Leith Saddle is a saddle between the sources of the Water of Leith and the Waitati River, approximately halfway between Dunedin's northern suburb of Pine Hill and the outlying settlement of Waitati. The saddle is a strategic point where the Dunedin Northern Motorway, part of State Highway 1 traverses a fragile alpine forest. Proposed road works to straighten a dangerous corner here conflict with conservation values. Water supply pipelines, and popular tramping and cycling routes also converge at the saddle.
A mountain pass is a navigable route through a mountain range or over a ridge. Since many of the world's mountain ranges have presented formidable barriers to travel, passes have played a key role in trade, war, and both human and animal migration throughout Earth's history. At lower elevations it may be called a hill pass. The highest vehicle-accessible pass in the world appears to be Mana Pass, located in the Himalayas on the border between India and Tibet, China.
The Waitati River is a river in New Zealand, flowing into the Pacific Ocean at Blueskin Bay, north of Dunedin. The Dunedin Northern Motorway follows the valley of the Waitati between the Leith Saddle and Waitati.
Dunedin is the second-largest city in the South Island of New Zealand, and the principal city of the Otago region. Its name comes from Dùn Èideann, the Scottish Gaelic name for Edinburgh, the capital of Scotland.
The Water of Leith's source is 100 metres to the south of Leith Saddle, at a height of 380 metres above sea level. [1]
The Leith Saddle Track is a 3.5 hour climb through native cloud forest to Swampy Spur and Swampy Summit with links to other walkways in the Silverpeaks and Dunedin's hills. [2]
A cloud forest, also called a water forest and primas forest, is a generally tropical or subtropical, evergreen, montane, moist forest characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level, formally described in the International Cloud Atlas (2017) as silvagenitus. Cloud forests often exhibit an abundance of mosses covering the ground and vegetation, in which case they are also referred to as mossy forests. Mossy forests usually develop on the saddles of mountains, where moisture introduced by settling clouds is more effectively retained.
Swampy Summit is a prominent hill 12 kilometres (7.5 mi) to the north of Dunedin, New Zealand. It reaches a height of 739 metres (2,425 ft).
The Silverpeaks is an area of rough forest and tussock and scrub covered hill country inland and to the northwest of Dunedin, New Zealand. The area is largely uninhabited; the main indication of human activity is the Taieri Gorge Railway, which preserves the route of the former Otago Central Railway that runs along the steep-sided valley of the Taieri River. Much of the area lies within the Silverpeaks Scenic Reserve.
The Dunedin Northern Motorway has an at-grade intersection at the Leith Saddle summit with Leith Valley Road and Waitati Valley Road. Both have low motor vehicle volumes and have metalled surfaces, making them attractive to cyclists. [3]
Transit New Zealand signalled a long term intention in 2004 to realign SH1 in the vicinity of Leith Saddle; construction would require removal of some old-growth forest. [4]
Transit New Zealand, which existed from 1989 to 2008, was the New Zealand Crown entity responsible for operating and planning the New Zealand state highway network. It also concerned itself with developments close to state highways, as it considered the potential additional traffic that these would create, and it was responsible for state highway landscaping.
An old-growth forest — also termed primary forest or late seral forest — is a forest that has attained great age without significant disturbance and thereby exhibits unique ecological features and might be classified as a climax community. Old-growth features include diverse tree-related structures that provide diverse wildlife habitat that increases the biodiversity of the forested ecosystem. The concept of diverse tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters, and diverse tree species and classes and sizes of woody debris.
The forest here features a species of Libocedrus, variously called Pahautea, Kaikawaka or New Zealand cedar, Libocedrus bidwillii , which is unusual in this region of New Zealand. [5]
Libocedrus is a genus of five species of coniferous trees in the cypress family Cupressaceae, native to New Zealand and New Caledonia. The genus is closely related to the South American genera Pilgerodendron and Austrocedrus, and the New Guinean genus Papuacedrus, both of which are included within Libocedrus by some botanists. These genera are rather similar to the Northern Hemisphere genera Calocedrus and Thuja: in earlier days, what is now Calocedrus was sometimes included in Libocedrus. They are much less closely related, as recently confirmed. The generic name means "teardrop cedar", apparently referring to drops of resin.
Libocedrus bidwillii variously called pāhautea, kaikawaka or New Zealand cedar is a species of Libocedrus, endemic to New Zealand in both the North and South Islands; in the North Island, it occurs from Te Aroha southward. It grows at 250–1,200 m altitude in temperate rainforests.
Transit New Zealand stated in 2004 that Leith Saddle has 250% more accidents than average for the New Zealand state highway network and that the accident rate increased by 50% in the ten years to 2004. [4] They said realignment here would reduce traffic delays, fuel use, crashes, and emissions of carbon dioxide and carbon monoxide. [4]
A contour pipeline running southbound over the saddle from several tributaries of the Waitati River feeds two of Dunedin's water supply reservoirs in Leith Valley: Ross Creek Reservoir and Sullivans Dam[ citation needed ]. Treated, fluoridated water is transmitted northwards from Dunedin's municipal water system via a new pipeline to the rural settlements of Waitati, Warrington and Seacliff. [6]
