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Lesser Sunda Islands

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The Lesser Sunda Islands are a diverse archipelago located in Indonesia.

Lesser Sunda Islands
Lesser Sunda Islands

They are also known as the Nusa Tenggara Islands. This name comes from the words *nusa*, meaning island, and *tenggara*, meaning southeast. These islands sit east of the island of Java. Most of the archipelago is located within a transition zone called Wallacea. However, the province of Bali sits west of the Wallace Line. Bali is part of the Sunda Shelf rather than the Wallacea region. Together with the Greater Sunda Islands, they form the larger Sunda Islands group.

SundaIslands.A2003242.0225.500m
SundaIslands.A2003242.0225.500m

The geology of the islands is incredibly complex. They sit at the collision point of two massive tectonic plates. This interaction created the Sunda Arc, which is a volcanic arc. This arc was formed by subduction along the Sunda Trench in the Java Sea. The islands can be divided into two distinct geological groups. The northern archipelago includes Bali, Lombok, Sumbawa, Flores, and Wetar. These islands are volcanic in origin. Some of these volcanoes are still active, such as Mount Rinjani on Lombok. Others, like Ilikedeka on Flores, are now extinct. The southern archipelago includes islands like Sumba, Timor, and Babar. These islands are non-volcanic and appear to belong to the Australian plate.

Geological formation began during the Pliocene epoch. This happened about 15 million years ago. The process was triggered by the collision between the Australian and Asian plates. Scientists have studied this region since Indonesian colonial times. However, the exact progression of how these islands evolved is not fully understood. Theories regarding their geological history changed many times during the late 20th century. The northern islands share similar characteristics with the southern Maluku Islands. This is because they are part of the same continuous island arc. This region remains one of the most geologically active areas in the world.

The islands are separated by deep oceanic trenches. These trenches act as barriers to the movement of plants and animals. This isolation has led to a high rate of localized species. These are species found nowhere else on Earth. A famous example is the Komodo dragon. This lizard is the largest in the world. It can reach three metres in length and weigh 90 kilograms. The dragon lives on Komodo, Rincah, Gili Motang, and the northwest coast of Flores. Other unique animals include the Flores shrew and the Lombok flying fox. The islands also host 17 endemic bird species out of the 273 total species found there.

Climate and ecology also vary across the archipelago. The Lesser Sunda Islands have the driest climate in Indonesia. Most of Indonesia has tropical moist forests. In contrast, these islands are dominated by tropical dry broadleaf forests. You can also find savanna grasses and palm trees on the coasts. In some areas, like the higher slopes, there are forests of Podocarpus conifers. These areas also feature orchids and lianas. The Wallace Line is a significant biological boundary here. It passes through the Lombok Strait between Bali and Lombok. This deep water barrier separates Asian species from Australasian species. The islands east of this line are part of Wallacea, blending wildlife from both regions.

The human population has grown significantly over the last century. In 1930, the population was approximately 3,460,055. Today, more than 17 million people live across the islands. Most of the islands are part of Indonesia. They are divided into provinces like Bali, West Nusa Tenggara, and East Nusa Tenggara. However, the eastern half of Timor and the island of Atauro belong to the nation of Timor Leste. As people have settled, the landscape has changed. More than half of the original vegetation has been cleared. This happened to make room for settlements and crops like rice. Forest fires have also contributed to this loss of habitat.

Protecting these islands is a major challenge. Only Sumbawa still contains a large area of intact natural forest. To help save wildlife, certain areas are now protected. Komodo, Rincah, and Padar are part of the Komodo National Park. Small islands face unique risks compared to large landmasses. They are highly exposed to external forces and environmental changes. These islands are more likely to be affected by volcanic activity and earthquakes. They are also prone to landslips and cyclone damage. Because the islands are small, they have smaller catchment areas. This leads to a higher degree of soil erosion. Managing these limited natural resources is vital for the future of the region.

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