Wallace and Webber Line on Indonesia Archipelago

In plants and animal geography, Alfred Russel Wallace (1823-1913) no closely related. He pioneered modern research about animal geography, apart from Darwin theory. He postulated that there is an imaginary line separating Australis and Asiatic  animals. Wallace held a research about the spread of Indonesia animals and the result was that there are difference between animals on the Eastern and Western part of Indonesia.

Wallace line is a hypothetical line separating Asia and Australasia  geographic animals. The western part is related to Asia species, while on the east related to Australia species. This line passes Malay archipelago, between Borneo and Sulawesi, and between Bali and Lombok and Timor. Having typical animals (especially Sulawesi Island), different than oriental and Australia animals such as : Anoa, mako bird, and black monkey. The different was recorded by Antonio Pigafetta about the biological difference between the Phillipines and Maluku Islands, as recorded by Ferdinand Magellan in 1521. This line then was revised and moved eastward (Sulawesi land) by Webber. The flora and fauna of Asia then determined differently, according to flora and fauna types. This line is then called as ‘Wallace-Webber’

Wallace line regions:
-Sunda Shelf (on the west) 
Sunda Shelf is slab ranges from Oriental region (Asia Continent) and located on the western part of Wallace line. Wallace line is an imaginary line separating flora and fauna on Sunda Self with the further east of Indonesia. This line ranges from north to south, between Kalimantan and Sulawesi, and between Bali and Lombok. This line complies the biologist name, Alfred Russel Wallace, who in 1858, showed the spread of flora and fauna in SUmatera, Kalimantan, Java and Bali resemples to that of Asia continent.

-Sahul Shelf (On the east)
Sahul Shelf is slab ranges from Australesia (Australia Continent) located on the east of Webber line. Weber line is an imaginary line separating flora and fauna in Sahul Shelf and the further west part of Indonesia. This line is longitudinal north to south between Maluku Islands and Papua and between Nusa Tenggara Timur and Australia. This line compkies the biologist name Max Weber, who in 1902, showed that flora and fauna spread in this region resembles to that of Australia’s.

-Wallacea Region /Deep Sea (In the middle)
This slab on fringe of East Asia ranges in the middle of Wallace and Webber Line. This region constitutes of Sulawesi, Sunda Kecil (Nusa Tenggara) and Maluku Islands. Flora and fauna in this region are endemic species and found no where else in this world. Yet, this region has oriental and Australesia elements. Wallace stated that ocean was covered by ice in The Ice Age that flora and fauna in Asia and Australia could come across and gathered in Indonesia. And if Asia animals are more in amount in the western, and Australian also in the eastern, is because if Wallacea region is actually was a       very deep sea through that fauna could not cross and fauna stopped to spread.

Webber line is an imaginary line separating flora and fauna in Sahul Shelf and the further west of Indonesia. This line longitudinally located southward between Maluku Islands and Papua Island and between East Nusa Tenggara and Australia. This line was pioneered by Max Carl Wilhelm Webber who was a German-Dutch zoologist and bio-geographer.

Webber is specially interested in the depth of Lombok Srait, thats eparate Bali and Lombok Island. Previously Webber theorized that the strait is the mark separating  Asia and Australia fauna. But Webber’s finding indicating that the dept of Lombok Strait depth was only 312 m, which means that it is not so deep. After in depth analysis, especially on the consition of fauna in the eastern of Indonesia especially in Celebes and Maluku, Webber theorized that the strong  line separating Asia and Australia was non existent, yet forther east of Indonesia, fauna with Asia typical were less and on the opposite fauna with Australia typical is more in amount.

This research result done by Webber is used by some researchers to move the Walalce line eastward and later this line is called as Webber Line, though Webber did not agree about this imaginary separation as Wallace Imaginary line. Webber imaginary line was popularized by paul Pelseneer in 1904.

In modern view, generally, Wallace and Webber line is a transition zone called as Wallacea. Scientists picture that Wallace line between Borneo and Celebes is the end of Asia Slab, while Webber line is between Celebes and Maluku Islands reflecting balance between fauna Asia and Australia.

As Webber returned from exploring East Indies, he published his research “Zoologische Ergebnisse einer Reise in Niederländisch Ost-Indien”. Generally, the main point of his research was about marine biology focused in migration route of ocean invertebrate  and palagis fishes (who live on middle and upper sea). He found new kind of  fishes and  other ocean animals such as Brachiopoda found in several islands on the eastern of Indonesia such as in Banda, Ambon, Seram, Kei, Sulawesi, Sulu and Selayar. While according Tomascik (1997), expedition Siboga in Indonesia discovered 70 species’ and 27 coral ahermatypic, including 3000 species of sponge. The first Batimetri map ( map of sea bottom configuation) was also created in this expedition.

Animals in oriental and Australis meets in Indonesia archipelago. Also flora mentioned by Webber. The border of those animal and flora species stated by both experts then created an imaginary line separating Asiatic flora and fauna, group of flora fauna on transition between Asiatic and Australis, and group of flora and fauna of Australis.

Therefore Indonesia archipelago consists of 3 flora and fauna groups according to its spread:
1. Asiatic/Oriental
Is located on the western part of Indonesia such as :Pulau Sumatra, Jawa, Bali, and Kalimantan, and other small islands in the vicinity.  Asiatic (western)  and Asia-Australis (middle) is separated by Wallace Line.
a) Mammals, consists of Indian elephant (Kalimantan and Sumatera), Tigers (Java, Bali, Sumatera), Rhino ( Sumatera and Kalimantan), Kancil (Java, Sumatera and Kalimantan), Honey bear (Sumatera and Kalimantan). The interesting is that there is no tigers in Kalimantan and in Sulawesi there are also Asiatic animals such as monkeys, musang, anoa, and rusa. Endemic of this region are one horn rhino in Ujung Kulon, Beo Nias in Nias, Bekantan and Orang Utan in Kalimantan.
b) Reptile: biawak, croc, turtle, lizard, snakes, cuckoos,  bunglon and trenggiling.
c) Aves:  elang bondol, jalak, merak, ayam hutan, burung hantu, kutilang, and other poultries
d) Fish: mujair, arwana, and pesut (mamalia air tawar) at Mahakam River.
e) Insects, : kumbang and butterflies and other endemics insects
Flora on Sunda shelf is also called as Asiatic flora and they have Asia typical plants. For example: rattan, and jackfruit. Tropical rain forest is located in the middle and west of Sumatera and mostly covering Kalimantan. Geologically Sunsa shelf was part of Asia continent. In Sunda self there are endemics plants: 59 species in Kalimantan and 10 in Java. Rafflesia Arnoldii can only be found in Bengkulu, Jambi, and South Sumatera. Tien Soeharto can only be found in North Tapanuli and North Sumatera.

Flora in Sumatra–Kalimantan
Most of Sumatera and Kalimantan area are rain forest climate or Af type according to Koppen Climate. This climate has high humidity and rainfall along the year.Therefore, vegetation type dominating here are tropical forest, which is lush and very heterogeneous. The trees are tall and close to each other, and under the trees grow shorter vegetation of bushes and grasses. Flora of Sumatera-Kalimantan are: (dipterocarpus), various epyphyt (orchid, moss, mushroom and ferns and Rafflesia arnoldii which grows along Bukit Barisan from Aceh to Lampung).

Flora in Jawa–Bali
Java island climate are various with humidity and precipitation is lesser eastward. West Java is dominated with tropical forest Climate (Af) and Tropical Season Climate (Am). Eastward, the climate shift to less precipitation climate. In Bali there is a Savanna Tropical Climate. This yield influence to vegetation pattern. Rainforest covers West Java such as Gede Pangrango, Cobodas, and Pananjung. While in Java, from northern part to Central Java to East Java are Tropical Season forest which leaves fall on dry season. Flora in this area is teak trees dominating East Java and Tropic Savanna dominating Bali. Mountain regions are overgrown by mountain vegetation.

2. Australis
Australis type of Indonesia fauna is also called as East Indonesia Fauna region orSahul Land, constitutes of papua, Aru Islands, and small islands in the vicinity. East Indonesia Fauna Region (Australis Type )  and Middle Indonesia Fauna (Asia-Australis Type)  is separated by Webber Line.

Fauna in this region are:.
1) Mammals:  kangaroo, walabi, bears, koala, nokdiak (landak Irian), oposum layang (pemanjat berkantung), kuskus, biawak, kanguru pohon, and bats
2) Reptiles: crocs, biawak, snakes, lizard and turtles.
3) Amphibia : tree frog, flying frog and water frog.
4) Aves :  akatua, beo, nuri, raja udang, cendrawasih, and kasuari.
5) Fish: arwana and other fresh water fishes with less amount in species than in western and middle part of Indonesia.

Flora in Sahul is called as Australis as the flora resembles as that of Australia’s. Sahul consists of Irian Jaya and small islands in the vicinity with typical of North Australia tropical forest which is very lush and evergreen.  Inside the forest there are thousands of big and high plants (up to 50 m), with lush leaves that sun could not shine to the earth surface and tendrils. There are many species of high quality and economic trees. On the coast there are mangrove forest and pandanus, while on swamp there are sago trees. On Mountains can be found Rhododendron, an endemic fauna.

3. Transition Zone
This zone is also called as Asia-Australis Type or Central Indonesia Fauna Zone or Wallacea Zone.
a) Mamalia :  anoa, babi rusa, tapir, ikan duyung, kuskus, black monkeys, bears, tarsius, monyet seba, horse, cows, and banteng.
b) Amphibia:  tree, flying and water frog
c) Reptile : snake, crocs, biawak and komodo
d) Aves : dewata, maleo, mandar, raja udang, bird eating bee, rangkong, kakatua, merpati, and swan.
This zone consists of : Sulawesi, Nusa Tenggara Islands, Timor Island and Maluku Islands. They have dry climate and low humidity that other parts of Indonesia. These islands are called as transition zone as they have flora resembles to that of dry zone in Maluku, Nusa Tenggara , Java and The Phillipines. On mountain there are flora as on Kalimantan. While on coastal  and low land resembles to that of Irian Jaya. Vegetation on transition zone : Tropical Savanna vegetation on Nusa Tenggara, Mountain forest on Sulawesi and Mix Forest on Maluku. Mix forest on Maluku is the habitate of spices such as pala, cloves, and cinnamon, kenari, ebony, lontar.

The category is based on geological factor. Geologically, western of Indonesia archipelago was attached to Asia continent while on the eastern of Indonesia archipelago was attached to Australia continent. Therefore plants and animals from Asia continent has same typical as plants and animals on the western part of Indonesia. While plants and animals of the eastern part of Indonesia resembles to that of Australia.