Why decline in dung threatens mankind
The world is not only a less interesting place for the extinction of woolly mammoths, it is also becoming harder to farm, researchers claim.
The obliteration of almost every species of giant mammal over the past 100,000 years has all but wiped out a key nutrient cycle that once stretched from the bottom of the ocean to the steppes of central Asia. Researchers at the University of Oxford believe that whales, fish, seabirds and land-based megafauna were links in a chain that refreshed stocks of fertilisers such as phosphorus, which is expected to run out by the end of the century.
Smaller land mammals are not as efficient at distributing fertilisers over large areas as their larger relatives. The academics estimate that the natural chemical cycle has collapsed to six per cent of its former size.
Christopher Doughty, an Oxford ecology lecturer and the paper’s lead author, said that the chemicals were exposed as mountains were eroded. Rain washed the minerals into the oceans, where they were absorbed by tiny animals such as krill.
Dr Doughty and his colleagues wrote in Proceedings of the National Academy of Sciences that these nutrients were then spread across continents through a complex network involving whale excrement, fish, marine birds and land animals.
By 2050, there will be 9.7 billion people but farmers will be running out of basic minerals. Dr Doughty said whale excrement could play a pivotal role in the future of farming. He said: “If we could bring back the populations of marine mammals, we could improve the efficiency of this cycle.”
http://www.thetimes.co.uk/tto/environme ... 596999.ece
