Deforestation is the process of cutting down trees and clearing forests or woodlands, typically to make way for agricultural or urban development. This process has a significant impact on the environment and can result in the extinction of many species. The following are the reasons why deforestation is the main reason for species extinction:

1. Loss of habitat: Deforestation leads to the destruction of natural habitats of many species. Trees provide homes for animals, birds, and insects. When these habitats are destroyed, the animals are forced to migrate, which can lead to the extinction of the species.

2. Fragmentation of ecosystems: Deforestation fragments ecosystems, creating isolated pockets of habitat that are too small to sustain a viable population of many species. As a result, many species become extinct due to the lack of genetic diversity and the inability to find mates.

3. Climate change: Trees absorb carbon dioxide from the atmosphere and release oxygen. The destruction of forests leads to an increase in carbon dioxide levels, which contributes to climate change. Climate change can cause the extinction of many species that cannot adapt to the changing environment.

4. Hunting and poaching: Deforestation also leads to an increase in hunting and poaching activities, as many species are displaced from their natural habitats. This further increases the risk of extinction for many species.

In conclusion, deforestation is the main reason for species extinction as it leads to the loss of habitat, fragmentation of ecosystems, climate change, and an increase in hunting and poaching activities. It is, therefore, essential to implement measures to protect forests and prevent their destruction to conserve biodiversity and prevent the extinction of many species.