Professor Armen Takhtajan, a giant among botanists, has spent a lifetime in the service of his science and of humanity. As a thoroughgoing. Floristic Regions of the World has 2 ratings and 0 reviews: Published September 4th by University of California Press, pages, Hardcover. Loading data.. Open Bottom Panel. Go to previous Content Download this Content Share this Content Add This Content to Favorites Go to next Content. ← →.
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Biogeographic links with neighbouring regions. An introduction to the floristic regions of the World. The vegetation types of the World can be categorised into units that reflect internal consistence and external links. Biogeographers term these phytogeographic ‘taxa’ as phytochoria singular phytochorion. As patterns in vegetation change are rarely clear cut it is difficult to place exact geographic boundaries around phytochoria.
Areas of overlap are common where transitional vegetation types are seen, these are sometimes termed vegetation tension zones. Several systems of phytochoria have been proposed, most organized hierarchically. In zoology there are different systems of faunistic classifications, some have similarities with the phytochoria, others have significant differences.
Some systems now take into account both plant and animal species. Ronald Good proposed a system of six floristic Kingdoms Australian, Antarctic, Boreal, Neotropical, Paleotropical, and South African as the largest natural units for flowering plants.
The Kingdoms takgtajan subdivided into Subkingdoms, Provinces and Regoins. The Paleotropical Kingdom was first divided into 3 Subkingdoms, whereas each of the other five kingdoms were subdivided directly into Provinces totalling 37 Provinces.
Criteria for phytochorion ranks following Takhtajan, Characterised by high levels of endemic families, sub-families and tribes and very high levels of species endemism.
Floristic Regions of the World by Armen Takhtajan
Characterised by high levels of generic endemism but not usually families unless mono-generic and very high levels of species endemism. Characterised by high levels of species endemism but not usually genera unless monospecific and assemblages of corrulated families. Nepal has a complex biogeography due to its past geological history and its presence at the cross roads of two bio-geographic realms the Palaearctic and the Indo-Malayan realms, Udvardyand two major phytogeographical Kingdoms: Furthermore, Nepal lies at a transition zone between the flora of the Western Himalaya with many Western Asiatic and Mediterranean elements — the Irano-Turanian photochorion and the Eastern Himalaya with many Sino-Japanese elements — the Eastern Asiatic phytochorion.
Adding variety are also plants from arid highlands of the Tibetan Plateau Central Asian elements in the north, and in the southern lowland plains Terai plants from the Indo-Gangetic elements Indochinese and Indomalayan regions are found representing widespread species from the humid tropics that extend deep into SE Asia.
Understanding flotistic distribution of plants within the Himalaya thus requires an examination of both the floristic regions found in the area see below and the geological history of the Himalaya see the Himalaya page. Takhtajan recognised six Kingdoms: Takhtajan further divided his Kingdoms into eight Subkingdoms, 35 worlv Regions, and Provinces.
Below regionns Province level Takhtajan sometimes recognised Districts. Region numbers in the above map refer to the following paragraphs. Characterised by high levels of infra-specific endemism. Holarctic Kingdom [palearctic] Boreal subkingdom: East asiatic [sino-japanese] region 2: From the Kali Gandaki Valley ca. Characterised by monsoon climate, and contains a number of endemic and near endemic genera and many endemic species.
Rhododendron species are well represented with 30 in Nepal and 45 in Bhutan. Other characterisitc species include: Abies densa, Pinus bhutanica, Larix griffithiana, Cupressus corneyana, and Rheum nobile. This province is one of the youngest floras in the region, formed by dispersal from mountains of China, Burma, Assam.
Tethyan subkingdom [ancient mediterranean]: Irano-turanian region 8 Tibetan Province. Primarily the Tibetan Plateau, but degions encompasses some or all of the Pamirs in far west Himalaya. A very young flora which is not species rich probably less than species.
Affinities largely lie with the Irano-Turanian and Central Asiatic regions. Central parts of the plateau are dominated by halophytes, whereas the mountainous borders are typically inhabited by cushion-forming plants, hemicryptophytes and geophytes.
Southern areas between the Transhimalaya and Himalaya are dominated by open communities ‘gravel deserts’ of dwarf perennials. Characterised by monsoon climate. There are strong florisic links with the Iranian highlands and the Mediterranean flora region 7: Arbutus undeo and Myrtus takhtajsn.
This is a transitional zone between the ancient Mediterranean Tethyan and E Asiatic floras, but takhtaajan Irano-Turanean elements dominate. Cedrus deodara, Abies pindrow, Picea smithiana and Cupressus torulosa.
Rhododendron species diversity is not as great as further east, but includes R. Pelaotropical kingdom African subkingdom: Covers a huge area from the Atlantic coasts of southern Mauritania, south to the Cape region, northeastern and eastern tropical Africa, tropical parts of the Arabian Peninsula including Socotratropical deserts of Iran, Pakistan and NW India. The main vegetation types are open woodland, savanna and grassland characterised by genera such as Combretum,Terminalia, Brachystegia and Hyparrhenia.
Within this region the Sindian provice is the area closest to the Himalaya. Upper gangetic plain province: Aravalli Hills and Yamuna River in the west to the Koshi River E Nepal in the east, including the terai areas up to m foothills of the Siwaliks and the entire lowlands of the upper courses of the Ganges. This province hasgenerally lacks endemics and forests have largely been destroyed. Sal Shorea robusta dominates where forest remains, and there are considerable areas florishic halophytic vegetation.
In many places there are scattered Acacia trees, and on the most saline soils Salvadora persica is almost the only tree that succeeds. Koshi River E Nepal in the east to Arakan in Burma Myanmar in the west, including the terai areas up to m foothills of the Siwaliks and the lower courses of the Ganges and Brahmaputra. A very rich flora of luxuriant vegetation due to the high rainfall, tropical semi-evergreen forest predominates.
There are a few endemic genera and many endemic species.
The eastern borders of this region include the southeastern and eastern border areas of Bangladesh and adjoining regions of India. The region includes over endemic genera, but only one endemic family Plagiopteraceae. The number of endemic species is hugh, and the natural vegetation is generally better preserved and considerably richer than the Indian Region.
In contrast with the Indian Region the Indochinese Region is characterised by montane forests of evergreen species of Lithocarpus, Castanopsis and Quercus.
The Geography of the Flowering Plants. Academy of Sciences of the U. Floristic Regions of the World. University of California Press, Berkeley.
Wu, Zheng-yi and Wu, Sugong, China Higher Education Press, Beijing. Aesculus indica, Cedrus deodara are predominantly found in the west, Castanopsis hystrix and Larix griffithiana are predominantly eastern and central Nepal.