This ecoregion is a large area of dry grassy plains between the east coast and the Southern Alps / Kā Tiritiri o te Moana that form the spine of South Island, in the regions of Canterbury and Otago.

Some upland areas have a cover of Chionochloa tussocks plus heath of Chionohebe and spiky Aciphylla plus some threatened plant species including the shrub Hebe cupressoides, a daisy (Olearia hectori), and some Peraxilla mistletoes.

The Hinewai Reserve on the Banks Peninsula preserves enclaves old-growth and second-growth forest, mostly of red beech (Nothofagus fusca), with evergreen broadleaf shrubs and low trees including kānuka (Kunzea ericoides), māhoe (Melicytus spp.

The Canterbury riverbeds are an important habitat for invertebrates such as McCann's skink (Oligosoma maccanni), and especially birds such as the very rare black stilt (Himantopus novazelandiae) which remains only in wetlands of the Waitaki River system.

Original wildlife has also been damaged by introduced plants including lodgepole pine, broom, and sweet briar, while hawkweed and other weeds can more easily establish themselves when land is overgrazed.

Introduced species of animals that cause damage include possums, goats, red-necked wallaby, and red deer along with predators such as cats, rats, stoats and ferrets.