The Biodiversity Hotspot Of Wallacea

Wallacea is home to an abundance of flora and fauna.

The Location Of Wallacea

Wallacea refers to a group of islands, mainly Indonesian, separated from the Australian and Asian continental shelves by deep water straits. The biogeographical region includes Sulawesi, Lombok, Halmahera, Buru, Seram, Flores, Sumbawa, Sumba, and several other smaller islands. Sulawesi is the largest island of the group. Wallacea occupies a total land area of 347,000 square km. Sundaland lies to the west and Near Oceania to the east of Wallacea.

The Origins Of Wallacea’s Unique Biodiversity

A very interesting feature of Wallacea is the unique collection of flora and fauna in the region. The Sundaland islands to the east of the region exhibit flora and fauna similar to that in East Asia. Apes, rhinoceros, tigers, etc., are the notable fauna of the region. The islands located to the east of the Wallacea region exhibit flora and fauna closely related to the marsupials and birds of Australasia. In between, Wallacea exhibits signs of both.

During the ice ages, when the sea level was not as high as it is today, a number of species of animals managed to move from the Asian mainland to the Sundaland islands across the exposed Sunda shelf linking the mainland and the Sundaland islands to each other. However, these animals were unable to cross the deeper straits that led to Wallacea. Thus, only those species of animals that were able to cross the open ocean from continental Asia managed to reach Wallacea. Hence, the islands here have very few species of land animals. Similarly, Australia was linked to some of the islands like New Guinea by shallow continental shelves that allowed the passage of animals between the places. However, many of the marsupials and land birds found in Australia, the Aru Islands, New Guinea, etc., are not found in Wallacea.

The Flora Of Wallacea

Originally, Wallacea was nearly completely covered by forested land mainly tropical moist broadleaf forests. Some areas of the islands also featured tropical dry broadleaf forest. Montane and subalpine forests are present on the higher altitudes. Coastal areas feature mangrove wetlands. Over 10,000 species of flora grow in Wallacea. 15% or nearly 1,500 species of flora are endemic in nature.

The Fauna Of Wallacea

Today, Wallacea is home to a number of endemic species that are under threat thus leading to the designation of the biogeographic region as a biodiversity hotspot. Even the islands of Wallacea have their own distinct species diversity.

Of the 1,142 species of terrestrial vertebrates found in Wallacea, 429 are endemic in nature. Some of the notable endemic fauna of the region includes the anoa (dwarf buffalo), and the babirusa (deer pig). Several species of primates also live here. The island of Seram has a rich collection of birds and butterflies. The Amboina king parrot is the most famous them.

Threats To Wallacea’s Biodiversity

Today, the flora and fauna of Wallacea are facing significant challenges posed by human activities. Large scale deforestation, developmental activities, habitat destruction, hunting and poaching, and also climate change induced sea level rise are all factors responsible for the declining numbers of Wallacea’s endemic animals and plants. Only 45% of the region retains forest cover in some form. Only 15% or 52,017 square km of this forest region is in the pristine state. 82 species of threatened including 6 critically endangered species of terrestrial vertebrates inhabit Wallacea.


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