Failed pollen analyses in the Iberian Peninsula are so numerous as to suggest that there may be something intrinsic to this region that is inimical to the preservation of palynomorphs. Is the huge mass of calcium carbonate represented by the Iberian Peninsula somehow related to palynological sterility? Is the prevailing aridity/summer drought a limiting factor? Peat bogs are not abundant, but lakes are widespread, although many are saline and not a few experience periodic desiccation and strong oscillations of the water table. These are, doubtless, factors linked with oxidation processes. Equipment to drill permanent lakes is expensive, limiting access to depositional centres of continuous sedimentation. Only during the last decade have funding and co-operation allowed both Spain and Portugal to carry out deep lake drilling within national and international research programmes. For example, during three months in 2004, the Pyrenean Institute of Ecology (IPE)-CSIC carried out, for the first time in Spain, a large drilling expedition (LIMNOCLIBER) throughout the Iberian Peninsula in collaboration with the Limnological Research Centre (LRC) of the University of Minneapolis (USA), with a final result of more than 200m of lacustrine sediments from eight Spanish lakes. Yet a number of possibly useful lakes and marshlands have not even been drilled. An example is the Laguna de La Janda in Cádiz, one of the more extensive tectonic depressions of Iberia (Dueñas and Recio 2000), where, to our knowledge, no palynologist has yet ventured. Further cases come from the mountains, like Sierra Nevada, the Cantabrian Mountains and the Pyrenees, where high-elevation lakes appear suitable for palaeoenvironmental studies. Problems of accessibility persist for some basins, but the potential is still there. The high number of endorheic lakes in La Mancha provinces of Albacete, Ciudad Real, and Cuenca, even Jaén in Andalucía, should not be neglected in spite of the discouraging results of Pétrola, Ontalafia, and El Acequión in Albacete. Many are low-salinity and nearly permanent, and peat deposits are sometimes preserved at their margins (Cirujano 1990; Casado and Montes 1995). The region contains archaeological and coprolite sites in abundance but the former often fail to contain pollen, and the latter have been insufficiently tested.
It is also worth wondering whether failures with pollen analysis have been equally common in other territories, but have simply not been reported. Collecting the data presented here has been time-consuming, and no doubt some would regard such an exercise as producing little career reward for the effort. Apart from the severe difficulties in getting active collaboration, there have been cases among the contributors where the laboratories have been demolished, or where the researcher has been moved and the original processing sheets have been impossible to rescue. So, with fragmentary information, we are aware that this work is incomplete in many aspects and needs further detail before we can achieve more far-reaching conclusions. This is a first step only. The next step is to stimulate future controlled investigation of negative results, a more multidisciplinary approach, more frequent collaborative research between palaeoecologists, and, necessarily, a more realistic assessment among Quaternary specialists of what information palynology can give and what it is unable to deliver.
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Last updated: Mon Feb 23 2009