Tallinn University of Technology

About: Tallinn University of Technology is a education organization based out in Tallinn, Estonia. It is known for research contribution in the topics: European union & Computer science. The organization has 3688 authors who have published 10313 publications receiving 145058 citations. The organization is also known as: Tallinn Technical University & Tallinna Tehnikaülikool.

Plant species richness belowground: higher richness and new patterns revealed by next‐generation sequencing

Abstract: Variation in plant species richness has been described using only abovegroundvegetation. The species richness of roots and rhizomes has never been compared withaboveground richness in natural plant communities. We made direct comparisons ofgrassland plant richness in identical volumes (0.1 · 0.1 · 0.1 m) above and below the soilsurface, using conventional species identification to measure aboveground richness and454 sequencing of the chloroplast trnL(UAA) intron to measure belowground richness.We described above- and belowground richness at multiple spatial scales (from aneighbourhood scale of centimetres to a community scale of hundreds of metres), andrelated variation in richness to soil fertility. Tests using reference material indicated that454 sequencing captured patterns of species composition and abundance with acceptableaccuracy. At neighbourhood scales, belowground richness was up to two times greaterthan aboveground richness. The relationship between above- and belowground richnesswas significantly different from linear: beyond a certain level of belowground richness,aboveground richness did not increase further. Belowground richness also exceeded thatof aboveground at the community scale, indicating that some species are temporarilydormant and absent aboveground. Similar to other grassland studies, abovegroundrichness declined with increasing soil fertility; in contrast, the number of species foundonly belowground increased significantly with fertility. These results indicate thatconventional aboveground studies of plant richness may overlook many coexistingspecies, and that belowground richness becomes relatively more important in conditionswhere aboveground richness decreases. Measuring plant belowground richness canconsiderably alter perceptions of biodiversity and its responses to natural andanthropogenic factors.Keywords: 454 sequencing, DNA barcoding, plant richness, root identification, speciescoexistence, trnL (UAA)Received 1 July 2011; revision received 7 October 2011; accepted 19 October 2011

The European Modern Pollen Database (EMPD) project

Abstract: Modern pollen samples provide an invaluable research tool for helping to interpret the quaternary fossil pollen record, allowing investigation of the relationship between pollen as the proxy and the environmental parameters such as vegetation, land-use, and climate that the pollen proxy represents. The European Modern Pollen Database (EMPD) is a new initiative within the European Pollen Database (EPD) to establish a publicly accessible repository of modern (surface sample) pollen data. This new database will complement the EPD, which at present holds only fossil sedimentary pollen data. The EMPD is freely available online to the scientific community and currently has information on almost 5,000 pollen samples from throughout the Euro-Siberian and Mediterranean regions, contributed by over 40 individuals and research groups. Here we describe how the EMPD was constructed, the various tables and their fields, problems and errors, quality controls, and continuing efforts to improve the available data.

Polar front shift and atmospheric CO2 during the glacial maximum of the Early Paleozoic Icehouse

Abstract: Our new data address the paradox of Late Ordovician glaciation under supposedly high pCO2 (8 to 22× PAL: preindustrial atmospheric level). The paleobiogeographical distribution of chitinozoan (“mixed layer”) marine zooplankton biotopes for the Hirnantian glacial maximum (440 Ma) are reconstructed and compared to those from the Sandbian (460 Ma): They demonstrate a steeper latitudinal temperature gradient and an equatorwards shift of the Polar Front through time from 55°–70° S to ∼40° S. These changes are comparable to those during Pleistocene interglacial-glacial cycles. In comparison with the Pleistocene, we hypothesize a significant decline in mean global temperature from the Sandbian to Hirnantian, proportional with a fall in pCO2 from a modeled Sandbian level of ∼8× PAL to ∼5× PAL during the Hirnantian. Our data suggest that a compression of midlatitudinal biotopes and ecospace in response to the developing glaciation was a likely cause of the end-Ordovician mass extinction.