Reciprocal scaling of species and plot records. Each point represents a plot. Ellipses represent respective species habitat amplitudes (niche breadth) and deviances (niche position) compared to a theoretical species having a uniform distribution derived on the sampling (central ellipse). The centre of the ellipse is given by the mean of ordination scores, and axes of the ellipse are related to the variance of ordination scores. The figure gives an example of four contrasted species, each of the 152 species were assessed in this way. Both rare (Frequency < 5%) and common (Frequency > 5%) species can present a full range of responses from wide (generalist) to narrow (specialist) niche breadth.
Fried et al. BMC Ecology 2010 10:20 doi:10.1186/1472-6785-10-20