Biodiversity metrics
We calculated two response variables (relative species richness – alpha
diversity; beta-diversity - pairwise dissimilarity) for each of the four
analysed life forms, i.e., trees/shrubs, forbs, graminoids, and
climbers. Relative species richness was calculated following Burivalova
et al., (2014) as the total number of species in the burnt site divided
by the total number of species in the unburnt site. Consequently, values
of one represent situations where fire has no impact on species
richness, values less than one represent situations where fire reduces
species richness, and values greater than one represent situations where
fire increases species richness.
Species turnover (beta diversity) was calculated as Sørensen pairwise
dissimilarity index (Sørensen, 1948), which is widely used to measure
the spatial turnover for presence/absence data in ecology and is
independent of species richness (Koleff et al., 2003; Socolar et al.,
2016). A value of 0 means the composition of two communities is
identical, and a value of 1 means the two communities do not share any
species in common.