Think about soil for a second. The part you're able to grab from the ground is called topsoil, the delicate top layer of soil that is also the most fertile part of the entire ground's ecosystem.
Because it is delicate, topsoil can easily be blown away by wind or washed away by rain, resulting in soil erosion, the direct cause of dying land, flooding, and mudslides.
When trees are introduced as a way of preventing erosion, roots grow deep to hold the soil in place and prevent runoff while the tree’s branches and leaves become natural wind barriers. The wind goes directly over the tall trees and not only slows down the wind’s speed but also protects the soil directly underneath.
Trees also reintroduce nutrients to the topsoil.
| CLICK to learn how how tree roots build soil (6:57min)