A price on ecosystem?

Ecosystems are life systems. You cannot put monetary value of life systems. How can you put a money value on something like air? But increasingly there is talk of placing a value on the eco-system. IS it because we have reached a point where unless a monetary value is placed on somehting, we do not value it. Take for instance trees. Our cities are shedding trees at a rapid pace as they give way to buildings and roads. And yet, we recognise the value of a tree when caught on a hot day on the roadside. People park cars under the shade of a tree, but do not spare a thought for a tree facing the axe. Guess what trees do for us beyond the irreplaceable belching out of oxygen. They keep the concrete and asphalt of cities and suburbs 10 or more degrees cooler and protect our skin from the sun’s harsh UV rays. Loss of trees means that many millions invested in air-conditioning. Trees, also sequester carbon, a greenhouse gas that makes the planet warmer. A study by the Carnegie Institution for Science also found that water vapor from forests lowers ambient temperatures. “Working trees” could absorb some of the excess phosphorus and nitrogen that run off farm fields and help heal the dead zone in the Gulf of Mexico. In Africa, millions of acres of parched land have been reclaimed through strategic tree growth. Trees also release vast clouds of beneficial chemicals. On a large scale, some of these aerosols appear to help regulate the climate; others are anti-bacterial, anti-fungal and anti-viral. We need to learn much more about the role these chemicals play in nature. A walk in the woods, they say, reduces the level of stress chemicals in the body and increases natural killer cells in the immune system, which fight tumors and viruses. Studies in inner cities show that anxiety, depression and even crime are lower in a landscaped environment. A 2008 study by researchers at Columbia University found that more trees in urban neighborhoods correlate with a lower incidence of asthma. The list goes on. Yet, we need monetary schemes to spur afforestation. What's your take?