Tree planting requirements on private urban land usually form part of development approval. These are often included as a condition of permission to remove a regulated tree or as part of the approved landscaping of a new development. Tree planting may also be mandated through sustainability requirements in developments, where tree planting is one of several listed sustainability options. Tree planting conditions normally specify the location and size of the new tree, and may include species selection and a provision to replant the tree if it dies. Energy efficiency is the main site-scale policy driver for tree planting requirements. Drivers at the neighbourhood-scale include urban heat island mitigation and biodiversity support. Water efficiency is often a factor at the regional scale. The larger scale drivers are usually considered in urban forest strategies for public land, but are not often part of the required considerations for mandatory private urban tree planting. Nevertheless, courts are tending to enforce developer consideration of tree planting early in the site design process, due to its significance for all of these reasons. Key problems with mandatory tree planting are tree morbidity rates and developer non-compliance.