Deforestation is also the reason for loss of a natural habitat, with large numbers of trees being cut down for residential and commercial use. Urban growth has become a problem for forests and agriculture, the expansion of structures prevents natural resources from producing in their environment. In order to prevent the loss of wildlife the forests must maintain a stable climate and the land must remain unaffected by development. Furthermore, forests can be sustained by different forest management techniques such as reforestation and preservation. Reforestation is a reactive approach designed to replant trees that were previously logged within the forest boundary in attempts to re-stabilize this ecosystem. Preservation on the other hand is a proactive idea that promotes the concept of leaving the forest as is, without using this area for its ecosystem goods and services. Both of these methods to mitigate deforestation are being used throughout the world.