Use of Important Value Index (IVI) is very important in research. Some researches have used IVI as the summation of RD+RF+RDo( total basal area of spp A/total basal area of all spp *100)
where,
RD= RELATIVE DENSITY
RF=RELATIVE FREQUENCY
RDo=RELATIVE DOMINANCE
for tree, shrubs and herb spp and some researchers have used IVI= RD+RF+RCo(Relative cover). Calculating the basal area of the herb spp even in 1*1m plot is time consuming and questionable. Is there any other method to calculate the relative dominace of herb spp without measuring the basal area?
Yes, you can calculate the relative dominance on above-ground biomass basis.
Arvind Singh can you please, provide me any relevent document if available?
IVI = Relative frequency + Relative density + Relative dominance
Use a the formula recommended in Mandal and Josh (2014)
Article Analysis of vegetation dynamics and Phytodiversity from Thre...
IVI = Relative density + Relative dominance + Relative frequency
Where,
dominance = basal area per ha,
density = number of individuals per ha, and
frequency = occurrence of certain species in respective sample plots
Similarly,
Relative density = (No of individuals of the species)/total number of individuals of all species) *100
Relative dominance = (Total basal area of the species)/ (Total basal area of all species)*100
Relative frequency= (Percent of the sample plots occupied by the species)/ (Percent of the occurrence of all species) *100
Each of these values is expressed as a percentage and ranges from 0% to 100%. The IVI is the sum of these three components and can range from 0 to 300 (Adapted from Curtis & McIntosh, 1951). We can discuss more if you wish. Good luck Bijaya.
Kishor Prasad Bhatta tq daaju for your response. However im confused with the technique to measure the basal area of the individual herb spp
A review of about 40 importance indexes is published. See attached pdf (The importance of a species in a biocoenosis, a class of biocoenoses, and a region: a review of combined indexes. Biology Bulletin, 2021: 48 (3), pp 379–393).
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