Palynology and pollen preservation

Abstract

Despite the fact that pollen analysis is very often applied to sediments with poorly preserved pollen, pollen and spore corrosion is a greatly neglected subject in palynological research. Lack of knowledge about susceptibility to decay of the individual pollen or spore species may easily lead to misinterpretation of pollen diagrams. Pollen corrosion is a very complex concept, comprising the effect of various external factors (microbial attack, oxidation, mechanical forces, high temperature) as well as factors inherent to the pollen grains or spores themselves (sporopollenine content, chemical and physical composition of the pollen or spore wall). A special study is needed for a proper appreciation of the influence of each of these factors. The author applied experimental laboratory and field research to twenty pollen and spore species. The study includes research on differential susceptibility to chemical oxidation and microbial attack in various soil types. Investigations were also begun on microbial attack under laboratory conditions. It was found that a parallel exists between differential susceptibility to oxidation and differential susceptibility to decay in a natural environment, insofar as the latter was established from written evidence. These data refer to soils with poor biological activity. Corrosion tests, however, showed that differential susceptibility to corrosion of several pollen species is quite different in soils rich in this respect. This is connected with the corrosion effect of the perforation type mainly found in this type of soil. An investigation of some fossil podsol profiles revealed the frequent occurrence of pollen with a perforated exine in one of them. The theory adduced is that the perforations mainly originate from a phase of soil formation, preceding the present profile, which had a rich biological activity. The soil podzolized rapidly and then submerged, so that the corrosion phenomena were “fossilized”.