Ecosystems provide people with a variety of benefits, ranging from 'goods' such as food, water, fuel and timber, through services such as flood mitigation, climate regulation, and maintenance of soil fertility, to less tangible things such as spiritual and aesthetic well-being.The supply of these benefits, collectively called 'ecosystem services', is affected by policies, decisions and actions at all scales, from the local to the global. Decision-makers often face challenging decisions about tradeoffs between ecosystem services and other aspects of human welfare, as well as among different ecosystem services, without having access to the best available information.