  To model discriminative, i.e. competition induced, self-thinning in even-aged
forest stands a concept has been explored that discriminative mortality alters
spatial arrangement of trees which in turn alters the mortality. Function of
density was suggested to be a balance of initial density minus mortality that
was dependent on initial spatial arrangement and mean horizontal size in the
forest stand. Assuming initial spatial arrangement to be aggregation and
performing normalizations gave the self-thinning function depending on only two
parameters, initial stem density and maximal horizontal size (represented by
stem diameter). Normalizations included integral of probability of trees to
collide to be unity and stem density at maximal size to be zero. The
self-thinning function obtained has been shown to successfully capture
non-linear self-thinning dynamics in Douglas-fir long-term experiments in which
competition-induced mortality prevailed.
