Functional regularity index (FRO for single traits)
Overall functional regularity index (OFRO for multiple traits)
FRO measures functional evenness using a single functional trait weighting by species abundace. It indicates how evenly-spaced species are in functional space.
OFRO is a modification of FRO when functional regularity for more than one traits needs to be estimated.
Authors
David Mouillot, W. H. Norman Mason, Olivier Dumay, and J. Bastow Wilson
Published in
Oecologia 141, 2005, pp 353-359.
Range
From 0 to 1
Weaknesses
To calcualte the index for multiple traits (OFRO) can be done either by calculating FRO separately for each trait, and taking the average of all these values, or by computing a principal components analysis and then using an eigenvalue to calcula FRO.
OFRO is not recommended with species richness is < 10.
Strengths
This index uses the real values of functional traits continous scales such as leaf size, weighted by abundance.
Functional regularity can be estimated as well for categorical traits (e.g. types of dispersal) and for functional groups.
FRO is independent of species and functional richness.
Main characteristics
This index is based on Bulla´s (1994) especies evennes index. Abundance weighted index.
FRO is orthogonal (independent) of functional richness.
R Package/software
fDiversity software
R Package description
Studies that used this index
References
Bulla L (1994) An index of evenness measure. Oikos 70:167–171.