Jan Pergl, Michaela Vítková, Martin Hejda, Josef Kutlvašr, Petr Petřík, Jiří Sádlo, Martin Vojík, Anna Lučanová and Petr Pyšek
The Czech Academy of Sciences, Institute of Botany, Průhonice 252 43, Czech Republic
There is an ongoing debate on whether invasive alien species impose a greater threat to biodiversity compared to native species which are spreading in current landscapes heavily transformed by humans. However, a quantitative assessment on whether the impacts of these two groups of contrasting origins differ is missing. We measured the impacts of dominant invasive alien and native expanding plants in the Czech Republic, Central Europe, on plant communities (species composition and diversity) and soil ecosystem (physico-chemical properties and activity of soil biota). Quantifying the difference in impact between the two groups of dominant species makes it possible to express the net impact of invasive aliens.
Here, we present first results from soil analyses in sites dominated by native vs alien species. We studied five native dominants (Calamagrostis epigejos, Filipendula ulmaria, Phalaris arundinacea, Rubus idaeus and Urtica dioica) and five alien dominants (Impatiens glandulifera, Lupinus polyphyllus, Reynoutria sp., Solidago sp. and Telekia speciosa). Seasonal nutrient availability and soil microbial activity were sampled three times during the vegetation season, for four weeks in each sampling period time. For nutrient availability, we used PRS ion exchange probes that measured NO3–-N, NH4+-N, P, K, S, Ca, Mg, Mn, Al, Fe, Cu, Zn, B, Pb, and Cd. Microbial activity and soil fauna were analysed by burying bags with pure cellulose paper and three different mesh sizes to account for different size groups of fauna (0.1 mm – permeable to bacteria, fungi and protozoa; 1 mm – permeable to microflora, micro-and meso-arthropods; and 4 mm – freely permeable to soil fauna). The differences among the impacts of dominant native and alien plants will be discussed.