When wolves were reintroduced to Yellowstone National Park in the United States after being absent nearly 70 years, the most remarkable "trophic cascade" occurred. What is a trophic cascade and how exactly do wolves change rivers?
Posted 10 years ago by tommee in category: animals   Comments (0)



World record pole vault at 6.16 m by Renaud Lavillenie at Donetsk (Ukraine). Previous record was held by Sergei Bubka for 21 years.
Posted 10 years ago by ginoongpedro in category: sports   Comments (1)