Trees are one of the oldest living things on earth. They play a very important role for human’s existence. Trees are important for life as they provide food and oxygen. The importance of tree continues to increase and more benefits of trees are being discovered as their role expands to satisfy the needs created by our modern lifestyles. The forests and trees that are planted by humans work together with us to make the world look better and more beautiful.   Some of them are as follows.
Trees can clean soil and control soil erosion. Poisonous chemicals and pollutants from various factories enter into the soil, thus causing soil pollution.   Soil erosion is a serious problem that causes degradation (退化) of soil and leads to floods. Trees and plant roots bind the soil and thus reduce soil erosion. Also they conserve rainwater and reduce sediment(沉积) deposits.
Trees produce oxygen. Trees play an important role in reducing the greenhouse gases. They consume carbon dioxide and produce oxygen.   A fully grown tree produces oxygen which is sufficient for 10 people for a complete year. Also, they act as filters of the air that we breathe.
Trees are of commercial importance. Trees fulfill the need of fuel for cooking in many areas around the world. Trees also provide timber for furniture and hundreds of household items. Wood pulp is used for making paper in industries.   Some trees are even used to make medicines.
 ，They provide shelter and food for a number of animal species across the globe. Trees are especially important as they form green corridors connecting habitats with each other and with the countryside beyond.
This lowers global warming.
Trees have beautified our planet.
Trees act as the habitat for wild animals.
In fact, trees play different roles in our environment.
Without trees our planet cannot be considered a place for living.
Also, trees produce a number of fruits and nuts which are sold at market.
Trees have the ability to store them or change them into less harmful forms.
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