Trees are Valuable | Benefits from Growing Trees

The average lifespan of a tree is 100-200 years. Some may live live less, but many can survive considerably longer (even thousands of years). 

During the photosynthesis process tall green plants take in carbon dioxide and give off oxygen. Trees help to maintain the low levels of carbon dioxide. This in turn reduces the greenhouse effect. Primitive plants converted the poisonous atmosphere of the early earth into one rich in oxygen, able to support animal life.
The trees also benefit the soil because their extensive roots hold the soil in place, preventing erosion. The trees also improve the soil quality because the falling leaves make perfect compost.
There are some trees, like Acacia spp. and Allocasuarina spp., with bacteria (called rhizobia) in their roots. These bacteria convert nitrogen in the air into nitrates which the tree can use to grow and reproduce. The soil is also enriched by these nitrates.
Leaves, flowers and fruit, and sometimes bark are eaten by a range of animals in various countries. These break down in the animal's gut and eventually return to earth as manure - compost. Seed is dispersed by animal faecal deposits.
Trees provide nest sites for birds. In the leafy branches there are good hiding places, difficult for most predators to reach. Very large, old trees sometimes develop hollows interior which become favourites breeding and roosting places for bats, birds & marsupials. Even rotting wood and bark provides food for insects.
The Commercial Value of Trees
Timbers are widely used for buildings due to strength, lightness and variable endurance. Timber is also used for the manufacture of furniture, sports equipment, tool handles, match sticks, etc. Paper is made from pulped wood.
Man's first fuel was wood and it remains the main energy source for many people around the world. Sawdust and cut-offs are important by-products. They are a vital fuel in industry and may be processed to produce chemicals and alcohol.
Some trees provide bark which can be used as cork, and some bark can also be made into simple cord. Bark's main importance is as a source for chemicals and medicines. Tannin, the basis of the leather tanning industry, was derived from wattle bark. Bark and many other parts of the tree are used in the production of traditional and modern medicine. Aspirin and quinine were both made from bark extracts.
The inner bark of certain trees provides latex, the main rubber ingredient. Acacia trees provide sap used to manufacture gum. The maple trees of North America give off an edible maple syrup. There are several palms with watery sap to drink as palm wine. Alternatively it can be fermented and distilled into a powerful spirit. Plus there are the edible fruit: lychees, mangoes, walnuts, pecans, apples, oranges, plums, pawpaws, lillypillies, etc.
Trees provide shelter from the sun for both man and beast. On hot climates the shade of trees is essential. Trees are often planted to provide windbreaks for sensitive crops and for grazing animals.
Trees also have aesthetic value to which a monetary value cannot be attached. Trees add beauty to the environment. Some are tall and thin. Others have fat tops and they spread out and cover a large area. Leaves come in a variety or shapes and sizes, and the flowers and fruits are often decorative.