Lesser Sunda Islands

The Lesser Sunda Islands (Indonesian: Nusa Tenggara) are a group of islands located in the south-central part of the Malay Archipelago. Together with the larger Sunda Islands to the west, they make up the Sunda Islands.

Administration

They are divided into the Indonesian provinces of Bali, the Western Lesser Sunda Islands (Indonesian: Nusa Tenggara Barat), the Eastern Lesser Sunda Islands (Indonesian: Nusa Tenggara Timur), Moluccas (Indonesian: Maluku) and the independent state of East Timor (Tetun: Repúblika Demokrátika Timor Lorosa'e, and in Portuguese: Democratic Republic of Timor-Leste).

Islands of the group

The main islands of the group are the following:

Geology

The Lesser Sunda Islands are part of the Sunda arc and extend along the collision line between two tectonic plates, the Eurasian and the Indo-Australian, and constitute one of the most complex and volcanically active regions. of the world. This tectonic activity determines both the biodiversity and the distribution and formation of the islands.

The chain of islands located in the north of the region are of volcanic origin and geologically young since their formation dates back 15 million years. They have never been part of a continental mass, with the exception of Bali, which belonged to the Sunda continental shelf in the Pleistocene. Bali was separated from the rest of the islands by the deep Lombok Strait that coincides with the Wallace Trench Passage. To the east of this strait, most of the islands were linked in a long island chain about 650 km long that included the present-day islands of Lombok, Sumbawa, Komodo, Flores, Solor, Adonara, and Lembata. To the east, Pantar and Alor were a single island. The islands located to the south of the chain, such as Timor, Sumba and Babar, have always been isolated and constitute a distinct geological entity.

Due to their particular geological and biological isolation, the minor Sunda Islands (except Bali) belong to the Wallacea, a transitional biogeographic region between Asia and Oceania.

Ecology

The Lesser Sunda Islands differ from the large islands of Java or Sumatra in that they are made up of many small islands, sometimes divided by deep ocean trenches. The movement of flora and fauna between the islands is limited, which has led to the evolution of a high rate of localized species, the most famous of which is the Komodo dragon. As described by Alfred Wallace in The Malay Archipelago, the Wallace Line passes between Bali and Lombok, along the deep waters of the Lombok Strait, which formed a water barrier even when sea level was lower and linked the now separated islands and land masses to both sides. The islands located east of the Lombok Strait are part of Wallacea, so they are characterized by a mixture of fauna of Asian and Australian origin in this region. Asian species predominate in the Lesser Sundas: The Weber Line, which marks the boundary between the parts of Wallacea with mainly Asian and Australian species respectively, runs to the east of the group. These islands have the driest climate in Indonesia, and dry broadleaf tropical forests predominate, in contrast to the humid tropical forests that prevail in most of Indonesia.

Ecoregions

The Lesser Sunda Islands are divided into six ecoregions:

• The wet forests of East Java-Bali and the wet mountain forests of East Java-Bali cover Bali, which is the only one of the Lesser Sonda Islands found in the Indomeal kingdom, and is not part of Wallacea. Bali was once joined to the Asian continent (see Sundaland), and it was home to large Asian mammals such as Asian elephants and Bali's late tiger.
• The deciduous forests of the Sundas Menores include the chain of northern islands, from Lombok and Sumbawa to the east to Flores and Alor. The highest slopes of the islands contain forests of high conifers Podocarpus and Engelhardias with a sotobosque of lianas, epiphytes and orchids such as Corybas, Corymborkis and Malaxis (powdermouth), while the coastal plains were originally savannahs of pastures like the savannah with palm trees Borassus flabellifer on the coasts Although most of the vegetation of these islands is dry forest, there are also tropical forest stains in them, especially in the low areas and on the banks of the rivers of Komodo, and there is a particular area of thorny dry forest on the southeast coast of Lombok. The spiny trees used to be more common in the coastal areas of the islands, but have been largely eliminated. These islands host unique species, such as seventeen endemic birds (of the 273 found on the islands). The endemic mammals are the musaraña de Flores (Suncus mertensi), in danger of extinction, the vulnerable rat of Komodo (Komodomys rintjanus), and the flying fox of Lombok (Pteropus lombocensis), the long-eared bat of Sunda (Nyctophilus heran), while the carn
• The ecoregion of the deciduous forests of Sumba includes the latter.
• The ecoregion of Timor and Wetar's deciduous forests includes Timor, Wetar, Rote and Savu.
• The ecoregion of wet deciduous forests of the Banda Sea islands, the most humid, includes the Barat Daya Islands (except Wetar), the Tanimbar Islands and the Kai Islands.

Threats and preservation

More than half of the islands' original vegetation has been cleared for planting rice and other crops, for settlements, and for subsequent forest fires. Only Sumbawa now contains a large area of intact natural forest, while Komodo, Rincah and Padar are now protected as Komodo National Park.

Although many ecological problems affect both small islands and large land masses, small islands suffer from their own particular problems and are highly exposed to external forces. Development pressures on small islands are increasing, although their effects are not always anticipated. Although Indonesia is richly endowed with natural resources, the resources of the small islands of Nusa Tenggara are limited and specialized; Furthermore, human resources in particular are limited.

General observations about small islands that may apply to Nusa Tenggara are:

• A greater proportion of the land mass will be affected by volcanic activity, earthquakes, detachments and damage caused by cyclones;
• Climates are more prone to maritime influence;
• The catchment areas are smaller and the degree of erosion is higher;
• Increased proportion of land mass is made up of coastal areas;
• A higher degree of environmental specialization, including a higher proportion of endemic species in a depaid general community;
• Societies may retain a strong sense of culture by having developed in relative isolation;
• Small island populations are more likely to be affected by economic migration.