Modern Pollen Rain in the Tibetan Plateau

The basis for the interpretation of fossil-pollen assemblages in terms of vegetation and climate is the present-day relationship of vegetation and climate to pollen rain. Detailed modern pollen spectra from the Tibetan Plateau are described here to explore the relationship between modern pollen rain and vegetation. Two hundred and thirty four (234) pollen surface samples were collected from moss polsters, top soil, and lake surface sediments from forests, shrublands, shrub meadows, meadows, steppes, and deserts in the Tibetan Plateau. Pollen assemblages from each vegetation type are detailed described using pollen percentage data, and compared descriptively and numerically using cluster analysis. Pollen spectra from forests are characterized by high percentages of tree pollen types including Pinus, Abies, Picea, Quercus, and Betula. Pollen spectra from shrublands have highest amounts of shrub pollen. The dominants of shrublands, such as Rhododendron, Juniperus, Salix, and shrub Quercus, are well-represented in most of these pollen spectra. Pollen spectra from shrub meadows have less shrub pollen than those from shrublands, but more than those from meadows, steppes and deserts. The most frequent shrub pollen in this vegetation type is Rosaceae. Most of pollen spectra from shrub meadows are dominated by Cyperaceae pollen. Pollen spectra from meadows are characterized by the very high percentages of Cyperaceae pollen. The highest amounts of Cyperaceae pollen occur in pollen spectra from alpine-marshy meadows. Pollen spectra from Stipa steppes are characterized by the highest percentages of Poaceae pollen, and high Cyperaceae pollen percentages, whereas pollen spectra from Artemisia steppes have the highest percentages of Artemisia pollen. Pollen spectra from arid deserts are dominated by Chenopodiaceae. Main vegetation types can be distinguished by their modern pollen rain, i.e., modern pollen spectra do reflect the modern vegetation at local and regional scale in the Tibetan Plateau. This modern pollen database can thus be used to explore the pollen/vegetation and pollen/climate relationships by a variety of numerical methods.

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Modern Pollen Assemblages in Typical Agro-Pastoral Ecotone in the Eastern Tibetan Plateau and Its Implications for Anthropogenic Activities

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.685942 ◽

2021 ◽

Vol 9 ◽

Author(s):

Ronglei Duan ◽

Haicheng Wei ◽

Guangliang Hou ◽

Jingyi Gao ◽

Yongsheng Du ◽

...

Keyword(s):

Tibetan Plateau ◽

Anthropogenic Activities ◽

Principal Component ◽

Environment Interaction ◽

Human Environment ◽

Surface Pollen ◽

Modern Pollen ◽

Pollen Types ◽

Poaceae Pollen ◽

The Impact

Long-term evolution of human-environment interaction in the Qinghai-Tibetan Plateau (QTP) has been discussed intensively in recent years. The identification of human-related pollen types may help explore the coupled process of climate change, ecological response and anthropogenic activities on the QTP. The aim of this study is to evaluate the impact of anthropogenic activities on surface pollen assemblages and identify pollen indicators associated with grazing and cultivation in typical agro-pastoral ecotone of the eastern QTP. Totally 84 surface samples were analyzed from five vegetational communities in the eastern QTP, which are identifiable based on surface pollen assemblages. Principal component analysis of 29 pollen types and two supplementary variables of human influences were used to assess the impact of anthropogenic activities on surface pollen assemblages in eastern QTP. Severe grazing led to increase of Rosaceae, Ranunculaceae, Fabaceae, Taraxacum-Type, Aster-type and Saussurea-Type in pollen assemblages. Highland agricultural cultivation can be identified by the content and morphological characteristic of Brassicaceae and Cerealia Poaceae pollen. The aerial dispersed distances of Brassicaceae and Cerealia Poaceae pollen are very short, and domesticated herbivores are important factors, which disperse the Cerealia Poaceae pollen into pastures in agro-pastoral ecotone of the QTP. Modern pollen indicators of cultivation and grazing activity will provide precise references for fossil pollen study of prehistoric human activities in the QTP.

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Lake surface-sediment pollen dataset for the alpine meadow vegetation type from the eastern Tibetan Plateau and its potential in past climate reconstructions

10.5194/essd-2021-90 ◽

2021 ◽

Author(s):

Xianyong Cao ◽

Fang Tian ◽

Kai Li ◽

Jian Ni ◽

Xiaoshan Yu ◽

...

Keyword(s):

Tibetan Plateau ◽

Surface Sediment ◽

Alpine Meadow ◽

Vegetation Type ◽

Weighted Averaging ◽

Climatic Data ◽

The Tibetan Plateau ◽

Eastern Tibetan Plateau ◽

Lake Surface ◽

Modern Pollen

Abstract. A modern pollen dataset with an even distribution of sites is essential for pollen-based past vegetation and climate estimations. As there were geographical gaps in previous datasets covering the central and eastern Tibetan Plateau, lake surface-sediment samples (n=117) were collected from the alpine meadow region on the Tibetan Plateau between elevations of 3720 and 5170 m a.s.l. Pollen identification and counting were based on standard approaches, and modern climate data were interpolated from a robust modern meteorological dataset. A series of numerical analyses revealed that precipitation is the main climatic determinant of pollen spatial distribution; Cyperaceae, Ranunculaceae, Rosaceae, and Salix indicate wet climatic conditions, while Poaceae, Artemisia, and Chenopodiaceae represent drought. Model performance of both weighted-averaging partial least squares (WA-PLS) and the random forest (RF) algorithm suggest that this modern pollen dataset has good predictive power in estimating the past precipitation for pollen spectra from the eastern Tibetan Plateau. In addition, a comprehensive modern pollen dataset can be established by combining our modern pollen dataset with previous datasets, which will be essential for the reconstruction of vegetation and climatic signals for fossil pollen sprecta on the Tibetan Plateau. Pollen datasets including both pollen counts and percentages for each sample together with their site location and climatic data are available at the National Tibetan Plateau Data Center (TPDC; DOI: 10.11888/Paleoenv.tpdc.271191).

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Lake surface sediment pollen dataset for the alpine meadow vegetation type from the eastern Tibetan Plateau and its potential in past climate reconstructions

Earth System Science Data ◽

10.5194/essd-13-3525-2021 ◽

2021 ◽

Vol 13 (7) ◽

pp. 3525-3537

Author(s):

Xianyong Cao ◽

Fang Tian ◽

Kai Li ◽

Jian Ni ◽

Xiaoshan Yu ◽

...

Keyword(s):

Tibetan Plateau ◽

Surface Sediment ◽

Alpine Meadow ◽

Vegetation Type ◽

Weighted Averaging ◽

Climatic Data ◽

The Tibetan Plateau ◽

Eastern Tibetan Plateau ◽

Lake Surface ◽

Modern Pollen

Abstract. A modern pollen dataset with an even distribution of sites is essential for pollen-based past vegetation and climate estimations. As there were geographical gaps in previous datasets covering the central and eastern Tibetan Plateau, lake surface sediment samples (n=117) were collected from the alpine meadow region on the Tibetan Plateau between elevations of 3720 and 5170 m a.s.l. Pollen identification and counting were based on standard approaches, and modern climate data were interpolated from a robust modern meteorological dataset. A series of numerical analyses revealed that precipitation is the main climatic determinant of pollen spatial distribution: Cyperaceae, Ranunculaceae, Rosaceae, and Salix indicate wet climatic conditions, while Poaceae, Artemisia, and Chenopodiaceae represent drought. Model performance of both weighted-averaging partial least squares (WA-PLS) and the random forest (RF) algorithm suggest that this modern pollen dataset has good predictive power in estimating the past precipitation from pollen spectra from the eastern Tibetan Plateau. In addition, a comprehensive modern pollen dataset can be established by combining our modern pollen dataset with previous datasets, which will be essential for the reconstruction of vegetation and climatic signals for fossil pollen spectra on the Tibetan Plateau. Pollen datasets including both pollen counts and percentages for each sample, together with their site location and climatic data, are available at the National Tibetan Plateau Data Center (TPDC; Cao et al., 2021; https://doi.org/10.11888/Paleoenv.tpdc.271191).

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Quantitative relationships between modern pollen rain and climate in the Tibetan Plateau

Review of Palaeobotany and Palynology ◽

10.1016/j.revpalbo.2006.03.001 ◽

2006 ◽

Vol 140 (1-2) ◽

pp. 61-77 ◽

Cited By ~ 127

Author(s):

Caiming Shen ◽

Kam-biu Liu ◽

Lingyu Tang ◽

Jonathan T. Overpeck

Keyword(s):

Tibetan Plateau ◽

The Tibetan Plateau ◽

Modern Pollen ◽

Pollen Rain

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Spatial-Temporal Patterns and Controls of Evapotranspiration across the Tibetan Plateau (2000–2012)

Advances in Meteorology ◽

10.1155/2017/7082606 ◽

2017 ◽

Vol 2017 ◽

pp. 1-12 ◽

Cited By ~ 12

Author(s):

Hao Zhang ◽

Jian Sun ◽

Junnan Xiong

Keyword(s):

Tibetan Plateau ◽

Environmental Factors ◽

Vegetation Type ◽

Middle Part ◽

Rate Of Change ◽

Ecological Indicator ◽

The Tibetan Plateau ◽

Grassland Ecosystems ◽

Key Factor ◽

Positive Correlations

Evapotranspiration (ET) is a key factor to further our understanding of climate change processes, especially on the Tibetan Plateau, which is sensitive to global change. Herein, the spatial patterns of ET are examined, and the effects of environmental factors on ET at different scales are explored from the years 2000 to 2012. The results indicated that a steady trend in ET was detected over the past decade. Meanwhile, the spatial distribution shows an increase of ET from the northwest to the southeast, and the rate of change in ET is lower in the middle part of the Tibetan Plateau. Besides, the positive effect of radiation on ET existed mainly in the southwest. Based on the environment gradient transects, the ET had positive correlations with temperature (R>0.85, p<0.0001), precipitation (R > 0.89, p < 0.0001), and NDVI (R > 0.75, p < 0.0001), but a negative correlation between ET and radiation (R = 0.76, p < 0.0001) was observed. We also found that the relationships between environmental factors and ET differed in the different grassland ecosystems, which indicated that vegetation type is one factor that can affect ET. Generally, the results indicate that ET can serve as a valuable ecological indicator.

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Pollen Taphonomy in a Canyon Stream

Quaternary Research ◽

10.1016/0033-5894(87)90006-8 ◽

1987 ◽

Vol 28 (3) ◽

pp. 393-406 ◽

Cited By ~ 51

Author(s):

Patricia L. Fall

Keyword(s):

Surface Soil ◽

Pollen Grains ◽

Close Correlation ◽

Soil Samples ◽

Alluvial Deposits ◽

Modern Pollen ◽

Pollen Types ◽

Pollen Rain ◽

Arid Steppe ◽

Turbulent Water

AbstractSurface soil samples from the forested Chuska Mountains to the arid steppe of the Chinle Valley, Northeastern Arizona, show close correlation between modern pollen rain and vegetation. In contrast, modern alluvium is dominated by Pinus pollen throughout the canyon; it reflects neither the surrounding floodplain nor plateau vegetation. Pollen in surface soils is deposited by wind; pollen grains in alluvium are deposited by a stream as sedimentary particles. Clay-size particles correlate significantly with Pinus, Quercus, and Populus pollen. These pollen types settle, as clay does, in slack water. Chenopodiaceae-Amaranthus, Artemisia, other Tubuliflorae, and indeterminate pollen types correlate with sand-size particles, and are deposited by more turbulent water. Fluctuating pollen frequencies in alluvial deposits are related to sedimentology and do not reflect the local or regional vegetation where the sediments were deposited. Alluvial pollen is unreliable for reconstruction of paleoenvironments.

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Modern pollen assemblages and their relationships to vegetation and climate in the Lhasa Valley, Tibetan Plateau, China

Quaternary International ◽

10.1016/j.quaint.2018.01.040 ◽

2018 ◽

Vol 467 ◽

pp. 210-221 ◽

Cited By ~ 4

Author(s):

Yan-Jie Zhang ◽

La Duo ◽

You-Zhi Pang ◽

Vivian A. Felde ◽

Hilary H. Birks ◽

...

Keyword(s):

Tibetan Plateau ◽

Modern Pollen ◽

Vegetation And Climate ◽

Modern Pollen Assemblages

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Modern pollen rain, vegetation and climate along elevation gradients in the upper-middle Yellow River: numerical approaches for quantitative environmental reconstruction

Grana ◽

10.1080/00173134.2019.1677769 ◽

2019 ◽

Vol 59 (4) ◽

pp. 258-272

Author(s):

Hua Zhang ◽

Qiuchi Wan ◽

Zhuo Zheng ◽

Haicheng Wei ◽

Kangyou Huang

Keyword(s):

Yellow River ◽

Environmental Reconstruction ◽

Elevation Gradients ◽

Modern Pollen ◽

Pollen Rain ◽

Vegetation And Climate ◽

Numerical Approaches

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Quantitative climate and vegetation trends since the late glacial on the northeastern Tibetan Plateau deduced from Koucha Lake pollen spectra

Quaternary Research ◽

10.1016/j.yqres.2008.09.003 ◽

2009 ◽

Vol 71 (2) ◽

pp. 162-171 ◽

Cited By ~ 112

Author(s):

Ulrike Herzschuh ◽

Annette Kramer ◽

Steffen Mischke ◽

Chengjun Zhang

Keyword(s):

Tibetan Plateau ◽

Vegetation Change ◽

Late Glacial ◽

Quantitative Information ◽

The Tibetan Plateau ◽

Climate History ◽

Climate Conditions ◽

Northeastern Tibetan Plateau ◽

Vegetation And Climate ◽

Cool Climate

AbstractQuantitative information on vegetation and climate history from the late glacial–Holocene on the Tibetan Plateau is extremely rare. Here, we present palynological results of a 4.30-m-long sediment record collected from Koucha Lake in the Bayan Har Mountains, northeastern Tibetan Plateau. Vegetation change has been traced by biomisation, ordination of pollen data, and calculation of pollen ratios. The application of a pollen–climate calibration set from the eastern Tibetan Plateau to Koucha Lake pollen spectra yielded quantitative climate information. The area was covered by alpine desert/steppe, characteristic of a cold and dry climate (with 50% less precipitation than today) between 16,700 and 14,600 cal yr BP. Steppe vegetation, warm (∼ 1°C higher than today) and wet conditions prevailed between 14,600 and 6600 cal yr BP. These findings contradict evidence from other monsoon-influenced areas of Asia, where the early Holocene is thought to have been moist. Low effective moisture on the northeastern Tibetan Plateau was likely due to high temperature and evaporation, even though precipitation levels may have been similar to present-day values. The vegetation changed to tundra around 6600 cal yr BP, indicating that wet and cool climate conditions occurred on the northeastern Tibetan Plateau during the second half of the Holocene.

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