Question

Deforestation leads to _____.
A- Soil erosion and degradation of soil
B- Climate change and decrease in groundwater level
C- Reduction of forest products and loss of biodiversity
D- All of these

Answer 1

Hint:
-Forest litter allows replenishment of soil with nutrients.
-Water flows much quicker in places that are deforested, rather than a forest covered area.
-Forests are home to almost all kinds of living organisms on the planet.

Complete answer:
A. When the forest is thick, there is also a lot of plant litter in the area. It refers to the dead remains of the plant which cover the top layer of the soil. They provide protection to the surface soil from erosion. They also decompose and replenish the soil with nutrients. Hence, with deforestation there will be no such replenishment and the soil quality will degrade. Also the rate of soil erosion will increase to a significant amount.
B. Deforestation is one of the major causes of Global Warming. Deforestation has increased the amount of greenhouse gases by 20%. The most significant greenhouse gas, $CO_{2}$ is absorbed by plants. But deforestation leads to less number of plants and less absorption of $CO_{2}$. Therefore, it affects the climate of the Earth.
Due to deforestation, the water content in soil decreases. So does the groundwater level and the atmospheric water. Since transpiration does not occur due to lack of trees in a deforested area, that area does not receive a good amount of rain. Deforestation also causes flash floods and localized floods.
C. It leads to a loss of forest products and loss of biodiversity. It is a known cause for the extinction of thousands of species over the years. Forests are home to almost all kinds of plants and animals. Therefore, if trees are cut down it is going to reduce the number of trees and plants and subsequently, the number of animals living in that area.

Therefore , the correct answer is D

Note:
A lesser known consequence of deforestation is the spread of diseases from the deforested area.
As the forests are destroyed, many animals and insects come into places occupied by humans and bring with them certain diseases which humans were never exposed to before.
Some of the deforestation associated diseases are trypanosomia, leishmania, malaria, ebola etc.