 Other factors include overgrazing by livestock, especially animals such as goats, cows, and over-harvesting of forest resources.Together these may lead to desertification and the loss of topsoil; without soil, forests cannot grow until the long process of soil creation has been completed - if erosion allows this.In some tropical areas, forest cover removal may result in a duricrust or duripan that effectively seal off the soil to water penetration and root growth.