Original sentence: It protects a still largely natural example of a high-altitude lake, most of which have been cleared or severely modified in the region.It thus serves as a refuge for numerous species of birds, mammals, amphibians and reptiles.The Little Llangothlin Nature Reserve has some of the last high-altitude freshwater lagoons on basalt soil on the New England Tableland.The lagoon fills a natural depression in the tableland landscape; a former agricultural drainage ditch has been filled in to restore its original water depth of about  when full.The wetlands of the reserve form a drought refuge for many kinds of waterbirds as well as supporting several species of frogs and reptiles
Edited sentence: It protects a still largely natural example of a high altitude lake, most of which have been cleared or severely modified in the region.It thus serves as a vital refuge for numerous species of birds, mammals, amphibians and reptiles.The Little Llangothlin Nature Reserve is an important site because it has some of the last high altitude freshwater lagoons on basalt soil on the New England Tableland.The lagoon fills a natural depression in the tableland landscape; a former agricultural drainage ditch has been filled in to restore it’s original water depth of about  when full.The wetlands of the reserve form an important drought refuge for many kinds of waterbirds as well as supporting several species of frogs and reptiles