Impact of troublesome expansive weed Rumex alpinus on species diversity of mountain pastures in Tatra National Park, Poland

Alpine dock (Rumex alpinus) is a native plant species in many European mountain ranges. It comes from moist brushwood and open tall herb communities, though it has invaded mountain pastures. This troublesome weed forms permanent monodominant stands characterised by low nature conservation and agricultural values. However, to the best of our knowledge, there are no studies assessing the impact of R. alpinus on invaded communities. Therefore, in this study we examined the potential effect of an R. alpinus on species richness, diversity and the composition of invaded vegetation in Tatra National Park, Poland. Invaded plots dominated by R. alpinus had, compared to uninvaded control plots, significantly reduced species richness, as well as low Shannon and Simpson diversity and Pielou evenness indices’ values; the species richness decline in the pairs of invaded-uninvaded plots was as much as 37.7%. Analysing changes in diversity from an increase in R. alpinus coverage revealed that Shannon, Simpson and Pielou’s diversity indices’ values did not considerably change up to 30% of R. alpinus coverage, but a further increase in R. alpinus coverage led to a steep decline in diversity. There was exception in a number of species per plot, which decreased steadily along with the increase of R. alpinus coverage. Multivariate analysis indicated a significant shift in the composition of invaded plots in relation to uninvaded plots, resulting from the shared increase of more shadow-tolerant and higher soil base-, nutrient- and moist-demanding species. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.2478/s11756-018-0148-9) contains supplementary material, which is available to authorized users.