Pollen Database Research Articles

An Expanded Recent Pollen Database from South-eastern Australia and its Potential for Refinement of Palaeoclimatic Estimates

Seventy-one pollen spectra from prior to the period of European impact were extracted from fossil pollen diagrams on mainland south-eastern Australia in 1991 to use as a modern reference for refinement of vegetation and climatic histories constructed from the region. This paper presents results of an extension of this recent database to 135 spectra, derived from additional fossil pollen sites on the mainland and also from sites in Tasmania. The sites include those of almost all late Quaternary pollen studies ever undertaken. Estimates of climate for each site, derived by BIOCLIM, have allowed an examination of patterns of representation of individual recorded taxa in relation to regional variation in major climatic parameters. Pollen taxa show variable representation in relation to their inferred presence and abundance in parent vegetation due to differential pollen production and dispersal characteristics. However, patterns of pollen representation do appear to relate, in broad terms, to climatic variation. It is considered that this modern pollen and climate database should lead to more certain interpretation of future pollen records including some quantification of palaeoclimatic conditions.

Ice Age terrestrial carbon changes revisited

N. Shackleton (1977) first proposed that changes in the marine δ13C record (Δδ13C) could be used to infer ice age changes in carbon storage on land. The previously published best estimate from the marine record is equivalent to about 490 Gt (0.32 Δδ13C). However, Adams et al. (1990) utilized a pollen database to estimate a 1350 Gt change in carbon storage, which would cause a Δδ13C of about 0.90‰. The nearly trillion ton difference in estimates amounts to almost half of the total carbon stored on land. To address the nature of this discrepancy, I have reexamined the terrestrial carbon record based on a new pollen database compiled by R. Webb and the Cooperative Holocene Mapping Project (COHMAP) group. I estimate about 750–1050 Gt glacial‐interglacial change in terrestrial carbon storage, with the range reflecting uncertainties in carbon storage values for different biomes. Additional uncertainties apply to rainforest and wetland extent and presence of C4 plants, which have a significantly different isotopic signature than C3 plants. Although some scenarios overlap a new estimate of carbon storage based on the oceanic Δδ13C record (revised to 0.40‰ and 610 Gt), most estimates seem to fall outside the envelope of uncertainty in the marine record. Several possible explanations for this gap involve: (1) a missing sink may be involved in land‐sea carbon exchange (e.g., continental slopes); (2) the geochemistry of the exchange process is not understood; (3) carbon storage by biome may have changed under ice age boundary conditions; or (4) the standard interpretation of whole ocean changes in the marine δ13C record requires reevaluation. This latter conclusion receives some support from comparison of the δ13C records for δ18O Stages 2 and 6. For the Stage 6 glacial, the δ13C changes are 50–60% larger than for the Stage 2 glacial. Yet implications of increased aridity are not supported by longterm trends in atmospheric dust loading. To summarize, the above analysis implies that, despite the uncertainties remaining in estimates of terrestrial carbon storage changes, a case can be made that our understanding of the transfer process is incomplete and that the eventual explanation may require clarification of factors affecting the marine δ13C record.

RADAR, a relational archaeobotanical database for advanced research

The structure of the Dutch Relational Archaeobotanical Database (RADAR) is presented. RADAR is a rather compact archaeobotanical database that is controlled centrally, but can be distributed to individual scientists. For this reason RADAR contains only the most important archaeobotanical data. For detailed archaeological, botanical and regional palaeoenvironmental information, links can be established with the national archaeological database (ARCHIS), the national botanical database (BBR) and the European Pollen Database (EPD). The software used for manipulation of the database is PARADOX for reasons of its highly visible nature, its control facilities for data entry and the ease of importing and exporting data from and to many other programs. The potential of the database is demonstrated with query examples.

Pollen flight forecasting in Germany and in Europe.

Every tenth person in Central Europe is a pollinosis patient. The time of ripening and release of pollen, as well as pollen flight, all depend on the weather. Because each year is different from every other, mean values from pollen calendars do not provide any practical help for allergy-sufferers. For this reason, in many European countries, measuring networks have been established during the last 10 years as a basis for forecasting the prevalence of airborne pollen for the following 2-3 days, in connection with the weather forecast. Cooperation and communication also exist on a European level, and a European Pollen Database had been established.

The “Zavada hypothesis”: a rebuttal rebutted

SummaryGibbs, P.: The “Zavada hypothesis”: a rebuttal rebutted. ‐ Taxon 40: 583–595. 1991. ‐ISSN 0040‐0262.The Zavada hypothesis, that there is a correlation between the various types of self‐incompatibility mechanisms found in angiosperms and details of pollen exine sculpturing, is addressed again. In the light of a recent further defence of the hypothesis, some errors in the original data on which it was based are considered, and some criticisms by Zavada of a different data base are discussed.

Methodology of the last climatic cycle reconstruction in France from pollen data

A numerical method has been devised to reconstruct the climate of the last climatic cycle from pollen data. Reliable annual reconstructions have been published recently for the two French long sequences of La Grande Pile and Les Echets covering the last 140 millennia. This paper gives more details on the method used. It proposes new reconstructions based on an extended modern pollen data base. These reconstructions are consistent with the previous ones. Especially, detailed information is obtained on the seasonal characteristics of climate. Computations of GCM on the climate variations from 125 kyr to 115 kyr B.P. are confirmed for Western Europe. The insolation variations have induced at that time a decrease of seasonality accompanied by an increased cyclonic activity in winter. This has been the beginning of the first ice growth after the Last Interglacial. Other glacier growth phases are detected at the end of Substage 5c and particularly at the end of Substage 5a.