Palynology is one of the most widely used research tools in Quaternary studies (Edwards 1983). Faegri and Iverson (1989, p. 1) define pollen analysis as ‘a technique for reconstructing former vegetation by means of the pollen grains it produced’. While palynology technically refers to the study of both pollen grains and spores, these will be referred to collectively as ‘pollen’ for the sake of convenience. Pollen analysis has been used to document long-term vegetation dynamics ever since the success of von Post’s pioneering experiments in 1916 (Birks 1993). The basic assumption of the technique is that the number of pollen grains deposited per unit time, at a given point, is directly related to the abundance of the associated species in the surrounding vegetation (Davis 1963). However, pollen data are presented as proportions of a total pollen sum, rather than as discrete numbers (Davis 1963). Therefore, difficulties with the representivity both between and within species are experienced, as some taxa produce far greater quantities of pollen, which are more widely dispersed than others (Birks and Birks 2005). In other words, pollen data require careful interpretation as the representivity of the pollen spectrum is shaped by differences in pollen productivity, dispersal and preservation (Faegri and Iverson 1989). Pollen grains are well suited to analysis for a number of reasons: (i) they have extremely resilient exines, which allow for their survival in deposits where other fossil types have been destroyed; (ii) they are abundantly produced; (iii) they are widely and evenly dispersed; and (iv) pollen data are easily quantified (Faegri and Iverson 1989).

It is useful to think of pollen analysis as a remote sensing instrument, which records the past and present composition of vegetation (Webb et al. 1978). As with any sensing instrument, pollen analysis has certain response characteristics, which limit its application to certain contexts (Prentice 1988). Pollen data have been used in a wide variety of Quaternary applications including chronostratigraphic correlation, palaeoecology, palaeoclimatology and archaeology (Macdonald 1988). Data derived from pollen studies can be used to provide an indication as to the response of natural vegetation to human impacts through history, as well as to climatic and environmental change (Prentice 1988; Edwards and Macdonald 1991). Birks (1981) attributes the importance of the pollen record as a source of palaeoclimatic information to both its length (102 – 105 years) and sample resolution (10 – 1000 years). At the largest spatial scale, pollen data have been used to reconstruct past changes of biomes, using pollen records from entire modern biomes as a basis (e.g. Jolly et al. 1998; Elenga et al. 2000). In addition, Quaternary palynological data constitute a valuable quantitative record against which climatic models such as general circulation models (GCMs) can be validated, for studies of global change (Huntley 1990). These data strengthen predictions of how vegetation is likely to respond to future climatic conditions, thereby providing an indication of the future agricultural and silvicultural potential of various regions (Huntley 1990).

 

General Principles

Birks and Birks (1980) have outlined the general principles of pollen analysis as follows: (i) pollen grains are produced in large quantities during the natural reproductive cycles of many plants; (ii) relative vegetation composition can therefore be inferred from the pollen grains released into the environment, as these are a function of the number of parent plants; (iii) the majority of pollen grains produced by plants never fulfil their reproductive function, and when deposited within sediments they may be preserved as fossils; (iv) fossil grains may be extracted from sediments and identified down to family/genus/species level; and (v) the stratigraphic level at which grains are extracted corresponds with particular periods in the past.

 

Figure 1. Examples of pollen reference slides from South Africa
 

References

Birks, H. H. and Birks, H. J. B. (2005): Reconstructing Holocene climates from pollen and plant macrofossils. In: A. Mackay, R.W. Battarbee, H.J.B. Birks and F. Oldfield (eds), Global change in the Holocene, Hodder Arnold, London, pp. 342-357.

Birks, H. J. B. (1981): The use of pollen analysis in the reconstruction of past climates: a review. In: T.M.L. Wigley, M.J. Ingram and G. Farmer (eds) Climate and history. Studies in past climates and their impact of man, Cambridge University Press, Cambridge, pp. 111-138.

Birks, H. J. B. (1993): Quaternary palaeoecology and vegetation science - current contrubutions and possible future developments. Review of Palaeobotany and Palynology, 79, 153-177.

Birks, H. J. B. and Birks, H. H. (1980): Quaternary palaeoecology, Edward Arnold, London.

Davis, M. B. (1963): On the theory of pollen analysis. American Journal of Science, 261, 897-912.

Edwards, K. J. and Macdonald, G. M. (1991): Holocene palynology: II Human influence and vegetation change. Progress in Physical Geography, 15, 364-391.

Elenga, H., Peyron, O., Bonnefille, R., Jolly, D., Cheddadi, R., Guiot, J., Andrieu, V., Bottema, S., Buchet, G., Debeaulieu, J., Hamilton, A., Maley, J., Marchant, R., Perezobiol, R., Reille, M., Riollet, G., Scott, L., Straka, H., Taylor., D., van Campo, E., Vincens, A., Laarif, F. and Jonson, H. (2000): Pollen-Based Biome Reconstruction for Southern Europe and Africa 18,000 Yr BP. Journal of Biogeography, 27, 621-634.

Faegri, K. and Iverson, J. (1989): Textbook of pollen analysis, John Wiley & Sons, Chichester.

Huntley, B. (1990): Studying global change: the contribution of Quaternary palynology. Palaeogeography, Palaeoclimatology, Palaeoecology, 82, 53-61.

Jolly, D., Prentice, I. C., Bonnefille, R., Ballouche, A., Bengo, M., Brenac, P., Buchet, G., Burney, D. A., Cazet, J.-P., Cheddadi, R., Edorh, T. M., Elenga, H., Elmoutaki, S., Guiot, J., Laarif, F., Lamb, H. F., Lezine, A. M., Maley, J., Mbenza, M., Peyron, O., Reille, M., Reynaud-Farrera, I., Riollet, G., Ritchie, J. C., Roche, E., Scott, L., Ssemmanda, I., Straka, H., Umer, M., Van Campo, E., Vilimumbalo, S., Vincens, A. and Waller, M. (1998): Biome reconstruction from pollen and plant macrofossil data fro Africa and the Arabian peninsula at 0 and 6000 years. Journal of Biogeography, 25, 1007-1027.

Macdonald, G. M. (1988): Methods in Quaternary ecology #2. Palynology. Geoscience Canada, 15, 29-42.

Prentice, I. C. (1988): Records of vegetation in time and space: the principles of pollen analysis. In: B. Huntley and T. Webb III (eds), Vegetation History, Kluwer Academic Publishers, Dordrecht, pp. 16-42.