Until now, modern governments and businesses have treated the Earth as a commodity to be exploited and used up to serve human needs and desires. Our whole economic system is built on the belief that a thing is only of value if it creates money.
By these standards a forest is worthless unless it is cut down and sold. When economists balance the books, they don't take into account the value of the work that forests do to provide rainfall, regulate the climate and provide habitat for most of the world's plants and animals, not to mention food and shelter for millions of local people.