxa, including Poaceae, Plantago, Polygonaceae and Elaeagnaceae, particularly in the alpine meadow and steppe samples. Our results have implications for interpreting the available fossil pollen data in the study region and other arid and semi-arid regions.

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“…Recently, Zhao et al (2012b) reviewed the reliability of the A/C ratio as humidity indicator in the arid region of China. They suggested that the A/C ratio can only be used to evaluate the humidity variations in regions with precipitation <450-500 mm, and environmental factors such as soil salinity, vegetation community composition, and human activity can also affect the validity of the A/C ratio.…”

Section: Pollen Ratios Vegetation and Climatementioning

confidence: 99%

Modern pollen assemblages from surface lake sediments in northwestern China and their importance as indicators of vegetation and climate

Feng

Zhao

et al. 2015

Sci. China Earth Sci.

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The modern pollen assemblages of surface lake sediments and topsoils in northwestern China were studied to understand the relationship of modern pollen data with contemporary vegetation and climate, and the differences between the pollen assemblages of surface lake sediments and topsoils. The results show that Chenopodiaceae and Artemisia are dominant elements in the pollen assemblages of northwestern China. Additionally, Ephedra, Cyperaceae, Asteraceae, Poaceae, Picea, Pinus, and Betula are also important pollen taxa. Both pollen assemblages and principal component analysis indicate that pollen data from surface lake sediments and topsoils can be used to differentiate the main vegetation types of this region (desert, steppe, meadow and forest). However, differences exist between modern pollen assemblages of the two types of sediments due to the different relevant source areas of pollen and degrees of pollen preservation. For example, the larger relevant source area of surface lake sediment results in a higher abundance of Betula in pollen assemblage from surface lake sediment, whereas the tendency to disintegrate thin-walled pollen types in topsoil leads to a higher proportion of resistant pollen, such as Asteraceae. Linear regression analysis indicates that the Artemisia/Chenopodiaceae (A/C) ratio in pollen assemblages of surface lake sediments can be used to indicate humidity changes in the study area. However, the A/C ratio in topsoils should be used carefully. Our results suggest that pollen data from surface lake sediments would be better references for interpreting the fossil pollen assemblages of lake cores or lacustrine profiles. Pollen data have been used to unravel the vegetation succession and climatic changes of the past since the pioneering work of von Post in 1916(Davis, 2000. The deciphering of fossil pollen data must be performed on the basis of the investigation of modern pollen assemblages. Numerous studies (e.g., Wright et al., 1967;Gaillard et al., 1992;Sugita, 1994;Cour et al., 1999;Davis, 2000;Shen et al., 2006;Ma et al., 2008;Zhao and Herzschuh, 2009;Herzschuh et al., 2010;Lu et al., 2011;Fall, 2012;Zheng et al., 2013;Tian et al., 2014) have been conducted to understand the relationship of modern pollen assemblages with contemporary vegetation and climate. Modern pollen assemblages are mainly collected from airborne pollen collectors (e.g., Cour et al

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Application and limitations of the Artemisia/Chenopodiaceae pollen ratio in arid and semi-arid China

Cited by 123 publications

References 23 publications

Biome distribution over the last 22,000yr in China

Biome distribution over the last 22,000yr in China

Surface pollen and its relationships with modern vegetation and climate in the Tianshan Mountains, northwestern China

Modern pollen assemblages from surface lake sediments in northwestern China and their importance as indicators of vegetation and climate

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