Although they have persisted for tens of millions of years, neotropical lowland forests have changed greatly in extent and composition due to climatic variation and to human impacts. In a symposium at the 2002 meetings of the Association for Tropical Biology, hosted by the Smithsonian Tropical Research Institute (STRI), Panama, scientists presented the latest results of research on neotropical forests and their transformations up to the time of Columbus.
Bruce MacFadden, of the University of Florida, has re-examined a mammal fossils of mid-Miocene age (18-16 million years ago) collected in central Panama in the 1960s, but not previously described in detail. At the time a deep oceanic channel across eastern Panama separated North and South America. Although the species are closely related to those of North America of the same age (instead of geographically closer South America), most appear to have been adapted to forested habitats, rather than being grasslands species like those that dominated North America. In particular, the low-crowned teeth of herbivores reveal that they fed on soft-leaved forest vegetation rather than grasses, and future analysis of carbon isotope ratios in enamel may further confirm this.
Lake cores are increasingly being used to obtain records of pollen, phytoliths, charcoal, and other evidence of forest distribution and composition from throughout the neotropics over the past 20,000 years. Dolores Piperno, of STRI, described how this data shows colder, drier conditions than those of the present prevailed in many areas in the late Pleistocene. In some areas forests persisted, although they often contained a mix of lowland species with those found only at higher elevations today, creating tree communities quite different from modern ones. In others, grassland replaced forest. Later, after the arrival of humans, forests gradually retreated with the spread of slash-and-burn agriculture, only to return again when indigenous populations were decimated after colonization by Europeans. Barbara Leyden of the University of South Florida presented data from lake cores from the Yucatan Peninsula. Although stable isotopes identified a severe drought at the end of the Mayan Classic Period, the pollen record showed the vegetation was not greatly affected except for maize and associated weedy species.
Dolores Piperno | EurekAlert!
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...
Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...
Scientists from the MPI for Chemical Energy Conversion report in the first issue of the new journal JOULE.
Cell Press has just released the first issue of Joule, a new journal dedicated to sustainable energy research. In this issue James Birrell, Olaf Rüdiger,...
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