Pollen assemblage characteristics of lakes in the monsoon fringe area of China |
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Authors: | Fang Tian QingHai Xu YueCong Li XianYong Cao XueLi Wang LiYan Zhang |
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Institution: | (1) College of Resources and Environmental Sciences, Hebei Normal University, Shijiazhuang, 050016, China;(2) Hebei Key Laboratory of Environmental Change and Ecological Construction, Shijiazhuang, 050016, China;(3) Key Laboratory of Western China’s Environmental System (Ministry of Education), Lanzhou University, Lanzhou, 730000, China |
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Abstract: | This paper presents the pollen assemblages from 108 surface sediment samples from 4 lakes (the Lake Daihai, Lake Hongjiannao,
Lake Hulunnao and Lake Duikounao) in the monsoon fringe area of China. The herb pollen taxa Artemisia, Chenopodiaceae, Poaceae and Compositae are the major components of pollen assemblages of the 4 lakes and Pinus, Betula, Quercus, Ulmus, Populus, Ostryopsis and Elaeagnaceae are frequently presented, which reflect regional and local vegetation well. The mean similarity coefficients
for samples from the Lake Daihai, Lake Hongjiannao, Lake Hulunnao and Lake Duikounao are 0.66 ± 0.17, 0.71 ± 0.11, 0.73 ±
0.12 and 0.67 ± 0.12 respectively, so pollen assemblages are relatively consistent in each lake, which shows that focusing
and mixing effects have occurred before and after pollen deposition. However, pollen assemblages do differ between sampling
sites in each lake. The largest difference is seen in the Lake Daihai, followed by the Lake Duikounao, Lake Hulunnao and Lake
Hongjiannao (The mean Euclidean distance is 20.09 ± 11.11, 11.22 ± 3.64, 10.67 ± 4.03 and 8.44 ± 4.51 respectively). These
differences are possibly caused by the differences of focusing and mixing effects, pollen source areas, drainage areas and
regional vegetation compositions. The Lake Daihai and Lake Hongjiannao have water deeper than 5 m and strong re-suspension,
focusing and mixing effects occur in the lakeshore and shallow water areas, where pollen concentrations are lower than in
deeper lake areas. In the Lake Hulunnao and Lake Duikounao, with depths less than 5 m, re-suspension and mixing effects are
obvious across the whole lake area, so pollen assemblages and pollen concentrations are more consistent among sampling sites
in each lake. Comparison between the lake samples and samples from the inflowing river reveals that wind is primary pollen
transportation force in the Lake Hongjiannao, where the consistency of pollen assemblage is conspicuous, while there is greater
variation in lakes where pollen input is dominated by waterborne sources.
Supported by the Preliminary Special Foundation for National Basic Research Program of China (Grant No. 2003CCA01800), the
Major Program of National Natural Science Foundation of China (Grant No. 40730103), National Natural Science Foundation of
China (Grant Nos. 40571166 and 40672107), the Master Foundation Ministry of Education (Grant No.20050094004), Hebei Special
Foundation for Ph.D (Grant No. 06547006-3) and Hebei Foundation for the Key Subject Construction of University |
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Keywords: | lacustrine pollen similarity coefficient Euclidean distance mixing effect |
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