科研之友
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摘要
The representation of pollen and spores in the fossil record of late Quaternary sedimentary sequences depends on several factors, including the production and dispersion of pollen grains. Thus, the analysis of modern pollen rain contributes to the understanding of these factors and to the knowledge of how vegetation is represented in the fossil pollen spectra. Modern pollen rain from eight vegetation types along an altitudinal gradient from 2300 +/- 4329 masl in the basin of Mexico are analyzed by using different statistical methods. Pollen spectra from high elevation plant communities > 380 ($) over bar0 masl were divided from low altitudes by applying cluster analysis. Based on pollen composition, this study uses DCA to distribute the plant communities in an altitudinal gradient, and probability density functions (PDF) are used to describe the distribution of pollen along the altitudinal gradient. Pollen taxa with low percentages characterize the low altitude sites, with PDFs similar to the parental taxa. Pinus, Poaceae and Asteraceae show wide altitudinal ranges and their PDFs reflect a pattern comparable to the parental taxa, while Quercus, Alnus, Salvia and Salix with narrow altitudinal ranges have PDFs that indicate pollen transport to higher altitude sites. The presence of Mimosa, which present a well defined PDF, can be used as an indicator of paleoenvironmental conditions in the fossil pollen sequences in the basin of Mexico.
- 出版日期2014
