Southland temperate forests
The Southland temperate forests ecoregion covers the southeastern tip of New Zealand's South Island; however, much of the Southland region is modified and large areas are intensively farmed. Nevertheless, there are still significant coastal wetlands and upland areas of beech forest and tussock grasslands. The Eyre Mountains support distinctive local endemic plant species and the Catlins National Park contains an outstanding range of habitats, ranging from coastal habitat to alpine bogs.
The region entered a biodiversity downturn with advent of the Maori peoples, who significantly deforested this ecoregion; moreover, the destruction expanded with advent of Europeans and introduction of lanrge scale domesticated livestock grazing. A number of protected areas are found in the region, but lowland and grassland communities are underrepresented in conservation reserves; moreover, logging, clearing for development, and introduced alien species animals are biodiversity threats.
Location and General Description
Located at the southernmost extreme end of South Island, Southland consists of coastal lowlands separated from dry central plains by the hills of the Hokonui Syncline. Rainfall on the damp coastal lowlands ranges between 900 millimetres (mm) to 1600 mm per year, while the relatively dry central plains receive annual rainfall from 700 mm to 900 mm. Further north there a band of high, forested mountains run along the boundary with Otago. The Te Anau Basin in the northeastern edge of the region is separated from the other lowland areas by the rugged Takatimu Range which has extensive scree features not seen elsewhere in the region. To the southeast lies the rolling hill country of the Catlins where a lush and diverse forest can grow right down to the coast. The rest of the southern coast is characterized by dunes with large open bays and estuaries separated by rocky outcrops. When the glaciers retreated from the uplands and the Te Anau basin (10,000 years ago) near the latter part of the fifth ice age , the lowlands became covered with outwash gravels and mantled with loess but the underlying sedimentary rocks (lignite, limestone, sandstone, and mudstone) are much older and their origin more complex. Greywacke and argillite extends across the north of the region in a broad belt below the schists of Otago but there are also basaltic tuffs, diorite, gabbro, and a range of ultramafic rocks such as serpentine and peridotite.
Forests recolonized Southland after the most recent ice age glacial advance and remained the dominant vegetation cover until about 1000 years ago. Silver beech (Nothofagus menziesii) was present in higher altitudes to the west with red beech (Nothofagus fusca) in the northern mountains. In the lowland areas podocarps and hardwoods were predominant with kahikatea (Dacrycarpus dacrydioides) growing in swampy areas and rimu (Dacrydium cupressinum) on drier sites. Southern rata (Metrosideros umbellata) and kamahi (Weinmannia racemosa) were present in the central hill country and in the Catlins.
Charcoal evidence shows fires began in the region about 2500 years ago and greatly increased in frequency after the arrival of Maori, since the Maori people used fire to drive game from the forests for mass killing. These fires led to the loss of large areas of forest and their replacement by tussock grasslands: snow tussocks (primarily Chionochloa spp.) above the treeline and red tussock (Chionochloa rubra) spread over an estimated 45 percent of the region. By the time Europeans arrived some forest regeneration had started but most of this land was again cleared for farms and other developments. Livestock had a major impact on the tussock lands and exotic pasture grasses took over areas once dominated by red tussocks. Europeans also drained many of the wetland areas in the lowlands. Some forest remnants have been preserved, mainly in the Livingston, Snowdon, and Eyre Mountains, the Catlins area, the Hokonui Hills, and around Waitutu to the south. However, little lowland swamp survives.
The Catlins Forest Park (420 square kilometres) contains a rich and diverse flora and a wide range of habitats, from the alpine bogs found on the Ajax Plateau to salt marshes and rocky coastal cliffs. In places unbroken sequences of native vegetation run from the coast to the subalpine zone. It is also the only large area of the eastern coast of New Zealand retaining a predominantly natural forest cover. Catlins Forest Park contains rimu-dominant podocarp forest, as well as New Zealand's southernmost stand of silver beech (Nothofagus menziesii). An endemic daisy, Celmisia lindsayi, is found on the coastal cliffs. It is home to several endangered birds, most notably the world's rarest penguin, the vulnerable Yellow-eyed penguin (Megadyptes antipodes). Mohua or yellowheads (Mohoua ochrocephala VU) have small South Island populations that are generally decreasing, but they have started to recover here following intensive stoat control (Mustela erminea). The Catlins Forest Park coastline is the only place where elephant seals (Mirounga leonina), New Zealand fur seals (Arctocephalus forsteri) and the New Zealand sea lion (Phocarctos hookeri VU) all co-exist. New Zealand sea lions have only resumed breeding on the mainland since 1992, and now breed here and along the Otago coastline.
Subalpine and alpine vegetation communities in the Eyre Mountains are in good condition and have high levels of endemism and a number of species that are considered priorities for conservation efforts. There are large areas of snow tussock grassland and significant tracts of unmodified indigenous beech forest. The only population of rock wrens (Xenicus gilviventris) known to exist outside the Southern Alps is found here. Endemic alpine species include Carex uncifoli, Hebe biggarii, Celmisia thomsonii, and Aciphylla spedenii. One of the Department of Conservation's priority species for conservation protection, the South Island tree daisy (Olearia hectori EN), is found in shrub lands outside existing protected areas.
Tussock grasslands are important habitat for birds of the open country like Australasian harriers (Circus approximans) and South Island fernbirds (Bowdleria punctata punctata). Tussock dependent reptiles include the green skink (Oligosoma chloronoton), found only in Southland, Otago, and Stewart Island, and the Otago skink (Leiolopisma otagense), which is found only in Otago and Southland. The small remaining areas of coastal tussocks, such as Poa astonii, provide habitat for several species with limited distributions including an endemic chafer beetle, Prodontria praelatella.
The Southland coast and associated wetlands support a wide range of invertebrates and wading birds. Dunes and dune lakes are still found in good condition in Southland. Although they have been extensively modified throughout New Zealand, here they may extend up to ten km inland. The Waituna Lagoon is notable for its abundant bird life and the extensive marshes along the lagoon. The only mainland populations of one of New Zealand's rarest plants, Gunnera hamiltonii, are found in stable dune systems on the coast near Invercargill. The other small populations of this ground-hugging herb are found on Rakiura Island.
Public conservation lands administered by the Department of Conservation include large areas of the forested Takitimu, Snowdon, Eyre, and Blue Mountains, the forests of Western Southland, Rowallan, Longwoods, and Dean, and the Pembroke and Glaisnock Wilderness Areas. Some protected areas were conserved because land development was not economical, but other areas were logged prior to their protection.
Lowland shrub communities, coastal dune ecosystems, and tussock grasslands, particularly red tussocks are poorly protected. For example, less than 20 km2 of lowland red tussocks are protected. There are a few notable exceptions, such as the Waituna Lagoon, which has been designated a Wetland of International Importance under the United Nations Ramsar Convention. The area covered by the Ramsar listing will be extended by 200 km2 to include the three major estuaries, Toi Toi, Awarua Bay, and the New River. This expansion will include slightly more than 100 km2 of the Awarua peat complex and areas of cushion bog which are usually only found in subalpine regions.
Types and Severity of Threats
Over the last 100 years a number of species have disappeared from Southland. Extirpated species include birds such as the South Island subspecies of the endangered kokako (Callaeas cinerea cinerea) and the extinct piopio (Turnagra capensis), the grayling fish (Prototroctes oxyrhynchus), and plants like Stellaria elantinoides. Remaining populations of many species are still threatened by predation from introduced species and environmentally harmful activities including the continued drainage of wetlands, burning and grazing of tussock grasslands, and clearance of indigenous vegetation for land development.
The most significant threats facing the remaining unprotected land in Southland, particularly in lowland areas and riparian forests, is grazing, logging and burning for land development or timber. Waterways and native fish species are also threatened by the increasing trend of converting farms to dairy production, which tends to be more intensive and have higher environmental impacts (e.g., increased nutrient run-off and erosion).
Particularly significant threats exist for the coastal forests which are critical breeding habitat for the Yellow-eyed penguin. This penguin species requires upland breeding locations, unlike some other penguins whose nests and burrows are found rather near the shoreline. Deforestation for expanded grazing and urban development in the coastal zone are the chief drivers of this threat. Terrestrial breeding habitat up to one km inland from the coast is the limiting factor for survival of this penguin species. The Southland temperate forests represent the chief remaining breeding habitat for this bird. There are some ongoing efforts at coastal reforestation to enhance and expand habitat for this penguin, notably on the southern edge of the Otago Peninsula.
Small and fragmented areas of natural habitat, surrounded by agricultural land, are prone to pest invasion. Fencing of these areas is a priority if natural values have been maintained. For larger blocks of protected forests, the main management issue is pest control. Possums (Vespula vulgaris), red deer (Cervus elaphus), goats (Capra hircus), and pigs (Sus scrofa) are found throughout Southland's forests along with the ubiquitous rats (Rattus rattus and R. norvegicus) and three mustelids: stoats (Mustela erminea), ferrets (M. putorius), and weasels (M. nivalis).
Tussock grassland species are threatened by invasion and suppression by weed species like broom (Cytisus scoparius), Corsican pine (Pinus nigra laricio), and Douglas fir (Pseudotsuga menziesi). Marram (Ammophilia arenaria) is a serious weed problem on the coastal dunes and Canadian pondweed (Elodea canadensis) is problematic in freshwater ecosystems. Willows (Salix cinerea and S. fragilis) dominate riparian and wetland margins, causing silt build up and shrinking natural habitats.
Justification of Ecoregion Delineation
The Southland temperate forests ecoregion largely conforms to Wardle's Southland Botanical Province. However, the 'Mavora' Ecological Region was excluded from the Southland temperate forests because the Mavora Ecological Region contains high percentages of grassland vegetation.
- For a shorter summary of this entry, see the WWF WildWorld profile of this ecoregion.
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- Department of Conservation. 1987. New Zealand topographical map: Ecological regions and districts of New Zealand. Map (1:500,000). Departments of Lands and Survey, Wellington, New Zealand.
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- Department of Conservation. 2000. Conservation Management Strategy for Mainland Southland/West Otago 1998 – 2008. Southland Conservancy Conservation Management Planning Series No 9. Invercargill.
- New Zealand Department of Conservation - Te Papa Atawhai.
- Hilton-Taylor, C. 2000. The 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, United Kingdom. ISBN: 2831705657
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