Introduction

The Central Range sub-alpine grasslands are a unique example of alpine shrublands surrounding the highest peaks (up to 4,884 meters) in Australasia. These fragile environments are fairly well protected by a combination of formal protection and remoteness.

Location and General Description

Papua New Guinea. (Photograph by John Morrison)

This ecoregion is made up of scattered alpine meadow habitats above 3,000 meters (m) along the Central Cordillera in Irian Jaya, Indonesia and Papua New Guinea (PNG). The Central Cordillera is composed of a series of mountain ranges, which are broadly grouped into the Snow Mountains in Irian Jaya, the Star Mountains in Irian Jaya and PNG, and the Central and Eastern Highlands PNG. Although most of New Guinea has a tropical wet climate, in the case of this ecoregion it is modified by extreme altitude. Another classification system puts this ecoregion in a humid upper montane climate. The surface geology of the Central Cordillera is composed of metamorphic and intrusive igneous rocks, along with some sedimentary formations.

The vegetation of the ecoregion consists of alpine meadow, montane, and upper montane tropical evergreen forest. Vegetation in the Central Ranges varies with elevation, local climate, aspect, and substrate. Upper montane forest consists of conifers (Podocarpus, Dacrycarpus, Dacridium, Papuacedrus, Araucaria, and Libocedrus) and Myrtacae, with a thin canopy and prominent understory. Above the montane forest, at approximately 3,000 m, the vegetation abruptly changes, and the high plateau areas of the cordillera are interspersed with tree fern (Cyathea) savannas, bogs, and grasslands. Immediately below the alpine zone, the vegetation typically is low shrubs and Deschampsia tussock grasslands. Heaths of Rhododendron, Vaccinium, Coprosma, Rapanea, and Saurauia form the limit of sub-alpine forest. The alpine habitat above 4,000 m consists of compact herbs such as Ranuculus, Potentilla, Gentiana, and Epilobium, the grasses Poa and Deschampsia, and bryophytes and lichens. Rosette and cushion herbs, mosses, lichens, and low ferns become progressively more abundant with altitude and replace grasses above 4,300 m. The highest areas are capped by snow and ice fields.

Biodiversity Features

With the exception of plant endemism, overall richness and endemism of this ecoregion are low when compared with those of other ecoregions in Indo-Malaysia.

This extreme environment is inhabited by only nine mammals, consisting of four murid rodents, two microchiropteran bats, and three marsupials: a tree kangaroo, a cuscus, and an antechinus. Of these mammals, four are endemic or near endemic (Table 1). The western shrew mouse (Pseudohydromys occidentalis) and Doria's tree-kangaroo (Dendrolagus dorianus) are considered vulnerable.

Eighty-four bird species inhabit this ecoregion, of which an amazing twenty-eight species are endemic or near-endemic (Table 2). The Central Range sub-alpine grasslands constitute the upper elevations of the Central Papuan Mountains Endemic Bird Area (EBA), which it shares with the Central Range montane rain forests ecoregion. Although the entire EBA contains fifty-four restricted-range species, only twenty-four of these range into the sub-alpine grasslands. The long-bearded honeyeater (Melidectes princeps), MacGregor's bird-of-paradise (Macgregoria pulchra), the ribbon-tailed astrapia (Astrapia mayeri) are considered vulnerable.

Five Centres of Plant Diversity (CPD) are shared between this ecoregion and the adjacent Central Range montane rain forests ecoregion. The Star Mountains-Telefomin-Tifalmin-Strickland Gorge CPD in PNG contains very rich (more than 3,000 vascular plant species) montane and high-altitude vegetation. Alpine communities are found on the summit of Mt. Giluwe, in the Mt. Giluwe-Tari Gap-Doma Peaks CPD. The poorly known Kubor Ranges in PNG contain extensive areas of high-altitude vegetation, and many endemics are likely to exist on the limestone and volcanic ash. The Bismarck Falls-Mt. Wilhelm-Mt. Otto-Schrader Range-Mt. Hellwig-Gahavisuka CPD has a wide variety of vegetation types and contains more than 5,000 vascular plant species. There are numerous endemics already known from the sub-alpine and alpine areas of Mt. Wilhelm, the highest point in PNG.

Current Status

The eleven protected areas that extend into this small ecoregion cover 7,290 square kilometers (km²), representing more than 47 percent of the ecoregion area (Table 3). A gap analysis, based on detailed vegetation and habitat type mapping, has never been performed to determine whether the existing protected area network adequately covers all habitats with protected areas that are large enough to maintain all critical ecological processes.

Types and Severity of Threats

Mining exploration and access afforded by mining operations have become significant sources of threats to this sensitive alpine habitat. Visitation has also increased the level of pollution and litter in the area.

Justification of Ecoregion Delineation

Mt. Wilhelm, Papua New Guinea. (Photograph by John Dumbacher)

Using Whitmore's map of the vegetation of Malesia and MacKinnon's reconstruction of the original vegetation, we delineated the large areas of distinct habitat types as ecoregions. The montane evergreen moist forests along the Central Cordillera, including the Snow Mountains, Star Mountains, Central Highlands, and Eastern Highlands, were placed in the Central Range montane rain forests. This ecoregion roughly corresponds to MacKinnon's subunits P3g, P3h, and P3i. The moist forests in the southeastern peninsula were distinguished as the Southeastern Papuan rain forests. This ecoregion consists mostly of montane forests but also includes some lowland forests along the coasts and is roughly equivalent to MacKinnon's biounit P3n. We used the 1,000-m contour from a digital elevation model (DEM) to define the montane-lowland transition. All along the Central Cordillera and in the Huon Peninsula, we separated the alpine habitat into a distinct (Central Range sub-alpine grasslands) ecoregion. Udvardy placed these ecoregions in the Papuan biogeographic province of the Oceanian Realm.

Additional Information on this Ecoregion

• For a shorter summary of this entry, see the WWF WildWorld profile of this ecoregion.
• To see the species that live in this ecoregion, including images and threat levels, see the WWF Wildfinder description of this ecoregion.
• World Wildlife Fund Homepage