Fact 1: Erosion of soil has a negative impact on the environment.

Fact 2: Forests provide a clean and comfortable environment.

Given the two facts above, answer the question "Erosion of soil has what impact on a forest?" with the following options: 
- mechanical
 - negative
 - helpful
 - wind
 - healthy
 - forces
 - positive
 - flooding


 

  negative       