<P> The concept "vegetation type" is more ambiguous . For some authors, it includes, besides physiognomy, floristic and habitat aspects . Furthermore, the phytosociological approach in the study of vegetation relies upon a fundamental unit, the plant association, which is defined upon flora . </P> <P> An influential, clear and simple classification scheme for types of vegetation was produced by Wagner & von Sydow (1888). Other important works with a physiognomic approach includes Grisebach (1872), Warming (1895, 1909), Schimper (1898), Tansley and Chipp (1926), Rübel (1930), Burtt Davy (1938), Beard (1944, 1955), André Aubréville (1956, 1957), Trochain (1955, 1957), Küchler (1967), Ellenberg and Mueller - Dombois (1967) (see vegetation classification). </P> <Table> <Tr> <Td> </Td> </Tr> </Table> <P> There are many approaches for the classification of vegetation (physiognomy, flora, ecology, etc .). Much of the work on vegetation classification comes from European and North American ecologists, and they have fundamentally different approaches . In North America, vegetation types are based on a combination of the following criteria: climate pattern, plant habit, phenology and / or growth form, and dominant species . In the current US standard (adopted by the Federal Geographic Data Committee (FGDC), and originally developed by UNESCO and The Nature Conservancy), the classification is hierarchical and incorporates the non-floristic criteria into the upper (most general) five levels and limited floristic criteria only into the lower (most specific) two levels . In Europe, classification often relies much more heavily, sometimes entirely, on floristic (species) composition alone, without explicit reference to climate, phenology or growth forms . It often emphasizes indicator or diagnostic species which may distinguish one classification from another . </P>

Explain about types of natural vegetation found in india