2.2.2.7. Plant species richness. Plant species richness is a measure of
the number of different kinds of plants present in a particular area;
the more species present in a sample, the ‘richer’ the sample according
to Simpson (1949). Simpson’s diversity index, D ¼P(n/N)2
was used, where n is the total number of organisms of a particular
species and N is the total number of organisms of all species. The
value of D ranges between 0 and 1, with 0 representing infinite
diversity and 1 no diversity. Thus, the larger the value of D, the
lower the diversity. Generally, plant species diversity was calculated
for each quadrate and these data were summed for each transect.