What do ecologists mean by 'ecosystem services'? Please provide and example
Ecosystem services are things that are done by nature that are tasks that we humans need to have done, and that we value. Some ecosystem services are rather obvious; examples would include the growth of crop plants, the natural replenishment of wild game and wild fish.
Other ecosystem services are more subtle; things such as pollination by wild bees and other pollinators, water filtering and cleansing, erosion control - but are equally important. While everyone agrees that these services are necessary and valuable to the human race, there is much controversy about whether - or even if - we should be trying to place a dollar value on ecosystem services.