Malesia is a biogeographical region straddling the Equator and the boundaries of the Indomalayan and Australasian realms, and also a phytogeographical floristic region in the Paleotropical Kingdom. The original definition by the World Geographical Scheme for Recording Plant Distributions included Papuasia, but this was split off in its 2001 version.
Malesia was first identified as a floristic region that included the Malay Peninsula, the Malay Archipelago, New Guinea, and the Bismarck Archipelago, [1] based on a shared tropical flora derived mostly from Asia but also with numerous elements of the Antarctic flora, including many species in the southern conifer families Podocarpaceae and Araucariaceae. The floristic region overlaps four distinct mammalian faunal regions.
The first edition of the World Geographical Scheme for Recording Plant Distributions (WGSRPD) used this definition, but in the second edition of 2001, New Guinea and the Bismarck Archipelago were removed from Malesia and were united with the Solomon Islands, previously placed in the WGSRPD's Southwestern Pacific region, being placed into a new region, Papuasia. [2]
The western part of Malesia, which includes the Malay Peninsula and the islands of Sumatra, Java, Bali, and Borneo, shares the large mammal fauna of Asia and is known as Sundaland. These islands are on Asia's relatively shallow continental shelf, and were linked to Asia during the ice ages, when sea levels were lower. The eastern edge of Sundaland is the Wallace line, named after Alfred Russel Wallace, the nineteenth-century British naturalist who noted the difference in fauna between islands on either side of the line.
Dipterocarps are predominant trees in the lowland forests of Sundaland. [3] Sundaland has the greatest diversity of Dipterocarp species, with 10 to 14 native genera and approximately 450 native species, including approximately 267 species on Borneo, 155 on the Malay Peninsula, and 106 on Sumatra. [4]
Most of the Philippines were never connected to the Asian mainland, and have a largely Asian-derived flora, and a distinct mammalian fauna.
The Philippines have approximately 50 species of Dipterocarps in 11 genera. [4]
The islands between Sundaland and New Guinea, called Wallacea, were never linked to the neighboring continents, and have a flora and fauna that include Indomalayan and Australasian elements.
Dipterocarps, which are dominant in Sundaland, are less common in Wallacea, with only 13 species in 4 genera. [4]
Together with the Solomon Islands, New Guinea and the Bismarck Archipelago are placed in Papuasia rather than Malesia in the second version of the WGSRPD. The eastern end of the earlier definition of Malesia, which includes New Guinea and the Aru Islands of eastern Indonesia, is linked to Australia by a shallow continental shelf, and shares many marsupial mammal and bird taxa with Australia. New Guinea also has many additional elements of the Antarctic flora, including southern beech ( Nothofagus ) and eucalypts. New Guinea has the highest mountains in Malesia and Papuasia, and vegetation ranges from tropical lowland forest to tundra.
Major contributions to rainforest assembly have come from floristic elements which were carried on the Indian Plate and montane elements which have come from the Australian Plate (Sahul). The Sahul component is now understood to include substantial two-way exchanges with Sunda inclusive of lowland taxa. Evidence for the relative contributions of the great Asiatic floristic interchanges (GAFIs) with India and Sahul, respectively, to the flora of Malesia comes from contemporary lineage distributions, the fossil record, time-calibrated phylogenies, functional traits, and the spatial structure of genetic diversity. Functional trait and biome conservatism are noted features of montane austral lineages from Sahul (e.g., diverse Podocarpaceae), whereas the abundance and diversity of lowland lineages, including groups such as Syzygium (Myrtaceae) and the Asian dipterocarps (Dipterocarpoideae), reflect a less well understood combination of dispersal, ecology, and adaptive radiations. Thus, Malesian rainforest assembly has been shaped by sharply contrasting evolutionary origins and biogeographic histories. [5]
The Malay Peninsula is a peninsula in Mainland Southeast Asia. The landmass runs approximately north–south, and at its terminus, it is the southernmost point of the Asian continental mainland. The area contains Peninsular Malaysia, Southern Thailand, and the southernmost tip of Myanmar (Kawthaung). The island country of Singapore also has historical and cultural ties with the region. The indigenous people of the peninsula are Orang Asli and Malays, an Austronesian people.
The Indomalayan realm is one of the eight biogeographic realms. It extends across most of South and Southeast Asia and into the southern parts of East Asia.
The Australasian realm is a biogeographic realm that is coincident with, but not the same as, the geographical region of Australasia. The realm includes Australia, the island of New Guinea, and the eastern part of the Indonesian archipelago, including the island of Sulawesi, the Moluccas, and the islands of Lombok, Sumbawa, Sumba, Flores, and Timor, often known as the Lesser Sundas.
The Solomon Islands rain forests are a terrestrial ecoregion covering most of the Solomon Islands archipelago.
Sundaland is a biogeographical region of South-eastern Asia corresponding to a larger landmass that was exposed throughout the last 2.6 million years during periods when sea levels were lower. It includes Bali, Borneo, Java, and Sumatra in Indonesia, and their surrounding small islands, as well as the Malay Peninsula on the Asian mainland.
Wallacea is a biogeographical designation for a group of mainly Indonesian islands separated by deep-water straits from the Asian and Australian continental shelves. Wallacea includes Sulawesi, the largest island in the group, as well as Lombok, Sumbawa, Flores, Sumba, Timor, Halmahera, Buru, Seram, and many smaller islands. The islands of Wallacea lie between the Sunda Shelf to the west, and the Sahul Shelf including Australia and New Guinea to the south and east. The total land area of Wallacea is 347,000 km2 (134,000 sq mi).
The Philippine archipelago is one of the world's great reservoirs of biodiversity and endemism. The archipelago includes over 7000 islands, and a total land area of 300,780 km².
Near Oceania is the part of Oceania settled 35,000 years ago, comprising Australia, New Guinea, and north-western Island Melanesia: the Bismarck Archipelago and the Solomon Islands.
Geologically, the Sunda Shelf is a south-eastern extension of the continental shelf of Mainland Southeast Asia. Major landmasses on the shelf include Bali, Borneo, Java, Madura, and Sumatra, as well as their surrounding smaller islands. It covers an area of approximately 1.85 million km2. Sea depths over the shelf rarely exceed 50 metres and extensive areas are less than 20 metres resulting in strong bottom friction and strong tidal friction. Steep undersea gradients separate the Sunda Shelf from the Philippines, Sulawesi, and the Lesser Sunda Islands.
Dysoxylum is a flowering plant genus of trees and shrubs from the mahogany family, Meliaceae.
Geologically, the Sahul Shelf is a part of the continental shelf of the Australian continent, lying off the northwest coast of mainland Australia.
The fauna of Indonesia is characterised by high levels of biodiversity and endemicity due to its distribution over a vast tropical archipelago. Indonesia divides into two ecological regions; western Indonesia which is more influenced by Asian fauna, and the east which is more influenced by Australasian species.
The flora consists of many unique varieties of tropical plants. Blessed with a tropical climate and roughly 17,000 islands, Indonesia is the nation with the second highest biodiversity in the world. The flora of Ind reflects an intermingling of Asian, Australian and unique, Indonesian lineages. This is due to the geography of Indonesia, located between the aforementioned continents. The archipelago consists of a variety of regions, from the tropical rain forests of the northern lowlands and the seasonal forests of the southern lowlands through the hill and mountain vegetation, to subalpine shrub vegetation. With the second longest coastline in the world, Indonesia also has many swamps and other varieties of coastal vegetation. Combined, these all give rise to a huge floral biodiversity. There are about 28,000 species of flowering plants documented in Indonesia, including 2500 orchids, 122 species of bamboo, over 350 species of rattan and 400 species of Dipterocarpus, including ebony, sandalwood and teakwood. Indonesia is also home to some unusual species of carnivorous plants. One exceptional species is known as Rafflesia arnoldi, named after Sir Thomas Stamford Raffles and Dr. Thomas Arnold, who discovered the flower in the depths of Bengkulu, southwest Sumatra. This parasitic plant has the largest flower of any plant, does not produce leaves and grows only on one species of liana on the rainforest floor. Another unusual plant is Amorphophallus titanum from Sumatra. Numerous species of insect trapping pitcher plants can also be found in Borneo, Sumatra, and other islands of the Indonesian archipelago. There are a staggering 6000 traditional medicinal plants used as Jamu.,
The World Geographical Scheme for Recording Plant Distributions (WGSRPD) is a biogeographical system developed by the international Biodiversity Information Standards (TDWG) organization, formerly the International Working Group on Taxonomic Databases. The WGSRPD standards, like other standards for data fields in botanical databases, were developed to promote "the wider and more effective dissemination of information about the world's heritage of biological organisms for the benefit of the world at large". The system provides clear definitions and codes for recording plant distributions at four scales or levels, from "botanical continents" down to parts of large countries. The codes may be referred to as TDWG geographical codes. Current users of the system include the International Union for Conservation of Nature (IUCN), the Germplasm Resources Information Network (GRIN), and Plants of the World Online (POWO).
New Guinea is the world's second-largest island, with an area of 785,753 km2 (303,381 sq mi). Located in Melanesia in the southwestern Pacific Ocean, the island is separated from Australia by the 150-kilometre wide Torres Strait, though both landmasses lie on the same continental shelf, and were united during episodes of low sea level in the Pleistocene glaciations as the combined landmass of Sahul. Numerous smaller islands are located to the west and east. The island's name was given by Spanish explorer Yñigo Ortiz de Retez during his maritime expedition of 1545 due to the resemblance of the indigenous peoples of the island to those in the African region of Guinea.
New Guinea, lying within the tropics and with extensive mountain areas, comprises a wide range of ecoregions. These include rainforests, grasslands and mangrove.
The Tenasserim–South Thailand semi-evergreen rain forests are a tropical moist forest ecoregion in Southeast Asia. The ecoregion extends north–south along the Kra Isthmus. It includes lowland forests along the coasts, and montane forests in the Tenasserim Hills and Bilauktaung range, which form the mountainous spine of the isthmus.
The Lesser Sunda Islands, also known as Nusa Tenggara Islands, are an archipelago in Maritime Southeast Asia, most of the Lesser Sunda Islands are located within the Wallacea region, except for the Bali province which is west of the Wallace Line and is within the Sunda Shelf. Together with the Greater Sunda Islands to the west they make up the Sunda Islands. The islands are part of a volcanic arc, the Sunda Arc, formed by subduction along the Sunda Trench in the Java Sea. Slightly over 20 million people live on the islands. Etymologically, Nusa Tenggara means "Southeast Islands" from the words of nusa which means 'island' from Old Javanese language and tenggara means 'southeast'.
The Sulawesi lowland rain forests is a tropical moist forest ecoregion in Indonesia. The ecoregion includes the lowlands of Sulawesi and neighboring islands.
Media related to Indomalaya at Wikimedia Commons Media related to Animals of Malesia at Wikimedia Commons