Discovery and description of the megadiverse flora of Papua New Guinea

Papua New Guinea (PNG) is considered one of the most species rich areas in the world, hosting about 6% of the world’s flora, and high levels of species endemism. However, there remains considerable speculation as to the size of the vascular flora, with estimates currently ranging from 11,000 to 25,000 species. The general consensus among authorities is that no plant family in PNG has been adequately inventoried nor studied. Such uncertainty in the knowledge of the taxonomy and extent of botanical diversity of the region hampers the prediction of the effects of anthropogenic actions, such as forestry and climate change, and development of conservation plans. Many more species may be threatened with extinction than the 1% currently listed by the IUCN, particularly as forest is currently being removed or degraded at the rate of 1.4% per year.

Number of described Herps over time

Despite species richness in many plant groups, New Guinea remains one of the most poorly-collected regions of Melanesia for the vascular flora. Average collection density (number of specimens per unit area) for PNG remains low at ~26 specimens per 100 km2, but with a maximum at ~770 per 100 km2. The minimum number for adequate floristic inventory is considered to be 50 collections per 100 km2 (red and green grid squares in the image above). Only 15% of the country meets or exceeds this minimum based on our analysis of the number of collections per quarter-degree grid cell. The areas with highest collecting density tend to be in road-accessible areas, along major rivers or the seacoast, subalpine and alpine areas on several massifs, and regions around large communities (e.g., Port Moresby, Lae).


The goals of this NSF-funded project were to:

The Papuan Region

New Guinea and adjacent islands are beset with confusing terminology. We refer to New Guinea as the entire island, including small, biogeographically associated satellite islands. The western half of New Guinea is politically part of Indonesia and is currently divided into Papua and West Irian Jaya provinces but was previously known as Irian Jaya and, prior to that, was Dutch New Guinea. The eastern half of New Guinea is occupied by the sovereign nation of Papua New Guinea, which also includes within its eastern boundaries the Admiralty and Bismarck Archipelagos and Bougainville and Buka islands. These latter two islands, together with a string of high islands and atolls to the SE, comprise the Solomon Islands, which, except for Bougainville and Buka, are politically part of the sovereign nation of the Solomon Islands. The entire area - New Guinea, the Admiralty and Bismarck Archipelagos and the Solomon Islands - is generally called the Papuan region.

Map of the Indo Pacific Region

The island of New Guinea is often likened to the shape of a bird, with the head consisting of the Vogelkop Peninsula in the far Northwest and the Southeastern Peninsula comprising the tail. A mountain axis runs the length of the island from the northwest to the southeast and divides the island into northern and southern versants. To the north of this Central Dividing Range lies a series of smaller ranges referred to as the northern coastal ranges. These extend from the Vogelkop Peninsula in West Papua Province, Indonesia, to the Huon Peninsula in Morobe Province, Papua New Guinea.

The geological history of the Papuan region is complex, which makes it of great interest for evolutionary studies. The southern half of New Guinea is the northernmost extension of the Australian Craton. Onto this continental margin two separate offshore island arc systems have been sutured by the collision of the Australian and Pacific plates. Approximately 45-50 million years ago, the Papuan Arc system accreted to the northern margin of the Australian Craton, creating what is now the Central Dividing Range. Within the past 10 million years, a second arc system, the Solomons Arc, has collided with New Guinea with a clockwise rotational motion, creating the series of northern coastal ranges. The offshore Bismarck and Solomon island groups are part of this same colliding arc system and are expected to dock with New Guinea over the course of the next several million years. The Southeastern Peninsula is a composite of geological terranes sutured together over a period of several million years and this landmass connected with the main mass of New Guinea approximately 30 million years ago.

New Guinea topography

This geological history has produced the worlds largest (~890,000 km²) and highest (5,030 m) tropical island, which includes permanent glaciers within 20 km of typical wet tropical lowlands. Its combination of high equatorial temperatures, a variety of rainfall regimes, and rich volcanic soils has resulted in a diverse array of vegetation types dominated by rainforest, but also including mesic forest, seasonal dry forest, savannah, alpine grassland, and tundra. This high habitat (β) diversity and geological amalgamation of separate terranes and island-arc systems has promoted the evolution of an enormous, largely endemic, biota in which closely related species replace one another along altitudinal gradients, as well as across island arc systems, mountain ranges, and adjacent peaks and uplands.


Areas to be surveyed

Of the proposed 15 expedition sites, we undertook 11 collecting expeditions from 2010-2014, scattered around Papua New Guinea, concentrated in the Southeastern Peninsula and adjacent islands because of their especially poorly collected history.

Expeditions sites marked on the map (above) included:
1. Finisterre Range, Madang Province (Expedition 1 - 2010)
3. Whiteman Range, West New Britain Province (Expedition 3, 4 - 2011)
4. Sibium Mountains, Oro (Northern) Province (Expedition 7 - 2013)
6. Mount Strong, Central/Morobe Province (Expedition 5 - 2012)

Other expeditions included:
Kamiali, Morobe Province (Expedition 2 - 2011)
Siboma, Morobe Province (Expedition 6 - 2012)
Mount Yule, Central Province (Expedition 8 - 2013)
Mount Gerebu, Central Province (Expedition 9 -2013)
Oomsis, Morobe Province (Expedition 10 - 2014)
Mount Gahavisuka, Eastern Highlands Province (Expedition 11, Drs Si He & Michael Sundue - 2013)


This project is funded in part by the National Science Foundation (DEB-0950207).

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