One of the Earth's six floristic kingdoms
Extent of the Paleotropical Kingdom
Gallery forest
in
Guinea
Savanna
in
Burkina Faso
Acacia erioloba
in the
Namib Desert
Pandanus utilis
Nepenthes villosa
The
Paleotropical Kingdom
(
Paleotropis
) is a
floristic kingdom
composed of the tropical areas of
Africa
,
Asia
and
Oceania
(excluding
Australia
and
New Zealand
), as proposed by
Ronald Good
and
Armen Takhtajan
. Part of its flora is inherited from the ancient supercontinent of
Gondwana
or exchanged later (e.g.
Piperaceae
with pantropical distribution and but few warm temperate representatives). These Gondwanan
lineages
are related to those in the
Neotropical Kingdom
, composed of the tropical areas of
Central
and
South America
. Flora from the Paleotropical Kingdom influenced the tropical flora of the
Australian Kingdom
. The kingdom is subdivided into five floristic subkingdoms according to Takhtajan (or three, according to Good) and about 13
floristic regions
. In this article the floristic subkingdoms and regions are given as delineated by Takhtajan.
Origin
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]
A distinct community of
vascular 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 of
podocarps
and
southern beech
. They were a type of flora characteristic of parts of
Gondwana
but were present in equivalent ecological areas.
Over millions of years, these type of vegetation present, covered much of the
tropics
of
Earth
. Many species are today
relicts
of a type of
vegetation
disappeared, which originally covered much of the mainland of Africa, Madagascar, India, South America, Antarctica,
Australia
, North America, Europe, and other lands when their
climate
were more
humid
and warm. Although warm
cloud 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 more
cold
-tolerant or
drought
-tolerant
sclerophyll
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 the
Carboniferous
and
Permian
, 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 the
South Pole
. In the
Triassic
and early
Jurassic
, Gondwana moved northward, warming the eastern margin.
New Caledonia separated from
Australia
and
New Zealand
during the breakup of the super-continent, separating from Australia at the end of the
Cretaceous
(66
mya
) 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 Atlantic
Macaronesia
islands and Pacific
Taiwan
,
Hainan
,
Jeju
,
Shikoku
,
Ky?sh?
, and
Ry?ky? 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 limited
seed dispersal
mobility away from the parent plant and consequently rely upon a variety of
dispersal vectors
to transport their propagules, including both
abiotic
and
biotic
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
in
Ericaceae
, or
Wollemia
in the family
Araucariaceae
, was known only from fossil remains before the discovery of the living species in 1994 in a temperate
rainforest
wilderness area of the
Wollemi National Park
in
New South Wales
, in a remote series of narrow, steep-sided sandstone
gorges
near
Lithgow
.
Fossils dating from before the
Pleistocene
glaciations
show that species of
Laurus
were formerly distributed more widely around the Mediterranean and
North Africa
, isolated gave rise to
Laurus azorica
in Azores Islands,
Laurus nobilis
in mainland and
Laurus novocanariensis
in Canary Islands.
Flora
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The paleotropical
flora
is characterized by about 40
endemic
plant
families
, the most famous being
Nepenthaceae
,
Musaceae
,
Pandanaceae
and
Flagellariaceae
,
[2]
but including also
Matoniaceae
,
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
) and
Lowiaceae
.
[3]
Subdivisions
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]
African Subkingdom
[
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]
10 endemic families (incl.
Dioncophyllaceae
,
Pentadiplandraceae
,
Scytopetalaceae
,
Medusandraceae
,
Dirachmaceae
,
Kirkiaceae
), many endemic genera.
- Guineo-Congolian Province
- Usambara-Zululand Region
- Sudano-Zambezian Region
(including tropical Asia west of the
Gulf of Khambhat
)
- Karoo-Namib Region
- St. Helena and Ascension Region
Madagascan Subkingdom
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]
9 endemic families, more than 450 endemic genera, about 80% endemic species. It ceased to be influenced by the African flora in the
Cretaceous
, but underwent heavy influence of the Indian Region's flora.
- Madagascan Region
Indo-Malesian Subkingdom
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]
11 endemic families (incl.
Degeneriaceae
,
Barclayaceae
,
Mastixiaceae
) and many endemic genera
- Indian Region
- Indochinese Region
- Malesian Region
- Fijian Region
Polynesian Subkingdom
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]
No endemic families, many endemic genera. The flora is mostly derivative from that of the Indo-Malesian Subkingdom.
- Polynesian Region
- Hawaiian Region
Neocaledonian Subkingdom
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]
New Caledonia
lies on the southernmost edge of the tropical zone, near the
Tropic 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. The
biodiversity of New Caledonia
include several endemic families (incl.
Amborellaceae
,
Strasburgeriaceae
) and more than 130 endemic genera (incl.
Exospermum
and
Zygogynum
). The flora is partially shared with the Indo-Malesian Subkingdom and the
Australian Kingdom
.
- Neocaledonian Region
See also
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]
References
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]