Impacts of native and alien plant dominants at different spatial scales

Plant invasion science has made a substantial progress in documenting the impacts of aliens, but comparisons with the impacts of native dominants are still rare. Further, the impacts on larger spatial scales remain poorly understood. We recorded the impacts of 10 native and nine invasive dominant plants in the Czech Republic on species richness and Shannon diversity by comparing communities with high vs. low cover of the dominant species. To estimate the impacts at the (i) population level and (ii) between-population level, we compared the Jaccard dissimilarity, nestedness and turnover of high- and low-dominance plots. Further, we calculated the Jaccard dissimilarity, nestedness and turnover between the high- and low-dominance plots within each population to express the impacts on species composition. We tested whether (i) native and invasive dominants affect the population- and between population levels of diversity by making the vegetation more homogenous; (ii) whether these effects differ between the native and alien dominants; and (iii) whether the impacts at different spatial levels are related. At the population level, high-dominance plots (with both native and alien dominants) showed higher nestedness and lower turnover compared to the low-dominance plots. Further, all plots with native dominants, both with high- and low dominance, showed higher similarity but lower nestedness than plots with alien dominants. Most importantly, high-dominance plots with native dominants were more similar to each other but showed marginally significantly lower nestedness compared to high-dominance plots with alien dominants. At the between-population level, high-dominance plots with native dominants showed a marginally significantly lower turnover compared to high-dominance plots with alien dominants. The differences in Jaccard dissimilarity, nestedness and turnover between the low- and high-dominance plots at the population level showed strong positive relations to low- and high-dominance differences at the between-populations level. Further, compositional impacts, expressed as the dissimilarity between high- vs. low-dominance plots, positively related to the plot-level impacts on Shannon diversity. Our results show that (i) both native and invasive dominants tend to reduce the diversity over larger areas and that the effect of native dominants may be even stronger, and (ii) the effects on plot-level richness and diversity cannot be easily extrapolated to larger scales but the impacts at the population- and between-populations levels are positively related

Flora and vegetation of selected wet and fen grasslands near Havlíčkův Brod

The research was conducted in the growing season 2015 in selected wet and peaty meadows near Havlíčkův Brod (Bohemian-Moravian highlands). Phytosociological classification was carried out using the formalized Cocktail method, which assigns relevés by formal definitions, and method of assigning according to similarity of species composition (FPFI index). Nine vegetation groups were delimitated: seven at association and two at alliance level. Wet meadow of the association Angelico sylvestris-Cirsietum palustris is the most common community. Wet meadows of the associations Scirpetum sylvaticae and Lysimachio vulgaris- Filipenduletum ulmariae (both Calthion alliance) regularly occur. The stands of the associations Poo-Trisetetum flavescentis (Arrhenatherion alliance) and Poo trivialis- Alopecuretum pratensis (Deschampsion alliance) was documented at the drier edges of the localities. Thirteen species listed in the Red list of the Czech Republic were found. Dactylorhiza majalis, Tephroseris crispa and Valeriana dioica were the most abundant. Carex hartmanii, Carex paniculata, Eleocharis mammilata subsp. mamillata, Epilobium palustre, Pedicularis sylvatica, Potamogeton lucens, Comarum palustre, Scorzonera humilis, Sparganium erectum and Trifolium spadiceum occur rarely. Some localities (Bartoušov, Čistá, Dlouhá Ves-Pod silnicí, Mozerov a Skorkov) are suitable for statute significant landscape element for the occurence of these endangered species

Changes in assemblages of native and alien plants in perennial plantations: prairie species stabilize the community composition

Ornamental plantations are characteristic of a wide range of man-made habitats such as gardens, parks or urban spaces. Nowadays, low-maintenance perennial beds are becoming popular in horticulture and urban planning. Due to low levels of management and good records of initial plantation, perennial beds are suitable for studying vegetation processes such as competition amongst garden ornamentals and succession. We studied perennial flowerbeds in the Czech Republic that had a known initial composition at the time of establishment in 2006–2010 and we compared this with their state in 2016. We aimed to assess (i) how planted ornamental assemblages changed during 10 years of succession, and (ii) whether initial assemblage composition determined the pattern of change. We observed a decrease in biodiversity from initial plantation to the recent state across all flowerbeds in the experimental garden. In terms of diversity and stability, species-rich assemblages, mostly composed of taxa native to prairies, were the most stable. The most successful taxa (i.e. reaching high abundances with good persistence) originated from North American and Mediterranean regions

Changes in assemblages of native and alien plants in perennial plantations: prairie species stabilize the community composition

Ornamental plantations are characteristic of a wide range of man-made habitats such as gardens, parks or urban spaces. Nowadays, low-maintenance perennial beds are becoming popular in horticulture and urban planning. Due to low levels of management and good records of initial plantation, perennial beds are suitable for studying vegetation processes such as competition amongst garden ornamentals and succession. We studied perennial flowerbeds in the Czech Republic that had a known initial composition at the time of establishment in 2006–2010 and we compared this with their state in 2016. We aimed to assess (i) how planted ornamental assemblages changed during 10 years of succession, and (ii) whether initial assemblage composition determined the pattern of change. We observed a decrease in biodiversity from initial plantation to the recent state across all flowerbeds in the experimental garden. In terms of diversity and stability, species-rich assemblages, mostly composed of taxa native to prairies, were the most stable. The most successful taxa (i.e. reaching high abundances with good persistence) originated from North American and Mediterranean regions