Pollen analysis has been, and still is, one of the most widely used techniques in Quaternary sciences, especially to reconstruct vegetation history and climate variability. Fossil deposits of accumulating plants, such as peat sediments, were very early investigated as they are particularly suitable for the reception, storage and conservation of palynomorphs. Thanks to successive methodological innovations, palynological analyses then gradually developed by multiplying studies of diverse more mineral sedimentary materials (lake, stream and/or marine sediments, loess deposits, travertine, etc.). These new efficient techniques also led to an interest in archaeological sediments, allowing palaeoenvironmental reconstructions where no adequate Quaternary continental sedimentary records are available. Soon after the mid-20th century, caves and rock-shelters became then the favored studied places in karstic areas to approach the environment of prehistoric humans. However, the pollen record in caves is a complex phenomenon in which multiple geological, biological and atmospheric factors are involved and could lead to some distortions and discontinuities in the pollen assemblages. When not perceived, these pitfalls have sometimes generated some over or misinterpretations. After a keen interest, cave sediment sequences were thus considered as unattractive, presenting lot of alterations, difficult to correlate and with a low palaeoenvironmental potential. The validity and scope of the interpretation of palynological data from this type of deposits are still highly controversial and debatable. In Belgium, a systematic program of detailed stratigraphic recordings from caves associated with various palaeoenvironmental analyses has recently been undertaken in close collaboration with researchers from different disciplines. The objective was to better understand the sedimentary dynamics of these fillings and to test their potential as recorders of Quaternary climatic variations. In that context, new pollen data from two Belgian caves have been acquired and open new prospects for research work in this type of environments. In this paper, we present the state of the art of cave palynology, including the different parameters defining pollen taphonomy, the potentials and the limits of pollen analysis on Quaternary cave deposits. Through the examples of the caves Walou and Scladina, we show that good palynological results can be obtained in these contexts. These records are compared and evaluated in the light of multidisciplinary palaeoecological information from these two prehistoric settlements. When precautions are taken and a close link with geology and archaeology is maintained, local environment of the prehistoric populations, but also major trends in vegetation evolution and climate change during the Middle Paleolithic, can be accurately documented by pollen records from cave sequences.
Located in
Library
/
RBINS Staff Publications
Scientific institutions like museums maintain large collections enabling present and future research. Thanks to the digitization of the collections, in most of these institutes, it enables researchers across the globe to see which collections might be interesting for their projects. However as most of these databases only provide descriptive information and/or metadata, it remains impossible to study these digitized specimens from a distance. As the most precious parts of the collections, like type specimens, are the most requested ones by fellow researcher, these become, inevitably, the most handled ones. Unless a policy exists not to handle them at all, which unfortunately, prevents research. To make sure that collection material like type specimens remain documented for future research and can be studied trough the internet, digitization is the key, 3D or 2D. The only challenge is to chose the right digitization method for the right material and or size (Mathys et al., 2013). Especially small specimens which are often found in insect and invertebrate collections tend to be difficult to digitize in 3D as fine structures can only be seen in µCT recordings, which are still quite expensive pieces of equipment. However, 2D image might provide enough information to conduct for instance taxonomic research. Image stacking is the only way to capture enough detail in a single picture as the low depth of field of camera lenses, makes it almost impossible to get the complete object in focus, unless the aperture is stepped down. However this results in other aberrations as the optical resolution reduces due to the diffraction effect. Thanks to the large computational power of today’s workstations, it is possible to do image stacking rather easily. The only remaining challenge is taking the individual pictures. Readily made commercial stacking columns do exist, but are too expensive to provide one to each department or research group. In this paper we will present the results of a low cost approach consisting of a DSLR camera attached to an automated macro rail with a custom build light tent. As there are no over- or underexposed parts on the resulting images, they are good enough to allow publication without the use of a post-processing software. More importantly, during the photo-shoot of one specimen another can be prepared, alcohol based or dry, for the next shoot. When similar specimens are digitized at the same time, light and aperture settings stay more or less the same, providing a fast and smooth workflow. The stacking of the images, done in Zerene Stacker, can easily be started as a batch process at the end of the working day or during the night. As the total package of this system can be purchased for around € 2.5k several digitization centers can be started in different department allowing faster digitization of the type material.
Located in
Library
/
RBINS Staff Publications
