Impact of invasive and native dominants on species richness and diversity of plant communities

Invasive alien plants are known to reduce the diversity of recipient communities. However, there is an ongoing debate on whether or not native dominant species have similar effects. To answer this question, we compared herbaceous plant communities in central Europe, 10 which were and nine region. We sampled 5–16 populations per species, selected reflect a gradient from low high cover studied include range typical habitats. reveal possible effect scale, vegetation 4 × m (large scale) 1 (small plots. All vascular their percentage covers recorded each plot. LMM regressions models used relate species’ richness community ANCOVAs test for differences between impacts vs. invasive dominants. On large 17 dominants (nine eight invasive) significantly reduced richness, seven (four three alien) decreased measured using Shannon H’ index. Reynoutria ×bohemica, Calamagrostis epigejos Phalaris arundinacea had strongest negative impact while Urtica dioica H’; results at small scale very similar. No significant detected with regard origin when all 19 included one model. Further, indirect ordination analysis (DCA) identify pairs that grow habitats and, thus, can be tested (native alien). This procedure yielded 27 total, as some occur more than type habitat could, therefore, coupled other group. At stronger cases (Calamagrostis epigejos, Cirsium oleraceum arundinacea) two (Aster novi-belgii agg. Rumex alpinus), making up 11.1% 7.4% total number examined, respectively. Only (Reynoutria alpinus) H’, four pairwise comparisons (14.8%). The but comparison. show both vegetation. conserve biodiversity, measures should adopted mitigate only also those dominants, spreading current landscape; would best achieved by promoting traditional management land-use.