Dear Natalie, it should be possible to use the betadisper-result to do this. However, a possibly faster way would be to calculate the area of the hull directly.
Here's an example: require(vegan) data(dune) data(dune.env) MDS <- cmdscale(vegdist(dune, method = 'bray')) plot(MDS, type = 'n') points(MDS, col = dune.env$Management, pch = 16) # area only for hull of NM take <- MDS[dune.env$Management == 'NM', ] hull <- chull(take) lines(take[c(hull, hull[1]), ]) require(splancs) areapl(take[c(hull, hull[1]), ]) HTH, Eduard On 29/07/15 19:26, Natalie wrote: > hi all > > I would like to calculate a dispersion index or similar from the > results of the vegan function betadisper. > i would like to know if there is a possibility to e.g. calculate the > volume of the community dispersion(area of the hull in the PCoA) from > the betadisper results. > common is to show the distance to the centroid.but I have the impression > the dispersion within communities are not that clear,especially if you > have similar variance. > The program primer v5 calculates a disperion index based on the > similarity percentage. > similarity percentage is not an option since it is mainly based on most > counted species. > > ideas and help are very much appreciated > cheers natalie > > _______________________________________________ > R-sig-ecology mailing list > R-sig-ecology@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-ecology > -- Eduard Szöcs Quantitative Landscape Ecology Institute for Environmental Sciences University Koblenz-Landau Tel. +49 6341 280 31552 http://www.uni-koblenz-landau.de/en/campus-landau/faculty7/environmental-sciences/landscape-ecology/Staff/eduardszoecs _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology