Why is soil erosion relatively less in dense forests as compared to barren, open fields?

In dense forests, the tree cover (canopy) prevents rainwater from directly falling on the forest floor. The canopy layer of the forest intercepts the flow of raindrops so that rainwater falls on the leaves of trees and then drips slowly onto the forest floor. Thus, forests allow rainwater to seep.

The roots of the vegetation bind the soil particles and hold them firmly which protects the topsoil and prevents it from getting eroded by wind or water. 

In barren, open fields the soil is exposed to the wind and falling rain. The soil particles become loose and easily get carried away by blowing wind or flow of water. Therefore, soil erosion is relatively less in dense forests as compared to open barren fields.