Modern climate–vegetation–pollen relations in Africa and adjacent areas
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文摘
The pollen–climate and pollen–vegetation relation in Africa, Madagascar and Arabia has been investigated using 1170 modern pollen samples presently available in the African Pollen Database. Data are collected from different sedimentary environments (soil, lake, river, traps, midden, etc.). In spite of an irregular spatial distribution, there are representatives in all of the major vegetation and climate zones. Accounting for the different trapping efficiency of the different sediment types, large-scale patterns can be determined from the pollen assemblages. Maps and response-surfaces depicting the distribution in geographic and climate space of the main pollen types distinguish the major phytogeographic regions. Computing dissimilarities among the African pollen spectra using squared chord distance demonstrates that pollen spectra within a particular vegetation zone are more similar to one another that they are to pollen samples from other vegetation zones. Using the method of modern analogs, we find significant correlations between modern temperature and precipitation reconstructed using the best modern analog, which suggests the potential of this database for quantitative climate reconstructions. The study of individual pollen types provides an alternative method to the biomization to characterize and quantify the land-surface conditions at a continental scale.