New Guinea freshwater swamp forests

• Category: Inland Aquatic Biomes
• Geographic Location: South Pacific Ocean
• Summary: The New Guinea freshwater swamp forests are filled with a wide array of flora and fauna, including some species indigenous to this inland aquatic biome. Ecosystems important to the survival of Indigenous people are threatened by mining wastes and logging.

New Guinea, the second-biggest island in the world, was once attached to Australia and features a range of lowland, freshwater, and peat swamp forests across its Irian Jaya and Papua New Guinea sectors. The area of the Freshwater Swamp Forests biome mainly encompasses the foothills on the northern side of the central cordillera and down to the north coastal areas.

The region’s climate is tropical, with the temperature of the coastal plains averaging 82 Fahrenheit (F) (28 Celsius [C]), 79 (26 C) in the inland and lower mountain areas, and 73 F (23 C) in the higher mountain regions. The area’s relative humidity is a high 70 to 90 percent. There is a somewhat more dry season, June to September, while the rainy season is December to March. The western and northern parts of New Guinea get the most rainfall, which averages 400 inches (10,160 millimeters) per year.

Flora and Fauna

The island of New Guinea represents approximately 1 percent of the world’s landmass—but is home to nearly 10 percent of its vertebrate species and 7 percent of its vascular plant types. It also is home to the southern crowned pigeon (Goura scheepmakeri), considered the largest known pigeon, as well as the smallest parrot, the red-breasted pygmy parrot (Micropsitta finschii), and the longest lizard, Salvadore’s monitor lizard (Varanus salvadorii). New Guinea is home to the world’s largest butterfly, the Queen Alexandra birdwing (Ornithoptera alexandrae), and the conifer Araucaria, which can grow up to 230 feet (70 meters) and is thought to be the tallest tropical tree species on the planet.

Lowland swamp forests are located extensively in the island's northern portion, particularly near the Sepik River. This area contains numerous habitats, including herbaceous swamp, Leersia grass swamp, Saccharum-phragmites grass swamp, Pseudoraphis grass swamp, mixed swamp savanna, Melaleuca swamp savanna, mixed swamp woodland, sago swamp woodland, pandan swamp woodland, mixed swamp forest, Campnosperma swamp forest, Teminalia swamp forest, and Melaleuca swamp forest.

The swamp forests include small- to medium-crowned dense to open areas, with a 65- to 98-foot (20- to 30-meter) canopy. Sago palm (Metroxylon sagu) and Pandanus spp. palm generally are located in this subcanopy, which also features Campnosperma brevipetiolata, C. auriculata, Terminalia canaliculata, Nauclea coadunata, and Syzygium spp., with Myristica hollrungii in delta areas.

The canopy along the Mamberamo River is approximately 147 feet (45 meters) high; it includes ficus and Pittosporum ramiflorum, as well as Timonius, Dillenia, and Nauclea.

The most abundant forest type in this ecoregion is lowland broadleaf evergreen, which is split into alluvial and hill varieties. The lowland alluvial forest has a multitiered and irregular canopy with many emergents, and a shrub and herb layer understory with climbers, epiphytes, and ferns. Palms are most common in the shrub layer. The canopy trees include Pometia pinnata, Octomeles sumatrana, Ficus spp., Alstonia scholaris, and Terminalia spp. Additional important genera include Pterocarpous, Artocarpus, Planchonella, Canarium, Elaeocarpus, Cryptocarya, Celtis, Dracontomelum, Sysoxylum, Syzygium, Vitex, Spondias, and Intsia.

The lowland hill forest contains a more open shrub layer than the lowland broadleaf evergreen forest, and a denser herb layer. The dominant canopy trees are Pometia, Canarium, Anisoptera, Cryptocarya, Terminalia, Syzygium, Ficus, Celtis, Dysoxylum, Buchanania, Koompassia, Dillenia, Eucalyptopsis, Vatica, and Hopea. Dense stands of Araucaria are scattered throughout this area.

New Guinea is home to more than 2,000 species of orchids and an equal number of ferns. Eight out of ten of these plants are found nowhere else in the world, that is, they are endemic here. Of the climbing plants, there are climbing palms or rattans that can grow to 787 feet (240 meters). Over 13,600 vascular plant species live in the swamp forests.

Biodiversity

There are seventy-six mammal species in this ecoregion, including thirteen that are endemic or near-endemic, such as tube-nosed bat (Nyctimene draconilla) and greater sheath-tailed bat (Emballonura furax). The western part of the ecoregion is the only known site in New Guinea for the western ringtail possum (Pseudochirops albertisi). Others include Echymipera clara, Dorcopsis muelleri, Dorcopsis hageni, Emballonura furax, Hipposideros wollastoni, and Paraleptomys rufilatus.

The area is home to two endangred species of tree kangroo, the ifola tree kangaroo and Goodfellow's tree kangaroo (Dendrolagus notatus and D. goodfellowi), as well as the long-beaked echidna (Zaglossus bruijnii) and the mountain cuscus (Phalanger carmelitae). New Guinea has a diverse animal population, including monotremes (mammals that lay eggs). These include the short-beaked echidna or spiny anteater (Tachyglossus aculeatus) and the long-beaked echidna. Other animals include the forest wallaby (Dorcopsulus macleayi), which is not found anywhere else, and seventy-five bat species and rodents.

Among the region’s many reptiles are the Papuan olive python (Apodora papuana); New Guinea snapping turtle (Elseya novaeguineae); lined gecko, which also is known as the striped gecko (Gekko vittatus); carpet python (Morelia spilota), and spotted tree monitor (Varanus timorensis).

There are more than 750 bird species, approximately half of which are endemic to New Guinea. Local bird families include Ptilonorhynchidae, Eopsaltria, Meliphagidae, and Paradisaeidae. Among the sixteen endemic or near-endemic species is the Salvadori’s fig-parrot (Psittaculirostris salvadorii). Others include Edwards’s fig-parrot (P. edwardsii), Papuan swiftlet (Aerodramus papuensis), brown-headed crow (Corvus fuscicapillus), white-bellied whistler (Pachycephala leucogastra), brown-capped jewel-babbler (Ptilorrhoa geislerorum), green-backed robin (Pachycephalopsis hattamensis), and pale-billed sicklebill (Drepanornis bruijnii). There are more than forty different kinds of birds of paradise, the landmark species of the island.

Many of the fish in freshwater here are migratory, coming from or going to the sea to spawn, such as the tarpon (Megalops cyprinoides) and barramundi (Lates calcarifer). Others are permanent inhabitants of freshwater habitats, such as fork-tailed catfish (Ariidae), gudgeons (Cyprinidae), gobies (Gobiidae), grunters (Terapontidae), and jacks (Carangidae). In the lowland rivers, where the waters are turbid and silty, are catfish, croakers (Sciaenidae), silver biddies (Gerreidae), and ponyfish (Leiognathidae). In the floodplain lakes, swamps, and backwaters are rainbow fish, gobies, gudgeons, and catfish.

Environmental Issues

One of Southeast Asia-Oceania's largest protected areas is Lorentz National Park in West Papua. At 5.8 million acres (2.35 million hectares), this World Heritage Site stretches 93 miles (150 kilometers) to the Arafura Sea, crossing a large area of freshwater swamp forest. The largest protected area is the Pulau Dolok Wildlife Reserve (Suaka Margasatwa), covering 2,702 square miles (700,000 square kilometers), and the small Danau Bian Wildlife Reserve protects the reservoir in the Fly River region.

Because population density is low in the swampy areas of lowland New Guinea, the Indigenous people have presented little threat to biodiversity except for their overhunting. Indigenous communities are critical in the fight against climate change and protecting Earth’s ecosystems. Many Indigenous communities in New Guinea, such as the Inaugl Tribe in the Bismarck Forest Corridor, have taken legal action to secure and protect their land.

Logging also has been a threat, particularly in better-drained areas; this mostly impacts bird habitat. Though logging remains an issue in the twenty-first century, widespread deforestation due to palm oil development has harmed the region's forests more significantly. Palm oil plantations continued expansion in the 2020s, particularly in the southern freshwater swamp forests.

Hunting for bird meat and feathers may contribute to the decline of several bird species, such as the southern and northern cassowary (Casuarius casuarius and C. unappendiculatus), Salvadori’s teal (Salvadorina waigiuensis), the black honey buzzard (Henicopernis infuscatus), and the New Guinea harpy eagle (Harpyopsis novaeguineae). Other threats to the area come from open-pit copper and gold mines in the mountains upstream from large expanses of wetlands. The Indonesian and Papua New Guinea governments allowed three of the world’s largest mines to operate without a system to retain mine tailings, often discharged into local waterways. Researchers have identified the negative impact of deforestation and mining on the wetlands of the Lake Kutubu ecosystem, which are known to be feeding, nursery, and spawning grounds for endemic fish species.

Climate change has created an imbalance in this ecosystem, causing shore erosion and affecting the salinity of the waterways. Increased rain has altered the water flow of rivers in the region, impacting the biome's flora and fauna. As sea levels rise, the salinity of the freshwater swamps is threatened. If this trend continues, the region could become a brackish environment, which would be inhospitable for most life in the biome.

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