What deforestation causes?
Deforestation can cause animal habitat destruction, takes away oxygen, destroys liveleyhood for native people, creates soil erosions, raises temperature swings and turns forest's into deserts. As you see, all the above causes were bad or could harm us.
Habitat destruction is caused because there are lots of animals that live in the forest's and when all the trees are cut down in that area and all the animals don't have a place to live now. Did you know that every 30 minutes, 1 species become extinct?
Soil erosions are where the soil has no water. This makes a higher chance of landslides and other natural disasters. This is caused because there are no trees to absorb water and block the sunlight.
Oxygen is air that flows around you and you breathe into. If we do not have enough oxygen, we would die because oxygen makes us live and without it, there would be too much co2.
Temperature swings are where the temperature changes from day to night. If there are no trees, there are no trees to absorb heat at day and release it at night.