Which one of the two relations is more appropriate for the calculation of importance value index for a species?
IVI= Relative density + Relative frequency + Relative cover
(Reference: ECOLOGICAL STUDIES OF SOME ACACIA SPECIES GROWN IN
EGYPTIAN DESERTS)
or
IVI=Relative density + Relative frequency + Relative dominance (where dominance = Basal area x Density)
(Reference: An assessment and impact of three invasive species in
the Shivalik hills of Himachal Pradesh, India)
its depends on the vegetation type which you want to calculate IVI, first formula is better for grasslands and the second is for forests, but the first one is more popular.
It depends on what plant species you are working on. My research is all about fern ecology. To measure the IVI of each fern species I excluded the Relative Dominance. I need to do that since measuring the basal area of fern is time consuming. U might want to read this article.
If your study on herbaceous species, then IVI calculation is done by the farmula
IVI= Relative density + Relative frequency + Relative cover
kindly see the following reference
Mueller-Dombois and Ellenberg 1974
cover is best use for groundcover species whereas dominance best use for trees stratums for measuring IVI
Second formula is the more appropriate one.However you can also use Relative density+Relative abundance+Relative frequency= IVI
Both the formulae are appropriate, depending on the biome types. Yes the first one suits to deserts/grasslands, while the later for forest lands
Generally it depends on the type of vegetation which has to be analysed. The relative cover is used for IVI measurement in case of herbaceous vegetation while the relative dominance is used for IVI measurement in case of woody vegetation.
Both are correct but will depend what you actually determined in the field
The first one is more generalised and can be used for variety of vegetation
For understorey species Important Value Index (IVI) = Relative frequency + Relative density + Relative dominance is more appropriate
Relative dominance is more appropriate because in dominance basal area play important role in IVI measurement.
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