Modern pollen assemblages of the surface lake sediments from the steppe and desert zones of the Tibetan Plateau

Feng, Qiming

doi:10.1007/s11430-020-9693-y

Cited by 18 publications

(7 citation statements)

References 52 publications

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“…Ulmus is a drought-tolerant and light-demanding plant which can survive at precipitation levels lower than 200 mm yr −1 (Shen et al, 2005). Previous modern pollen studies reveal that Amaranthaceae and Ephedra are commonly found in the desert, indicating a tolerance for dry climatic conditions (Yu et al, 2001;Huang et al, 2018;Qin, 2021) and our modern pollen dataset for the east Tibetan Plateau suggests that xerophilous taxa, such as Ephedra and Amaranthaceae, are restricted to areas with P ann lower than 400 mm, and almost absent in samples with high precipitation (Fig. 2).…”

Section: Determination Of Exogenous Pollen Grainssupporting

confidence: 65%

Palynological evidence reveals an arid early Holocene for the northeast Tibetan Plateau

et al. 2022

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Abstract. Situated within the triangle of the East Asian monsoon, the Indian monsoon, and the westerlies, the Holocene patterns of climate and vegetation changes on the northeast Tibetan Plateau are still unclear or even contradictory. By investigating the distribution of modern pollen taxa on the east Tibetan Plateau, we infer the past vegetation and climate since 14.2 ka BP (1000 years before present) from a fossil pollen record extracted from Gahai Lake (102.3133∘ E, 34.2398∘ N; 3444 m a.s.l.) together with multiple proxies (grain size, contents of total organic carbon and total nitrogen) on the northeast Tibetan Plateau. Results indicate that the Gahai Basin was covered by arid alpine steppe or even desert between 14.2 and 7.4 ka BP with dry climatic conditions, and high percentages of arboreal pollen are thought to be long-distance wind- transported grains. Montane forest (dominated by Abies, Picea, and Pinus) migrated into the Gahai Basin between 7.4 and 3.8 ka BP driven by wet and warm climatic conditions (the climate optimum within the Holocene) but reverted to alpine steppe between 3.8 and 2.3 ka BP, indicating a drying climate trend. After 2.3 ka BP, vegetation shifted to alpine meadow represented by increasing abundances of Cyperaceae, which may reflect a cooling climate. The strange pollen spectra with high abundances of Cyperaceae and high total pollen concentrations after ca. 0.24 ka BP (1710 CE) could be an indication of disturbance by human activities to some extent, but needs more direct evidence to be confirmed. Our study confirms the occurrence of a climate optimum in the mid-Holocene on the northeast Tibetan Plateau, which is consistent with climate records from the fringe areas of the East Asian summer monsoon, and provides new insights into the fluctuations in the intensity and extent of the Asian monsoon system.

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Section: Determination Of Exogenous Pollen Grainssupporting

confidence: 65%

Palynological evidence reveals an arid early Holocene for the northeast Tibetan Plateau

et al. 2022

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“…The alpine steppe has a high proportion of Cyperaceae, which is unlike typical alpine steppe, and the samples are clustered in the eastern part of the south‐eastern Tibetan Plateau. Herzschuh (2007) and Qin (2021) suggest that higher amounts of Cyperaceae pollen are expected in this eastern area because of its higher precipitation. The main pollen taxa of alpine steppe‐shrub in our data set are Artemisia , Cyperaceae and Asteraceae, but arboreal and shrub taxa only appeared sporadically in individual samples, in contrast to assemblages from typical alpine shrublands.…”

Section: Discussionmentioning

confidence: 99%

“…This model has been used to evaluate the accuracy of the relationship between pollen assemblages and vegetation type (Sobol & Finkelstein 2018; Sobol et al . 2019; Qin 2021). Here, we evaluate which pollen taxa should be included by selecting random samples several times and assessing the output results, and then optimize the model by deleting the least important variables.…”

Section: Methodsmentioning

confidence: 99%

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A modern pollen data set for the forest–meadow–steppe ecotone from the Tibetan Plateau and its potential use in past vegetation reconstruction

Wang

Liu

Zhang

et al. 2022

Boreas

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The relationship between modern pollen andvegetation provides the basis for the interpretation of stratigraphic pollen assemblages and the quantitative reconstruction of past vegetation. We selected 168 topsoil samples from four different vegetation types on the south-eastern Tibetan Plateau to explore the relationships between pollen assemblages, vegetation and climate. The results reveal that pollen assemblages discriminate the vegetation types well; the subalpine coniferous and evergreen broad-leaved forest is characterized by a high proportion of arboreal taxa (e.g. Pinus, Picea, Betula); the alpine shrub and meadow and alpine steppe vegetation types are dominated by Cyperaceae, followed by Artemisia and Brassicaceae; and the alpine steppe-shrub is characterized by a high percentage of Artemisia, with Cyperaceae, Asteraceae and Brassicaceae as common taxa. Redundancy analysis shows that mean temperature of the coldest month (Mt co ) is the main climatic factor that influences pollen distribution. Pollen diversity indices (including richness and evenness) gradually decrease from SE to NW. The random forest classification has good performance in distinguishing vegetation types. Our study supplies a comparatively detailed description of the relationship between the pollen assemblage and vegetation in the forest-meadow-steppe ecotone on the south-eastern Tibetan Plateau. In addition, the random forest model has potential application for reconstructing the past vegetation type of the fossil pollen spectra on the south-eastern Tibetan Plateau.

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“…In recent years, studies on the reconstruction of paleovegetation, paleoclimate, and paleomonsoon in Southwest China based on fossil pollen have been increasing gradually ( Xiao et al, 2014 ; Zhang et al, 2020 ). Nevertheless, studies on topsoil pollen in China are mainly concentrated in northern China ( Xu Q. H. et al, 2005 , Lu et al, 2006 ; Xu et al, 2007 ; Li et al, 2008 , 2012 ; Luo et al, 2010 ) and the Tibetan Plateau ( Lu et al, 2004 ; Wei et al, 2018 ; Zhang et al, 2018 ; Qin, 2021 ), yet these studies conducted in southern China are relatively weak. Previous studies mainly rely on subjective empirical inference when interpreting the environmental significance of sedimentary pollen and phytoliths, failing to give accurate quantitative results.…”

Section: Introductionmentioning

confidence: 99%

Surface phytolith and pollen assemblages of a low-latitude subtropical region in Southwest China and their implications for vegetation and climate

Wang

Yang²,

Yang³

et al. 2022

Front. Plant Sci.

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Phytoliths, as a newly developing plant proxy, have broad application prospects in paleoclimate and paleoethnobotany. However, the shortage of studies regarding tropical-subtropical plants and topsoil phytoliths interferes with the research progress on primitive humanity’s utilization of plant resources and paleoclimate in the region. This research focuses on the subtropical mountainous region with a monsoon climate of low latitudes in Southwest China to conduct phytolith morphology analysis of living plants and phytolith/pollen assemblages of topsoil to reveal the indicative significance of vegetation and climate. A total of 111 species from 50 families, including 73 species from 33 tree/shrub families, 31 species from 12 herb families and 7 species from 5 fern families, were collected for morphological characteristics analysis, as well as 19 topsoil specimens for phytolith and pollen assemblage analysis. The results suggest that phytoliths are mainly deposited in situ, with assemblages of topsoil corresponding well with plant types in the quadrat and being able to exhibit constructive species in small regions. In comparison, pollen assemblages of topsoil dominantly respond to regional vegetation due to their long-distance transportation and widespread presence, in addition to their characteristics that correspond to the vegetation in the quadrat. The topsoil phytolith assemblages are mainly based on the elongate-bulliform flabellate-square/rectangle-broadleaf-types (including spheroid echinate), and the vegetation types indicate the subtropical climate. In addition, phytolith assemblages of Poaceae are dominated by collapsed saddle-bulliform flabellate square/rectangle-elongate-point, reflecting warm and humid conditions. The pollen assemblages mainly consist of Pinus, Betula, Alnus, deciduous Quercus, Euphorbiaceae, Rhamnaceae and Polygonum, reflecting tropical-subtropical plant communities and indicating warm and humid conditions. Overall, phytolith and pollen assemblages have unique characteristics and are thus explicitly representative of the low-latitude subtropical monsoon climate.

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Modern pollen assemblages of the surface lake sediments from the steppe and desert zones of the Tibetan Plateau

Cited by 18 publications

References 52 publications

Palynological evidence reveals an arid early Holocene for the northeast Tibetan Plateau

Palynological evidence reveals an arid early Holocene for the northeast Tibetan Plateau

A modern pollen data set for the forest–meadow–steppe ecotone from the Tibetan Plateau and its potential use in past vegetation reconstruction

Surface phytolith and pollen assemblages of a low-latitude subtropical region in Southwest China and their implications for vegetation and climate

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