arc {BioFTF} | R Documentation |
This function provides the arc length of beta profile for each community. The arc length is a useful tool to establish a ranking among communities with intersecting profiles and the same number of species. It represents the length of a curve if it were rectified; it is a scalar measure extremely high in case of maximum dominance, whereas it decreases in case of high evenness. Unlike the classical indices, it considers each point of the domain corresponding to a different biodiversity value. For this reason, the arc length provides a ranking rule for communities with intersecting profiles, making possible to order them without the use of graphs. This is not possible with the classical indices.
arc(x,n)
x |
A data matrix with the abundance of the species (the rows are the communities and the columns indicate the species living in a community). The user can freely choose to use the absolute or relative frequencies. |
n |
The number of points of the domain [-1,1] that the user wants to consider in computing the functional tools. It is suggested to choose a number in the interval [3,10000] because a value of less than 3 has little sense; indeed, the major indices of biodiversity are the richness index, the index of Shannon and the index of Simpson (that we get for beta equal to -1, 0, +1, respectively). On the other hand, a value greater than 10000 is not very interesting because with a value of approximately 100 we already have a good approximation. The examples provided in this package always divide the domain into 20 intervals. The default value is n=20. |
Fabrizio Maturo, Francesca Fortuna, Tonio Di Battista
ENVIRONMENTAL MONITORING THROUGH FUNCTIONAL BIODIVERSITY TOOLS - T. Di Battista, F. Fortuna, F. Maturo - Ecological Indicators (2016) 60, 237-247 - online (2015). DOI: 10.1016/j.ecolind.2015.05.056.
PARAMETRIC FUNCTIONAL ANALYSIS OF VARIANCE FOR FISH BIODIVERSITY ASSESSMENT - T. Di Battista, F. Fortuna, F. Maturo - Journal of Environmental Informatics. Special issue of Marine and Freshwater Environmental Engineering and Management, Journal of Environmental Informatics. In press.
x=matrix(c(0.3,0.5,0.1,0.05,0.05,0.25,0.25,0.25,0.25,0,0.35,0.3,0.35,0,0),3,5) arc(x,20)