Data from: High-resolution and large-extent mapping of plant species richness using vegetation-plot databases

The recent increase in the availability of large vegetation-plot databases
has created unprecedented opportunities for analysing and explaining
patterns of fine-scale plant species richness across large areas and for
individual habitat types. Here we demonstrate how these data can be used
to (1) prepare country-wide high-resolution maps of species richness and
identify national diversity hotspots for grassland and forest vegetation;
(2) compare diversity patterns of all, native, alien and Red List species;
and (3) identify potential environmental drivers of these patterns. At the
same time we examine and quantify the stability of predicted
species-richness patterns with respect to the most common biases that are
inherent to large vegetation-plot databases. Vegetation-plot records were
obtained from the Czech National Phytosociological Database and the Random
Forest method was used to map fine-scale spatial diversity patterns of
all, native, alien and Red List vascular plant species, separately for
grasslands and forests across the Czech Republic. The stability of the
predicted species-richness patterns was tested using differently resampled
datasets in which we either reduced or increased local oversampling and
preferential sampling of more species-rich communities. Models for
grassland and forest vegetation explained 40–65% of variation in
fine-scale species richness. Spatial patterns of all and native species
richness differed considerably between grasslands and forests, whereas
alien and Red List species showed a higher congruence between these two
vegetation types. Patterns of modelled species richness were highly stable
with respect to all resampling strategies applied to the initial datasets.
We conclude that vegetation-plot databases are a valuable source of data
for high-resolution mapping of the plant species richness of different
vegetation types and species groups, because each of them can exhibit a
different diversity pattern. The resulting maps provide robust
representation of the spatial patterns of fine-scale species richness and
can be used both for testing scientific hypotheses about the controls of
diversity patterns and for conservation planning.