One of those dying in large numbers is Pennsylvania's state tree, the Eastern Hemlock, under attack by a bug called the woolly adelgid. Florida's state tree, the Cabbage palmetto which is shared with South Carolina is healthy and seems secured. The virtues of trees are many. Their soaking up of carbon dioxide with subsequent returns of oxygen is phenomenal. Their leaves are just about the greatest dust catchers around, sound attenuates or noise absorbers, and even when the leaves drop, in spite of the leaf rakers, they would provide their own re-fertilization and water retention with the resultant mulch.
Trees are responsible for many natural amenities.
Here are some statistics. The net cooling effect of a young healthy tree is equal to ten room-size air conditioners operating 20 hours a day. Trees can boost the market value of your home by six to ten percent, and landscaping with trees can increase property value by as much as 20 percent. One acre of forest absorbs six tons, that's 12,000 pounds of carbon dioxide, and puts out four tons of oxygen. This would take care of the oxygen needs of 18 people for a year.