Canterbury-Otago Tussock Grasslands
Bioregion: New Zealand (AU1)
Ecoregion Size (1000 ha):
States: New Zealand
This ecoregion lies in the rain shadow of the Southern Alps. Prior to clearing and fires brought by man, coastal broadleaf forests, kahikatea swamp forest (Dacrycarpus dacrydioides), and low conifer-dominated forest covered the land but over time transitioned to today’s tussock grasslands. Some of the driest inland areas near Otago are thought to have been treeless originally. Large flightless ratites (moa) were hunted to extinction long ago, but their heavy browsing on leaves is hypothesized to have driven a range of native plant defenses including leaves inside of thickets of spiny branches and plants and leaves mimicking unhealthy plants. Though controversial still, roughly 20% of the native flora is thought to display traits linked to defenses against ratite browsing.
Drier inland areas had low conifer-broadleaf forests with mountain toatoa (Phyllocladus alpinus), Hall's totara (Podocarpus hallii), broadleaf (Griselinia littoralis), and kanuka (Kunzea ericoides). Foothills were covered in beech forest (Nothofagus spp.). Lower plains had mixed beech-podocarp forest dominated by matai (Prumnoptitys taxifolia) and totara (Podocarpus totara). The short, drought-resistant tussock communities that replaced the lower forests are mainly hard tussock (Festuca novae-zelandiae), silver tussock (Poa cita), and Carex inopinata where not replaced by introduced pasture plants. At higher elevations one finds cushion plants, such as Chionohebe myosotioide, tall tussocks (Chionochloa spp.), and large herbs like the speargrass (Aciphylla subflabellata). The majority of low- and mid-altitude grasslands are now highly modified as a result of fires, weed invasion, overgrazing, irrigation, and rabbit plagues. Original beech forest remnants still occur in northern and southwestern parts of the ecoregion. Some extant, but threatened native plants include the shrub Hebe cupressoides, Hector’s tree daisy (Olearia hectori), and the Peraxilla mistletoes. Along braided rivers one finds cushion plants (Raoulia spp.), willowherbs (Epilobium spp.), Muehlenbeckia axillaries and encrusting lichens.
The braided river systems are the habitats of at least 26 waterbird species, such as black stilt (Himantopus novazelandiae). McCann's skink (Oligosoma maccanni) also lives in these braided rivers. Otago skink (Oligosoma otagense) and the grand skink (Oligosoma grande) are endemic to this ecoregion, but land modification has led to an approximate 90% decrease in their range. The unique Canterbury mudfish, an endemic, survives in mud in dry seasons. The region also has 120 endemic moth species.
Weeds and livestock browsing threaten plant communities. Intensive grazing, introduced weeds and pasture plants, and repeated fires are persistent threats to native species and habitats. Rock and Pillar, Lammermoor, Old Man, Old Woman, Pisa, and Remarkable Ranges constitute several protected areas totaling about 50 km2. The key conservation actions for the next decade are to: 1) protect and enhance wetlands and rivers, including weed control on braided rivers to provide favorable habitat for stilts and wrybill; 2) protect remnant native tussock grassland and beech forest from grazing, introduced browsers, and wildife; and 3) protect and effectively manage inland salt pans in Central Otago and their unusual native plant species.
- ECAN. 2008. A Biodiversity Strategy for the Canterbury Region 2008. Retrieved from https://www.ecan.govt.nz/your-region/plans-strategies-and-bylaws/canterbury-biodiversity-strategy/#:~:text=The%20Biodiversity%20Strategy%20for%20the,represented%20on%20the%20advisory%20group.
- New Zealand Department of Conservation. 1998. Otago Conservation Management Strategy. Otago Conservation Management Planning Series: 7. Otago Conservancy. Dunedin, New Zealand.
- Project River Recovery. Retrieved from https://www.doc.govt.nz/our-work/freshwater-restoration/project-river-recovery/