Typically, an ecosystem can recover from changes and disasters on its own, but occasionally humans need to step in. One major reason that humans sometimes need to give nature a little help has to do with the amount of damage and the amount of time taken to cause such damage. Humans tend to create large scale disasters that happen far more quickly than nature can handle. Oil spills are a good example. If oil were to leak naturally from an ocean floor vent, it would likely happen so slowly that the ecosystem around that area could adapt. Oil spills that are man made happen much faster on a much larger scale. Humans often need to step in and try to save the ecosystem by cleaning wildlife, containing the spill, and other measures. Occasionally, humans step in for other situations as well. One example might be endangered species. Sometimes a species is endangered because of a problem humans have created such a habitat destruction. Other times it is a natural occurrence that simply moves too fast for nature to combat. One example might be the recent work with frogs. For some reason, a rare virus is attacking frogs around the world. We don't really know why but we know many ecosystems depend on frogs. Humans are trying to save as many species as possible. Nature could eventually fill the hole left by frogs if they did become extinct, but humans are stepping in to lend a hand.