These managed ecosystems are derived from a range of other ecosystems (mostly from T1 - T4, a few from T5) by the removal or modification of woody plant components. The remaining vegetation includes both local indigenous species and introduced species, providing habitat for a mixed indigenous and non-indigenous fauna. They are used mainly for livestock grazing, which is essential to maintaining the structure of the system. Unlike sown pastures, inputs of water and nutrients are limited. Although structurally simpler than the systems from which they were derived, they often harbour an appreciable diversity of native organisms.