Indicator pollen taxa of human-induced and natural vegetation in Northern China

Li, Manyue; Xu, Qinghai; Zhang, Shengrui; Li, Yuecong; Ding, Wenfeng; Li, Jianyong

doi:10.1177/0959683614566219

Cited by 39 publications

(18 citation statements)

References 61 publications

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“…Larix is the dominant taxon in the GHM (Yu et al, 2011). However, Larix produces little pollen (Li et al, 2015) with poor preservation of intact grains making identification difficult. Low percentages of Larix pollen were detected in all records (0.7–11.2% XJL; 0.3% GAL; 0.3–2% JNTC; 0.3–3% AN; 0.3–2% CHL) and trends broadly followed the conifer Pinus in sites with ˃2% pollen (see Supplementary Figures S2‐6).…”

Section: Resultsmentioning

confidence: 99%

Environmental change and human land‐use over the past 200 years in the Great Hinggan Mountains, Northeastern China

et al. 2020

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Mountain ecosystems are sensitive to environmental changes and are affected by direct and indirect anthropogenic activities. This study sought to understand the impacts of human occupation, environmental and climate change on the Great Hinggan Mountains (GHM) in Northeastern China. The last 200 years of environmental changes are reconstructed by analyzing sediment cores from five small mountain lakes. Cores were dated using 210Pb and 137Cs radioisotopes, microscopic charcoal identified regional fire activity and fossil pollen analysis reconstructed temporal and spatial changes in vegetation. Peaks in 137Cs, 226Ra and microscopic charcoal flux were found to follow similar trends between sites. The radioisotope records reflect redistribution processes, such as erosion and fire events, which overwhelm the atmospheric fallout signal in the GHM. Microscopic charcoal increased from 1950 CE and peaked at all sites after 2000 CE suggesting that current fire management, coupled with a warmer climate due to global warming, may be leading to more wildfire events in the region. Pinus, Quercus and Betula declined at all sites as human occupation occurred in the early 1900s. Initially, open forest and grassland expanded in response to overexploitation of forests, followed by arboreal pollen reaching maximum values after 2000 CE. This study concludes that the present‐day mixed coniferous broad‐leaved forest dominating the southern region of the GHM is a product of changing fire activity, excessive logging and, more recently, forestry management and vegetation regeneration. Results suggest further management strategies are needed to address land degradation and wildfire events in mountain regions of Northeastern China.

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Section: Resultsmentioning

confidence: 99%

Environmental change and human land‐use over the past 200 years in the Great Hinggan Mountains, Northeastern China

et al. 2020

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“…It should be clearly noted that pollen from cereal-type Poaceae and other distinct cultivated taxa (e.g. Brassica, Gossypium, Sesamum, and Linum) identified in the H-set Li et al, 2015) were excluded to reduce anthropogenic noise. This strategy is similar to the one excluding aquatic pollen and spores in order to better catch the climatic signal.…”

Section: Surface Pollen Datamentioning

confidence: 99%

“…terraced fields) in the humid and subhumid regions, tree pollen percentages decrease and herb percentages increase substantially in surface samples, even after excluding distinctly cultivated taxa. It is easy to imagine that herbaceous taxa, such as Artemisia, Chenopodiaceae, Humulus, and weed-type Poaceae would expand after forest clearance and this will change the regional vegetation composition and relative pollen abundances Li et al, 2015). It will also alter the pollen-climate relationships for many pollen taxa in the response models (St. Jacques et al, 2008).…”

Section: Climatic Signals In Pollen Assemblages Obscured By Human Impactmentioning

confidence: 99%

Examining bias in pollen-based quantitative climate reconstructions induced by human impact on vegetation in China

Ding

Tarasov

2017

Clim. Past

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Abstract. Human impact is a well-known confounder in pollen-based quantitative climate reconstructions as most terrestrial ecosystems have been artificially affected to varying degrees. In this paper, we use a "human-induced" pollen dataset (H-set) and a corresponding "natural" pollen dataset (N-set) to establish pollen-climate calibration sets for temperate eastern China (TEC). The two calibration sets, taking a weighted averaging partial least squares (WA-PLS) approach, are used to reconstruct past climate variables from a fossil record, which is located at the margin of the East Asian summer monsoon in north-central China and covers the late glacial Holocene from 14.7 ka BP (thousands of years before AD 1950). Ordination results suggest that mean annual precipitation (P ann ) is the main explanatory variable of both pollen composition and percentage distributions in both datasets. The P ann reconstructions, based on the two calibration sets, demonstrate consistently similar patterns and general trends, suggesting a relatively strong climate impact on the regional vegetation and pollen spectra. However, our results also indicate that the human impact may obscure climate signals derived from fossil pollen assemblages. In a test with modern climate and pollen data, the P ann influence on pollen distribution decreases in the H-set, while the human influence index (HII) rises. Moreover, the relatively strong human impact reduces woody pollen taxa abundances, particularly in the subhumid forested areas. Consequently, this shifts their model-inferred P ann optima to the arid end of the gradient compared to P ann tolerances in the natural dataset and further produces distinct deviations when the total tree pollen percentages are high (i.e. about 40 % for the Gonghai area) in the fossil sequence. In summary, the calibration set with human impact used in our experiment can produce a reliable general pattern of past climate, but the human impact on vegetation affects the pollen-climate relationship and biases the pollen-based climate reconstruction. The extent of human-induced bias may be rather small for the entire late glacial and early Holocene interval when we use a reference set called natural. Nevertheless, this potential bias should be kept in mind when conducting quantitative reconstructions, especially for the recent 2 or 3 millennia.

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“…Human influence has been evaluated as a potential source of bias in pollen‐based quantitative climate reconstructions in China (Li et al ., ; Ding et al ., ). In addition, numerous studies on pollen content in farmland and wasteland topsoil in different regions of central and eastern China have provided valuable information on pollen types and assemblage characteristics in relation to the influence of human activities (Yang et al ., ; Ding et al ., ; Pang et al ., ; Li et al ., ). In the QTP, studies on modern pollen assemblages and related vegetation have been widely carried out to help interpret fossil pollen spectra (Shang et al ., ; Zhao and Herzschuh, ; Herzschuh et al ., ; Lu et al ., ; Wei et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Assessing the impact of human activities on surface pollen assemblages in Qinghai Lake Basin, China

Wei

Qin

et al. 2018

J Quaternary Science

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The aim of this study is to evaluate the local impact of human activities on surface pollen assemblages and identify pollen indicators associated with grazing and cultivation in the Qinghai-Tibetan Plateau. We analyzed 80 surface and 10 dung pollen samples from five communities of vegetation in the Qinghai Lake Basin. Each vegetation zone was identifiable based on surface pollen assemblages. Principal component analysis of 33 pollen taxa and two supplementary variables of human influences was used to assess the impact of anthropogenic activities on surface pollen assemblages in the Qinghai Lake Basin. Surface pollen assemblages were moderately influenced by cultivation, as indicated by the content of the cultivation-associated Hordeum-type and Brassiaceae pollen. Severe grazing led to changes in pollen assemblages, including increases in Chenopodiaceae, Plantago, Potentilla-type, Thymelaeaceae and Aster-type pollen. Pollen assemblages are similar among dung samples and are dominated by Artemisia, Poaceae, Fabaceae and Asteraceae. Hordeum-type pollen content is relatively higher in dung samples, indicating herbivores are important in the dispersion of Cerealia Poaceae pollen into pastures. Characterizing modern pollen assemblages will provide a more precise reference for reconstructing prehistoric human activities during the Holocene based on fossil pollen assemblages in the Qinghai Lake Basin.

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Indicator pollen taxa of human-induced and natural vegetation in Northern China

Cited by 39 publications

References 61 publications

Environmental change and human land‐use over the past 200 years in the Great Hinggan Mountains, Northeastern China

Environmental change and human land‐use over the past 200 years in the Great Hinggan Mountains, Northeastern China

Examining bias in pollen-based quantitative climate reconstructions induced by human impact on vegetation in China

Assessing the impact of human activities on surface pollen assemblages in Qinghai Lake Basin, China

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