New Caledonia Dry Forests

• Category: Forest Biomes
• Geographic Location: Pacific Ocean
• Summary: Supporting great biodiversity, this biome is subject to impacts from climactic changes that could imperil habitats of native species.

New Caledonia is a French-controlled archipelago in Melanesia, about 930 miles (1,497 kilometers) east of Australia. It includes a land area of 7,172 square miles (18,575 square kilometers). The tropical climate features a hot, humid summer from November to March with temperatures between 80 to 86 degrees Fahrenheit (F) (27 to 30 degrees Celsius (C)) and a cool, dry winter between 68 to 74 degrees F (20 to 23 degrees C) from June to August.

Rainfall amounts vary widely, with 118 inches (3,000 millimeters) recorded in Galarino, the Northern Province, three times the average total of the west coast. Between December and April, tropical depressions and cyclones can cause winds of 62 miles per hour (100 kilometers per hour) with gusts of 155 miles per hour (250 kilometers per hour) and abundant rainfall. A quite violent cyclone hit New Caledonia in January 2011.

The main island, Grand Terre, has some of the most concentrated species diversity in the world. While the surrounding islands are recent and volcanic, Grand Terre was originally a piece of the supercontinent Gondwanaland that separated from Australia 85 million years ago. This isolation has driven much of the ecoregion’s diversity. The dry forests of New Caledonia are found only on Grand Terre, on the western side of the island. They harbor fifty-nine endemic plant species, that is, species found only here. The present-day forests represent a surviving remnant of the vast, prehistoric ecosystem that once existed. Because they are often cleared for agricultural land or logging, tropical dry forests are among the most threatened forest types worldwide.

Biodiversity

The best known of those endemic plants is Captaincookia margaretae (also known as Ixora margaretae), a flowering variety of the madder family (Rubiaceae), with brilliant red flowers. Because the dry forests have been so severely reduced to create agricultural land and settlements since Europeans colonized the island in the 19th century, C. margaretae today is found in only six locations. It is the only member of its genus. The introduction of the Rusa deer (Cervus timorensis russa) to the island posed another threat, as the deer adapted well to the habitat and became a major consumer of plant life; it damages trees by rubbing its antlers against tree stems.

The only gymnosperm common in the ecoregion is queen sago (Cycas circinalis), a cycad with poisonous seeds that grows near the western coast. Other common plants include the verbena family (Verbenaceae), flowering plants of the Premna genus, shrubs and small trees of the Dodonaea genus, flowering plants of a Pittosporum genus that is shared with Australia, gardenias, and Canthium shrubs.

Seasonal wildfires have begun turning patches of dry forest into shrubland, where Acacia spirorbis and white popinac (Leucaena leucocephala) dominate. White popinac is highly invasive; it continues to spread whenever surrounding vegetation has been cleared, allowing it entry to the ecosystem. Pittosporum tanianum, a tree species discovered in the 1980s, was recently declared extinct after a wildfire left no surviving specimens. Fire poses a danger both in the form of naturally occurring wildfires and through the use of fire-setting as a means of protest by young unemployed men in rural areas.

Newly introduced species also pose significant threats, from the neotropical ant Wassmannia auropunctata, which has diminished native lizard and invertebrate populations through competition, to the introduction of cats, rats, dogs, and pigs, which have taken serious tolls on various native flora and fauna.

Several species of bat in the Nyctophilus genus live on the island, including N. nebulosus, the New Caledonian long-eared bat, a species discovered in 2010 that may be the island’s only endemic vertebrate. Near-endemic wildlife found in the dry forests and a few other places include the New Caledonia wattled bat (Chalinolobus neocaledonicus), ornate flying fox (Pteropus ornatus), long-tailed fruit bat (Notopteris macdonaldi), and New Caledonia flying fox (P. vetulus).

There are twenty-three near-endemic bird species, including the white-bellied goshawk (Accipiter haplochrous), red-bellied fruit dove (Ptilinopus greyii), New Caledonian imperial pigeon (Ducula goliath), horned parakeet (Eunymphicus cornutus), New Caledonian owlet-nightjar (Aegotheles savesi), Melanesian cuckoo-shrike (Coracina analis), long-tailed triller (Lalage leucopyga), New Caledonian grassbird (Megalurulus mariei), fan-tailed gerygone (Gerygone flavolateralis), yellow-bellied robin (Eopsaltria flaviventris), New Caledonian flycatcher (Myiagra caledonica), southern shrikebill (Clytorhynchus pachycephaloides), streaked fantail (Rhipidura spilodera), New Caledonian whistler (Pachycephala caledonica), green-backed white-eye (Zosterops xanthochrous), New Caledonian myzomela (Myzomela caledonica), dark-brown honeyeater (Lichmera incana), New Caledonian friarbird (Philemon diemenensis), barred honeyeater (Phylidonyris undulata), red-throated parrotfinch (Erythrura psittacea), striated starling (Aplonis striata), and New Caledonian crow (Corvus moneduloides).

The New Caledonian crow is found only here and in the Loyalty Islands and has increasingly been the subject of studies of animal intelligence. The crow is a tool-using bird species and perhaps the only nonhuman species with relatively advanced tool skills. Scientists have observed the crow innovate by modifying existing tools to create new ones and then passing the tool-making method on to other members of its group. Scientists have seen New Caledonian crows bending wires to create hooks to retrieve pieces of food. In the inhabited parts of New Caledonia, crows have been observed placing nuts in the street, waiting for a car to drive over them to crack the shells, and then waiting at the crosswalk before crossing with pedestrians to retrieve the cracked nut safely. The crow has also been observed making new copies of previously used tools from new materials to take advantage of what is available. Again, it is the only nonhuman species observed doing so.

Environmental Threats

New Caledonia’s biodiversity is threatened by introduced species, deforestation from logging, mining, uncontrolled fires, agricultural and urban development, and tourism, all of which impact the fragile ecosystem. The New Caledonian rail, last seen about 1890, and the New Caledonian lorikeet, not seen since 1976, are considered critically endangered if not extinct. The New Caledonian owlet-nightjar have been pushed to remote areas, and the New Caledonian crested gecko was thought extinct until it was rediscovered in 1994. Native grasses are being outcompeted by introduced species, such as molasses grass (Melinis minutiflora)—used for livestock feed—and native trees that are a part of government-created protective parks and reserves.

New Caledonia is a conservation priority for many environmental organizations, which have lobbied to preserve the archipelago’s unique ecosystems. However, so far, governmental support has not provided the protection it needs. Efforts to secure the United Nations Educational, Science, and Cultural Organization (UNESCO) World Heritage Site status in certain areas have failed, as environmental interests conflict with those of regional governments and mining and development interests. The government has taken steps to preserve the dry forest. For example, Noumeau has four dry forest protected areas, including the Forest Park and Zoo. It continues to work to create nature sanctuaries.

The impact of climate change has not been thoroughly studied in this biome. However, recent data revealed that temperature and rainfall variations are known to imperil the survival of dry forest ecosystems. Changing rainfall totals could alter the habitat, and more fires could exacerbate damage. Climate change could also diminish the resilience of these natural habitats to recover and, instead, provide a more favorable environment to advance the spread of invasive species.

Bibliography

Allenbach, Michel. "The Natural Environment of New Caledonia." Understanding New Caledonia. Gravelat, Caroline, editor. Sutton, Elaine, translator. UP of New Caledonia, 2021.

Bouchet, P., and Y. I. Kantor. “New Caledonia: The Major Centre of Biodiversity for Volutomitrid Molluscs.” Systematics and Biodiversity, vol. 1, no. 4, 2003.

Gillespie, Thomas W., and Tanquy Jaffe. “Tropical Dry Forests in New Caledonia.” Biodiversity and Conservation, vol. 12, no. 8, 2003.

Pennington, Toby. Neotropical Savannas and Seasonally Dry Forests. CRC Press, 2006.

Rodary, Estienne. "Check for Which Environmental Policies for New Caledonia? Estienne Rodary." Geographies of New Caledonia-Kanaky: Environments, Politics and Cultures, 2024, p. 13.

Steadman, D. Extinction and Biogeography in Tropical Pacific Birds. Chicago: University of Chicago Press, 2006.