Large scale deforestation has resulted in many problems for mankind.
Increase in carbon dioxide, temperature and pollution levels on the earth, resulting in global warming.
Decrease in the oxygen level.
Cutting down of trees on large scale has resulted in depletion of water vapour in the atmosphere which has in turn affected cloud formation, thus, resulting in less rainfall. This can even cause droughts.
The decrease in rainfall is leading to desertification, as trees and plants die. Fewer trees result in more soil erosion. The top fertile soil is carried away, exposing the lower, hard and rocky layers which is less fertile. Over a period of time, fertile land gets converted into deserts, this is called desertification.
Deforestation decreases the water holding capacity of soil and decreases the infiltration rate of water into the ground.
Animals become homeless.