Invasion of central-European habitats by the moss Campylopus introflexus.

Although invasions by vascular plants are frequently studied, little is known about invasive bryophytes. Campylopus introflexus is an invasive moss endangering natural vegetation in western Europe and currently extending its secondary area eastwards. Therefore, we studied its ecology in the Czech Republic (central Europe). We updated its distribution, described colonized habitats in term of the composition of the vegetation, investigated substrate and water demands and which habitats in the Czech Republic are potentially at risk of invasion by C. introflexus. The first dataset contained 78 vegetation plots with C. introflexus from across the whole of the area investigated and included all the habitats colonized. The second dataset contained results of previous studies of the vegetation of pine forests both with and without C. introflexus and was used to determine the fine scale features of its habitat preferences within this habitat. Records of the vegetation plots in both datasets were numerically classified. We further calculated the similarity of the species composition of vegetation plots with C. introflexus with that of 26,998 vegetation plots without C. introflexus that were stored in a large database in order to predict the habitats that were likely to be colonized. Ecological demands were characterized by in situ research (soil samples from 52 vegetation plots) and ecological interpretation of the pine forest dataset. Further, a cultivation experiment was established with populations from 20 of the sites studied in order to test the ability of C. introflexus to grow in different soil and moisture conditions, and the data were evaluated by linear mixed effect models. We found that C. introflexus invades dry, nutrient poor acidic soils in a range of vegetation types, and is most common in coniferous forest plantations and drained bogs, where it colonizes open patches resulting from anthropogenic disturbance where there is little competition from other plants. The vegetation plots from the database that were similar in species composition to those with C. introflexus are mainly forest habitats broadly distributed in the Czech Republic. Cultivation experiments showed that this species does badly when growing in lime-rich or waterlogged soils. We conclude that the species has the potential to be common in central Europe because of the wide range of habitats with favourable vegetation compositions and ecological parameters. However, it presently represents no risk for endangered plant species and communities.