Here are some points which you may expand for the essay:

- Life without trees would reduce oxygen levels very badly and would end up in suffocating and killing many people.

- It would reduce human population.

-It would make the colour 'green' endangered.

-It would make all lands look the same - like deserts.

-It would reduce rainfall in the land.

- It will take away the home of many terrestrial organisms.

- It will cut down the food chain of living beings.

- It would take away the beauty of life.

-It will ultimately wipe out many other species of life.

- It will take away the beauty and uniqueness of our planet earth.

- Papers will become costly.

- In short, Life without trees is not life but lifelessness!

  Hope this helps u friend...