New Guinea Highlands

Geology

This chain of mountains continues to rise (with corresponding quakes) as the Australian Plate collides with the plates to the northeast, marking the southern boundaries of the Maoke and Woodlark plates. The width of the mountain range varies considerably, with a central thin segment near the borders of the two nations.

The surface geology of the highlands is made up of metamorphic and intrusive igneous rocks. The metamorphic rocks were Cretaceous and Eocene ocean sediments that were uplifted and folded between the Eocene and early Miocene periods. There are also Pleistocene stratovolcanoes in the highlands, including Mount Hagen and Mount Giluwe.

History

The fertile Highlands have long been inhabited and artifacts uncovered in the Ivane Valley indicate that the Highlands were first settled about 50,000 years ago. The inhabitants were nomadic foragers but around 10,000 years ago began developing a fairly advanced agricultural society. Before the introduction of the sweet potato, the Highlands had distinct forms of division of labor. In the Eastern Highlands the economy was mixed, with men hunting and cultivating, and women gathering and tending crops. Populations were small, dispersed, and focused on immediate consumption. In the Western Highlands, women were focused on producing large amounts of taro, while men abandoned hunting and were instead focused on animal husbandry and trading. The introduction of the sweet potato had a significant impact on animal husbandry in the area. As it could be used as pig fodder without the need for cooking, societies that adopted this new staple food were able to rapidly amass pigs. These pigs were then traded with surrounding societies, becoming the centerpiece of early economies in the area.

The Highlands were not settled by the Western powers during the early colonial period and they were first visited by western zoologists and explorers, such as Mick Leahy, who opened the Wahgi Valley and Mount Hagen, and Richard Archbold in the 1930s. It was found that the highland valleys explored in the 1930s were inhabited by over a million people. During World War II, the eastern highlands saw the Kokoda Track campaign in which Australian and New Zealand soldiers, along with native guides who were pressed into service, fought and ultimately stopped the Japanese from advancing south towards Port Moresby and, ultimately, northern Queensland on the Australian mainland.

The culture of inter-tribal warfare and animosity between the neighboring tribes have long been present in the Highlands.

Ecology

The New Guinea Highlands are home to a great variety of Australasian plant and animal communities, distinct from the surrounding lowlands to the north and south of the central ranges and varying up and along the mountain ranges. The habitats of the mountains have been separated into two ecoregions, depending on their elevation, the tropical montane forests and alpine grasslands, but within these broad bands there is a variety of wildlife along the island as some of the mountains stand quite a distance from others with some species of plant or animal existing on only one or two mountains. Particular centres of plant diversity are the Star Mountains area of western Papua New Guinea near the Indonesian border including Telefomin and Strickland Gorge; the Hunstein Range; Mount Giluwe, a major birdwatching area for birds-of-paradise; the volcanic limestone Kubor Range; the Bismarck Range/Mount Wilhelm/Schrader Range/Mount Gahavisuka, of which Mount Wilhelm is particularly rich in endemic species; and finally the Crater Mountain and Mount Michael in the Eastern Highlands.

Central Range montane rain forests

The montane rain forests (from 1,000 to 3,000m) can be further categorised into three broad vegetation zones on the mountains, distinguished by elevation. The lower montane forests extend from 1,000 to 1,500 metres elevation. They are dominated by broadleaf evergreen trees, including Castanopsis acuminatissima, Lithocarpus spp., elaeocarps, and laurels. Coniferous Araucarias may form thick stands. The upper montane forests, which extend from 1,500 to 2,500 metres in elevation, are dominated by moss-covered Nothofagus. Finally, the high mountain forest extends from 2,500 to 3,000 metres in elevation. Conifers (Podocarpus, Dacrycarpus, Dacrydium, Papuacedrus, Araucaria, and Libocedrus) and broadleaf trees of the myrtle family (Myrtaceae) form a thin canopy, with a prominent understory.

The montane forests are home to a rich wildlife, a great deal of which is unique to these mountains including many plants, reptiles, and over 100 birds and animals. Of the 90 mammals found on the island, 44 are endemic, a very high proportion. The birds and animals include many Australasian species such as tree-kangaroos, bowerbirds, Australasian robins, honeyeaters, and birds of paradise. Four of the endemic mammals are critically endangered: the Bulmer's fruit bat, with only tiny communities remaining in the Papua New Guinea end of the island, and three rodents; a large Leptomys, the eastern shrew mouse, and the lesser small-toothed rat. There are 55 bird species endemic to the mountains from a total of 348 birds found here. There are several endemic butterflies, particularly in the Weyland Mountains and the Wahgi Valley.

Apart from the cultivated valleys, the montane forests are largely intact, although the logging industry is a constant threat as more and more access to the mountains is achieved by road building. 20% of this ecoregion is contained within protected areas, mostly in the Indonesian half of the island, including the largest protected area in Southeast Asia, the huge Lorentz National Park in the highlands, a section of which is a montane forest ecosystem.

Central Range sub-alpine grasslands

Above 3,000 metres elevation, the high mountain forest transitions to remote sub-alpine habitats including alpine meadows, conifer forest, tree-fern (Cyathea) grasslands, bogs, and shrubby heaths of Rhododendron, Vaccinium, Coprosma, Rapanea, and Saurauia all quite different from the tropical rain forest that covers most of New Guinea.

The alpine habitat above 4,000 metres consists of compact rosette plants and cushion herbs, such as Ranunculus, Potentilla, Gentiana, and Epilobium, grasses (Poa and Deschampsia), bryophytes, and lichens.

While there are several endemic plants there are few animals on the higher slopes, with only nine mammals found here: four rodents, two bats, a cuscus possum, an antechinus, and Doria's tree-kangaroo (Dendrolagus dorianus). Four of these are endemic: the small marsupial black-tailed antechinus (Murexechinus melanurus), western shrew mouse, glacier rat, and alpine woolly rat. There are nearly 100 birds of which 28 are considered endemic or nearly so, including the vulnerable long-bearded honeyeater (Melionyx princeps), ribbon-tailed astrapia (Astrapia mayeri), and Macgregor's giant honeyeater, which although endangered generally is a cultural icon of the Ketengban people of the Star Mountains and therefore protected in some areas.

Almost half of these remote grasslands are protected in national parks and they are in good condition although in recent times more people are accessing the highlands as visitors or through involvement in mining.

Protected areas

There are several protected areas in the highlands. They include:

• Enarotali Nature Reserve
• Jimi (Ruti) Valley National Park
• Lake Kutubu Wildlife Management Area
• Lorentz National Park
• Memberamo Foja Wildlife Reserve
• Mount Wilhelm National Park
• Weyland Mountains (Pegunungan Wayland) Nature Reserve