Non-spatial sampling corresponds to the species rarefaction curve, which only
depends on the species abundance distribution and can thus be also calculated
from abundance data (see rare_curve
).
In contrast the species-accumulation curve starts from a focal individual and
only samples the nearest neighbours of the focal individual. The final
species accumulation curves is calculated as the mean over the accumulation
curves starting from all individuals.
In contrast to the rarefaction curve the accumulation curve is not only
influenced by the species abundance distribution, but also by the spatial
distribution of individuals.