Vanuatu rainforests

Category: Forest Biomes.

Geographic Location: Pacific Ocean.

Summary: The Vanuatu archipelago features rugged terrain with a patchwork of native and invasive forest cover and some remarkable synergy between fruit bats and trees.

The Vanuatu archipelago in the South Pacific Ocean is comprised of more than 80 islands in a grouping roughly 800 miles (1,300 kilometers) in length. The location is some 1,100 miles (1,800 kilometers) east of Australia and 105 miles (170 kilometers) south of the Solomon Islands. The total land area of the Vanuatu nation is about 4,750 square miles (12,300 square kilometers).

Topography and Climate

The capital, Port Vila, is on the island of Efate. The archipelago is part of the Pacific Ring of Fire, with volcanic activity as the origin of each island, and an active seismic regime. While there are some stretches of flat, sandy beaches, most shorelines are rocky, with water depth dropping quickly. The same steep topography continues inland; there is little bottomland, savanna, or meadow area. Soils tend to be shallow or loose and subject to landslides. Freshwater is not abundant.

Because of the steep nature of the islands, little flat or bottomland is available. Forest tracts are extensive, covering nearly 77 percent of the land area. Mid-height forests, 66–99 feet (20–30 meters) in height, and low forests, 33–66 feet (10–20 meters) in height, comprise approximately 35 percent of the total. The largest island, Espiritu Santo, holds the tallest mountain peak, Mount Tabwemasana, at 6,165 feet (1,879 meters).

Biodiversity

The discovery of extremely valuable sandalwood (Santalum austrocaledonicum) growing wild in Vanuatu and neighboring New Caledonia caused land-rush harvesting in the mid-19th century, and nearly 100 percent of the wild plants were removed. Strict regulations adopted in 1987, accompanied by concentrated horticultural efforts, may have saved this species. The tree has now recovered well, but the lingering effects of the clear-cutting and habitat degradation on the other native flora and fauna of the islands has yet to be determined.

Timber harvesting of the remaining and replanted sandalwood and other trees is now more tightly controlled, and currently only two species here are being harvested at or below sustainable levels: whitewood (Endospermaum medullosum) and melektree (Antiaris toxicara), However, some intact native forests still remain, primarily in steep mountainside locations.

Vanuatu rainforests tend to be shorter in height than similar island forests, with nearly all the trees being shorter than 100 feet (30 meters) in height. This is likely a result of multiple factors, including increased seismic activity and landslide, location of the islands in a zone of frequent cyclones, poor soil formation due to steep terrain and high rainfall levels, and human activities, such as habitat fragmentation and erosion during World War II, when control of the islands was transferred between the Japanese and Allies in several heavily fought engagements.

One notable type of fauna found in the Vanuatu Rainforests biome is the fruit bat, or flying fox. Fruit bats are distributed throughout Old World Tropics regions, including the islands of the southern Indian and Pacific Oceans. Many such islands have their own endemic species (those found nowhere else), often at low densities, which makes them of extreme importance for conservation and research. Vanuatu has five species: four in the genus Pteropus and one in the genus Notopteris. All are declining and most face risk of extinction.

Fruit bats are extremely valuable to the ecosystem in that they serve as pollinators or seed dispersers for native trees. For example, on the Samoan Islands, between 80 and 100 percent of all tree seeds found on the forest floor are distributed by fruit bats. In Vanuatu, some bat-dependent tree species are of considerable economic importance, such as ebony (Diospiros spp.) and mahogany (Sweitenia spp.).

Many forest trees have co-evolved with the fruit bats in order to increase the likelihood of pollination or seed dispersal. Some tree species, for instance, produce prodigious quantities of nectar to attract the bats. Other trees bloom only at night to prevent other potential pollinators from capturing the resource. On the island of Guam, where the two endemic species of fruit bats have been extirpated by brown tree snakes (Boiga irregularis) and human encroachment, several tree species have stopped blooming.

Fruit bats tend to suffer heavily at the hands of humans. Most islands are protein-poor environments, and given that fruit bats are relatively large and conspicuously roost communally during the day (often on exposed tree branches), they are easy targets for hunters. Fruit bats, although protected by the government in many areas, are sold in markets and served as delicacies in restaurants across many areas of the Pacific. Most species are declining, and two on Vanuatu are listed as endangered.

There is a discrepancy in scientific literature on whether there are four or five species of fruit bat on the Vanuatu Islands chain, and whether or not they are all endemic. For example, the long-tailed fruit bat (Notopteris macdonaldi) is listed as a Vanuatu endemic, yet it is also found in Fiji and New Caledonia. In either case, it is considered an endangered species.

Despite being tropical, with heavy vegetation cover and moist conditions, Vanuatu has fewer vertebrate species than other island chains of similar size. Besides the four to five fruit bat species, there are eight species of smaller bats (family Microchiroptera) and no other native species of land mammals. The domesticated and feral mammals are typical of many places humans have colonized, and include three species of rat (Rattus spp.), mouse (Mus musculus), cattle (Bos taurus), goats (Capra hircus), pigs (Sus scrofa), feral cats, and dogs. Of particular note are the feral pigs, which cause massive forest destruction through their foraging on young plants and the creation of wallows they use for cooling and protection from parasites. This habitat destruction, coupled with high rainfall, results in serious erosion problems and resulting drops in water quality.

There are 19 species of lizards in the Vanuatu Rainforests biome, one of which is declining to the point of extinction, and two snakes, the flower pot snake (Ramphotyphlops braminus) and the Fiji boa (Candoia bibroni). Both snakes are wide-range dispersers and are found throughout the Southern Hemisphere, including most of the South Pacific Islands.

A total of 139 bird species have been recorded on Vanuatu; most are not restricted to the rainforest highlands. Of the species present, nine are endemic. Eight have been introduced by humans and have become established. Twelve species are threatened or endangered on a global basis.

Although found in a variety of locations, rainforest species of interest include the green palm lorikeet (Charmosyna palmarum), Vanuatu mountain pigeon (Ducula bakeri), peregrine falcon (Falco peregrinus nesiotes), Vanuatu flycatcher (Neolalage banksiana), and golden whistler (Pachycephala pectoralis). Populations of these species vary widely, in part due to the cyclonic nature of the weather. Large population crashes are noted after severe storm activity, yet rapid recoveries tend to occur during intervening years.

Threats and Conservation

As an island nation, Vanuatu is severely threatened by rising sea levels caused by global climate change. Since 1993, sea levels have risen by an average of 6 millimeters per year (0.24 inches) per year. At the same time, the island has also been negatively impacted by extreme weather. In response, Vanuatu’s government proposed the creation of a loss-and-damage fund that would both proactively combat climate change while remedying the effects it has already had on the nation. The proposed fund would carry a $178 million price tag by 2030. It would include commitments to end the use of fossil fuels, greatly reduce emissions, and provide money to repair damage and reimburse losses caused by climate change.

Bibliography

Bowen, J. 1997. “The Status of the Avifauna of Loru Protected Area, Santo, Vanuatu.” Bird Conservation International 7 (1997).

Bule, L. and G. Daruhi. 1990. “Status of Sandalwood Resources in Vanuatu.” In Proceedings of the Symposium on Sandalwood in the Pacific, by L. Hamilton and C. Conrad. Berkeley, CA: Pacific Southwest Research Station, U.S. Forest Service, 1990.

Mourgues, A. Republic of Vanuatu Environment Profile. Port Vila, Vanuatu: Government of Vanuatu, 2005.

Taylor, Michael. “Has Vanuatu Just Made the Most Significant Change to Any Country’s Climate Change Commitments?” World Economic Forum, 15 Aug. 2022, www.weforum.org/agenda/2022/08/vanuatu-breaks-ground-with-loss-and-damage-costing-in-new-climate-plan. Accessed 19 Aug. 2022.