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Arid Land Geography ›› 2023, Vol. 46 ›› Issue (5): 773-781.doi: 10.12118/j.issn.1000-6060.2022.437

• Biology and Pedology • Previous Articles     Next Articles

Indicative study of pollen on vegetation in western Junger Basin

HAN Yueting(),LI Jianyong(),LIU Jianbo,YANG Rui,NIU Diyuan   

  1. College of Urban and Environmental Sciences, Northwest University, Xi’an 710127, Shaanxi, China
  • Received:2022-09-04 Revised:2022-11-16 Online:2023-05-25 Published:2023-06-05

Abstract:

Pollen records have been widely employed as a significant proxy to reconstruct paleovegetation distribution as well as its spatiotemporal evolution worldwide. Due to the marked influence of many factors, such as differences among pollen productivity, transportation mode, biological characteristics of plants, climatic condition, and sedimentary environment, the associated relationship between pollen and vegetation has been shown to be fairly complicated in different regions. As a result, the information regarding the plant community reflected by the pollen assemblage is significantly different from that of the real situation. Therefore, it is clearly necessary to conduct a large number of studies to deeply explore the quantitative relationship between pollen assemblages and vegetation community. Based on vegetation survey and surface pollen data collected from 46 surface soil samples in the western Junggar Basin of Xinjiang, China, this study used various approaches to quantitatively estimate several pollen-based indices representative of vegetation, including the association index (A), underrepresentation index (U), overrepresentation index (O), representative coefficient (R), mean pollen percentage in the absence of vegetation (Ma), mean pollen percentage in the presence of vegetation (Mp), and coefficient of similarity between pollen assemblage and plant community (CC) for 19 major pollen types in our study region. The results of the analysis show that all the 19 pollen taxa can be divided into three groups. The first group includes Chenopodiaceae with A value of 1.0, O and U values of 0, and R value of 12.5. The value of Mp is much higher than Ma, therefore indicating that Chenopodiaceae pollen is over-representative for the corresponding vegetation. The second group consists of Artemisia and Ephedra, in which A values range from 0.1 to 0.4, O values vary from 0.6 to 0.9, U values are 0, and R values are greater than 18.5. Moreover, the differences in values between Mp and Ma range from 3.6% to 12.1%, implying a strong association between pollen distribution and their parent plants. The third group includes various pollen types of Nitraria, Liliaceae, Labiatae, Fabaceae, Poaceae, Asteraceae, Polygonaceae, Ranunculaceae, Rosaceae, Umbelliferae, Brassicaceae, Caryophyllaceae, Convolvulaceae, Urticaceae, and Boraginaceae, with A values of less than 0.6, U values between 0.2 and 0.9, O values between 0.1 and 1.0, and R values of less than 4.0. Moreover, the differences in values between Mp and Ma less than 4.9%, therefore showing that these pollen types are under-representative for the related vegetation. These results provide a basis to improve the reliability of pollen-based vegetation reconstruction.

Key words: pollen, vegetation, representative index, coefficient of similarity, Junggar Basin