Read the passage below and answer the question that follows. 'Planting trees is one of the cheapest and most effective actions a community can take. Trees absorb carbon dioxide and release oxygen, which improves the quality of the air we breathe. Their roots hold the soil together and prevent the erosion that has swallowed farmland and houses in parts of Anambra and Enugu. Their shade lowers the temperature of streets and compounds, reducing the need for fans and air conditioners. Trees also provide food in the form of fruits and nuts, and materials such as timber and firewood, when they are harvested responsibly. In towns, well-placed trees increase the value of property and provide a habitat for birds and insects. Yet in many Nigerian communities trees are felled for firewood or to make room for buildings far faster than they are replaced, and the newly planted seedlings that survive Arbor Day photographs are seldom watered afterwards.' In four sentences, one for each, summarise the benefits of planting trees mentioned in the passage. (20 marks)