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!
Emissions from road construction could be halved using today’s technology
18.05.2020 | Schwedischer Forschungsrat - The Swedish Research Council
When every particle counts: IOW develops comprehensive guidelines for microplastic extraction from environmental samples
11.05.2020 | Leibniz-Institut für Ostseeforschung Warnemünde
Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.
When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...
Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.
Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...
Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.
A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...
By studying the chemical elements on Mars today -- including carbon and oxygen -- scientists can work backwards to piece together the history of a planet that once had the conditions necessary to support life.
Weaving this story, element by element, from roughly 140 million miles (225 million kilometers) away is a painstaking process. But scientists aren't the type...
Study co-led by Berkeley Lab reveals how wavelike plasmons could power up a new class of sensing and photochemical technologies at the nanoscale
Wavelike, collective oscillations of electrons known as "plasmons" are very important for determining the optical and electronic properties of metals.
19.05.2020 | Event News
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06.04.2020 | Event News
25.05.2020 | Medical Engineering
25.05.2020 | Information Technology
25.05.2020 | Information Technology