ThePaleotropical kingdom (Paleotropis) is afloristic kingdom composed of the tropical areas ofAfrica,Asia andOceania (excludingAustralia andNew Zealand), as proposed byRonald Good andArmen Takhtajan. Part of its flora is inherited from the ancient supercontinent ofGondwana or exchanged later (e.g.Piperaceae with pantropical distribution and but few warm temperate representatives). These Gondwananlineages are related to those in theNeotropical kingdom, composed of the tropical areas ofCentral andSouth America. Flora from the Paleotropical kingdom influenced the tropical flora of theAustralian Kingdom. The kingdom is subdivided into five floristic subkingdoms according to Takhtajan (or three, according to Good) and about 13floristic regions. In this article the floristic subkingdoms and regions are given as delineated by Takhtajan.
A distinct community ofvascular plants evolved millions of years ago, and are now found on several separate areas.Millions of years ago, the warmer and wetter areas supported a tropical adapted flora, including forests ofpodocarps andsouthern beech. They were a type of flora characteristic of parts ofGondwana but were present in equivalent ecological areas.
Over millions of years, these types of vegetation covered much of thetropics ofEarth. Many species are todayrelicts of a type ofvegetation disappeared, which originally covered much of the mainland of Africa, Madagascar, India, South America, Antarctica,Australia, North America, Europe, and other lands when theirclimate were morehumid and warm. Although warmcloud forests disappeared during the glaciations, they re-colonized large areas every time the weather was favorable again. Most of the cloud forests are believed to have retreated and advanced during successive geological eras, and their species adapted to warm and wet gradually retreated and advanced, replaced by morecold-tolerant ordrought-tolerantsclerophyll plant communities. Many of the existing species became extinct because they could not cross the barriers posed by new oceans, mountains and deserts, but others found refuge as species relict in coastal areas and Islands.
In theCarboniferous andPermian, New Zealand and New Caledonia were on the periphery of Gondwana, which included Africa, South America, Antarctica, India, New Zealand and Australia. Paleomagnetic data locate New Caledonia originally near theSouth Pole. In theTriassic and earlyJurassic, Gondwana moved northward, warming the eastern margin.New Caledonia separated fromAustralia andNew Zealand during the breakup of the super-continent, separating from Australia at the end of theCretaceous (66mya) and probably completing its separation from New Zealand in the mid-Miocene.
The ecological requirements of many of the species, are those of the laurel forest and like most of their counterparts laurifolia in the world, they are vigorous species with a great ability to populate the habitat that is conducive.The geographical isolation and special edaphic conditions helped to preserve it too.
Many members of the late Cretaceous–early Tertiary Gondwanan flora survived in islands and Coastal area's equable climate but were eliminated in mainland due to increasingly dry conditions.[1] When the large landmasses became drier and with a harsher climate, this type of forest was reduced to those boundaries areas.Tasmania, Chile, New Zealand and New Caledonia share related species extinct in Australia mainland. The same case occurs in the AtlanticMacaronesia islands and PacificTaiwan,Hainan,Jeju,Shikoku,Kyūshū, andRyūkyū Islands. Although some remnants of archaic rich flora still persisted in their coastal mountains and shelter sites, their biodiversity were reduced. The location of Islands in the oceans moderated these climatic fluctuations, and maintained the relatively humid and mild climate which has allowed these communities to persist to the present day.
Plants have limitedseed dispersal mobility away from the parent plant and consequently rely upon a variety ofdispersal vectors to transport their propagules, including bothabiotic andbiotic vectors. Seeds can be dispersed away from the parent plant individually or collectively, as well as dispersed in both space and time. Tertiary vegetal species isolated on islands have led to vicariant species; genera and families extinct in the rest of the world have been preserved as island endemics.
For example, genera,Archeria inEricaceae, orWollemia in the familyAraucariaceae, was known only from fossil remains before the discovery of the living species in 1994 in a temperaterainforest wilderness area of theWollemi National Park inNew South Wales, in a remote series of narrow, steep-sided sandstonegorges nearLithgow.
Fossils dating from before thePleistoceneglaciations show that species ofLaurus were formerly distributed more widely around the Mediterranean andNorth Africa, isolated gave rise toLaurus azorica in Azores Islands,Laurus nobilis in mainland andLaurus novocanariensis in Canary Islands.
The paleotropicalflora is characterized by about 40endemic plantfamilies, the most famous beingNepenthaceae,Musaceae,Pandanaceae andFlagellariaceae,[2] but including alsoMatoniaceae,Dipteridaceae,Stangeriaceae,Welwitschiaceae,Degeneriaceae,Rafflesiaceae,Didiereaceae,Didymelaceae,Ancistrocladaceae,Dioncophyllaceae, Scytopetalaceae (Scytopetalum),Medusagynaceae, Scyphostegiaceae (Scyphostegia),Sarcolaenaceae,Sphaerosepalaceae,Huaceae,Pandaceae,Crypteroniaceae,Duabangaceae, Strephonemataceae (Strephonema),Psiloxylaceae,Dirachmaceae,Phellinaceae,Lophopyxidaceae,Salvadoraceae,Medusandraceae, Mastixiaceae (Mastixia), Hoplestigmataceae (Hoplestigma) andLowiaceae.[3]
10 endemic families (incl.Dioncophyllaceae,Pentadiplandraceae,Scytopetalaceae,Medusandraceae,Dirachmaceae,Kirkiaceae), many endemic genera.
9 endemic families, more than 450 endemic genera, about 80% endemic species. It ceased to be influenced by the African flora in theCretaceous, but underwent heavy influence of the Indian region's flora.
11 endemic families (incl.Degeneriaceae,Barclayaceae,Mastixiaceae) and many endemic genera
No endemic families, many endemic genera. The flora is mostly derivative from that of the Indo-Malesian subkingdom.
New Caledonia lies on the southernmost edge of the tropical zone, near theTropic of Capricorn. This flora originated on the supercontinent Gondwana, and persist in current day New Guinea, Australia, New Zealand, New Caledonia and South America. This flora is fossil in Antarctica. Thebiodiversity of New Caledonia include several endemic families (incl.Amborellaceae,Strasburgeriaceae) and more than 130 endemic genera (incl.Exospermum andZygogynum). The flora is partially shared with the Indo-Malesian subkingdom and theAustralian Kingdom.