It is most probably due to its great variety of habitats that the Leuser Ecosystem is capable of supporting such a rich biological diversity - considered to be among the richest in South East Asia. Most species are found in the lowland forests - which are being cleared almost everywhere else in Sumatra. These forests are not only the habitat of the Sumatran Elephant ( elephas maximus ), Orangutan ( pongo pygmaeus ), Sumatran Tiger ( panthera tigris sumatraensis ), Sumatran Rhinoceros ( dicherorinus sumatraensis ) and some spectacular bird species such as the Argus Pheasant, but are home to the magnificent dipterocarp trees that are so sought after by the timber industry, and, in some cases, are now becoming rare.