Phytogeography Of India Pdf Download
In recent years, Nepal has proved to be rich in new taxa and particularly in the new species of Meconopsis, of Primula and of Pedicularis. Based on the published data, some deductions can be made about the phytogeography of Nepal. Information is gradually accumulating and becoming available as to the range of extension of the widely accepted East Himalayan elements and the West Himalyan elements. It is here in Nepal that the differing floras of the Eastern and Western Himalayas merge. The outstanding result is an expression of the eastern-ness of the vegetation of East Nepal, while in West Nepal the West Himalayan elements abound; thus botanically Nepal is of particular interest.
phytogeography of india pdf download
Phytogeography is often divided into two main branches: ecological phytogeography and historical phytogeography. The former investigates the role of current day biotic and abiotic interactions in influencing plant distributions; the latter are concerned with historical reconstruction of the origin, dispersal, and extinction of taxa.
The basic data elements of phytogeography are occurrence records (presence or absence of a species) with operational geographic units such as political units or geographical coordinates. These data are often used to construct phytogeographic provinces (floristic provinces) and elements.
The questions and approaches in phytogeography are largely shared with zoogeography, except zoogeography is concerned with animal distribution rather than plant distribution. The term phytogeography itself suggests a broad meaning. How the term is actually applied by practicing scientists is apparent in the way periodicals use the term. The American Journal of Botany, a monthly primary research journal, frequently publishes a section titled "Systematics, Phytogeography, and Evolution." Topics covered in the American Journal of Botany's "Systematics and Phytogeography" section include phylogeography, distribution of genetic variation and, historical biogeography, and general plant species distribution patterns. Biodiversity patterns are not heavily covered.A flora is the group of all plant species in a specific period of time or area, in which each species is independent in abundance and relationships to the other species. The group or the flora can be assembled in accordance with floral element, which are based on common features. A flora element can be a genetic element, in which the group of species share similar genetic information i.e. common evolutionary origin; a migration element has a common route of access into a habitat; a historical element is similar to each other in certain past events and an ecological element is grouped based on similar environmental factors. A population is the collection of all interacting individuals of a given species, in an area.
Phytogeography has a long history. One of the subjects earliest proponents was Prussian naturalist Alexander von Humboldt, who is often referred to as the "father of phytogeography". Von Humboldt advocated a quantitative approach to phytogeography that has characterized modern plant geography.
Research in plant geography has also been directed to understanding the patterns of adaptation of species to the environment. This is done chiefly by describing geographical patterns of trait/environment relationships. These patterns termed ecogeographical rules when applied to plants represent another area of phytogeography.
For more than half a century, The Botanical Review has been a leading international journal noted for its in-depth articles on a broad spectrum of botanical fields. Systematics, phytogeography, cladistics, evolution, physiology, ecology, morphology, paleobotany, and anatomy are but a few of the many subjects that have been covered. The Botanical Review draws together outstanding scientists in the field, synthesizes the current knowledge about a specific subject, and promotes the advancement of botany by indicating the gaps in our knowledge and providing new outlooks on the topic.
Four phytogeographical regions of Pakistan are recognised in an analysis of the phanerogams of Pakistan. Among the uniregionals, the most common element is Irano-Turanian (45.6%) followed by Sino-Japancse (10.6%), Saharo-Sindian (9.1%) and Indian (4.5%). Though in terms of the area, the Saharo-Sindian region occupies by far the biggest territory, the density of uniregional elements is lowest in this region. Overall there are only 6 endemic genera and an estimated 372 endemic species in Pakistan out of 4882 species. Highest numbers of uniregional endemics per unit area are met with in the Sino-Japanese region, followed by the Irano-Turanian and Saharo-Sindian region. Most of the endemics (78.22%) are confined to mountainous regions (c. 1200 m or above). Four areas, i.e. Sino-Japanese region of Kashmir (10.21% endemics), N Baluchistan (Irano-Turanian; 9.4% endemics) and Chitral (9.1% endemics), may be recognised as centres of radiation in Pakistan.
The present study on fossil plants comprising well-preserved leaf and fruit impressions from the Siwalik sediments exposed near Koilabas in western Nepal is the first detailed and systematic work. The floral assemblage recovered from these sediments is impoverished both in quality and quantity as constituted by 25 species belonging to 22 genera and 15 dicotyledonous families of angiosperms. This assemblage adds significant data to the Siwalik Palaeobotany. On the basis of present assemblage as well as already known data from the area, the palaeoclimate, palaeoecology, and phytogeography of the area during the Mio-Pliocene in the Himalayan foothills have been deduced. The significance of the physiognomic characters of the fossil leaves in relation to climate has also been discussed.