Wednesday, March 18, 2015

Possible Early Dry-Land and Wet-Land Rice Cultivation in Highland North Sumatra

Possible Early Dry-Land and Wet-Land Rice Cultivation
in Highland North Sumatra

TRADITIONALL Y POLLEN ANALYSTS have only examined pollen and concentrated in particular upon what changes in the tree pollen curves indicate about local and regional vegetation change. Having tracked this, they have made deductions about how swamp and lake-margin vegetation has varied in relation to natural progression or retrogression over time and made palaeoclimatic deductions and deductions about human use of the land. More recently attention has been focused rather more on what the nonarboreal component of each pollen spectrum reveals, and now people are beginning to recognize that the pteridophyte record might also indicate how climate has changed and give signals to possible past anthropogenic activity. Additionally it is becoming increasingly recognized that the analyst must do more than attempt to explain the fluctuations in the pollen and spore records. It is also desirable to count other microfossils that may be present, and these include the biogenic silica (phytoliths, which only a very few people can identify expertly), the algae, microfossil charcoal, leaf cuticular remains, microscopic volcanic ash, and the like. Complete Southeast Asian pollen diagrams alone often contain a very large number of taxa, many of which are ecologically uninformative. The Pea Bullok cores to be mentioned later contained 355 identifiable types in the 70 samples analyzed so far, and other types not yet found in samples from that site are present in those from the other three sites that will be mentioned (Pea Sim-sim, Pea Sijajap, and Tao Sipinggan), despite the fact that they are situated fairly near each other. To present the full data set to nonexperts would be futile, as the pertinent information concerning what the records indicate about vegetation change would be lost in the wealth of technical detail. It is, of course, desirable that the full data set should either be published or submitted to a data bank and be made available to other specialists in due course, and I hope to do this when time permits.


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