To facilitate more effective and economical grazing use, structural facilities, commonly called range improvements, are installed on the allotments. Some of these improvements, such as corrals and other exclosures, are needed to facilitate the handling of livestock; others, such as wells and spring developments, are to provide water for the livestock and wildlife. Other improvements, such as fences or strategically located watering or salting facilities, are needed for controlling livestock for effective grazing management, by helping disperse the grazing throughout the allotment (this can improve wildlife habitat too). Traditionally, these types of facilities have been installed as cooperative ventures between the permitee/lessee and the BLM. Many improvements have been installed and are maintained soley by the rancher as permitted by BLM. Many facilities are also located on privately-owned or non-Federal lands within allotment boundaries. In the past, there have been a few vegetation conversion projects on some allotments. Examples include re-seeding projects using either exotic or native species, and brush control projects using either mechanical or chemical methods or prescribed fire. There has been mixed success with all of these projects in meeting expectations.