The tiger. The protection of big allrounders like tiger, wolf or lion may play a key role in ecosystem stabiltiy (photo: U.S. Fish and Wildlife Service)

Computer models can contribute to the understanding of complex systems in nature. Ecosystems belong to complex systems which are influenced by numerous correlated factors. Food chains for example are part of ecosystems and difficult to investigate in all with the methods of field ecology. It is known that food webs are stable over long time periods, the interactions between different species (predators and prey) are constant. Yet when ecologists try to calculate models of such correlations they face some obstacles: they have to reduce usually many factors to get reasonable scientific output from their models. So still conclusions drawn from results are still constrained. Now scientists from Austria, Germany and the US revealed fundamental legalities of stability in ecosystems: the more diversified the prey species are on which a predator at the top of a food chain feeds the more stable is the ecosystem in which it lives. Accordingly a food chain is most stable if the prey species in the center of a food web or a food chain have various predators. The scientists used a new method  developed by a workgroup of the Max-Planck-Institute of the Physics of Complex Systems.

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Windfarm in England. Photo from Wikimedia Commons (courtesy of Charles Cook)

That energy can be harnessed from the wind is not a new discovery. The first practical windmills were developed in Persia in the 9th Century and large windmills used for grinding grain were common in medieval Europe. It is, though, first with the development of modern wind turbines that significant amounts of energy can be produced. Today wind energy is widespread and still growing in use throughout the world. However, the fraction of energy being produced by wind turbines is still very modest. Denmark is one of the frontrunners in the development and usage of wind generated energy, but even there wind energy only contributes with around 20% of the country

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 "In the year 6565, if man is still alive" was the text of a famous pop song of the seventies and in a Science-fiction-movie of the nineties ("Waterworld") Kevin Kostner portrayed a aquatic world in a fictive future in which the survivors of a global climate change mainly live on the water and former cities like New York, Hamburg or London are beneath the shore of the oceans. It seems as if mankind is on its best way to fullfill darkest visions: in a recent study German and British scientists from the University of Tuebingen, University of Southhampton and University of Bristol developed a model which predicts the rise of the sea level for the coming millenia. Their conclusion: in some thousand years Earth will have a sea level alike in the pliocene (3-5 million years ago).

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A maple seed with the heavy nut at the base and the wing shaped seed at the top. Photo courtesy of Wikimedia Commons (by user Kobako).

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The small male approaching the much larger female of the golden orb spider, Nephila clavipes. Photo: T. Hesselberg.

A new study explains the observed size difference between females and males (sexual dimorphism) in spiders by referring to gravity. Gravity gives rise to an optimal size above where climbing speed is reduced. Since male spiders are often required to climb to access females located in their webs in the vegetation, large spiders should thus have larger sexual dimorphism. The scientists were able to show that this is true for a wide range of different spiders.

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Fat Schorsch - advertisement for a german pub (1904)

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