A mammoth metadata study of 111 different papers concludes that “biodiversity matters”. Well, duh. But it is good to have data. The study is published in Nature (press release here) for 25 October. To demonstrate the value of biodiversity, the study’s author Bradley Cardinale chose a paper that shows that the presence of three aphid predators has a greater impact on pests than one would expect from each of the three alone. In a single state — Wisconsin — this pesticidal service was worth millions of dollars, Cardinale said. Not to dismiss all the other services that biodiversity performs, but it seems that one way to get decision makers to understand its importance is to turn those nebulous “services” into something they do understand: cold hard cash.