The role of long-distance dispersal and mycorrhizas on plant colonisation within mainland Germany

Abstract

The geographical distribution of species generally reflects their ability to colonise large habitats. Thus, research on species traits affecting the ability of species to colonise (i.e. arrive and establish) new territories is required. Our study investigates whether mycorrhizas and long-distance dispersal (LDD) syndromes play an important role in plant species distribution within mainland Germany, and whether they interact to drive plant distribution at a large scale. Using a dataset of 1070 vascular plant species containing information on LDD syndromes, mycorrhizal status, and distribution, we fitted phylogenetic generalised least squares regression models to assess the effects of LDD syndromes and mycorrhizas on plant distribution across Germany. Our study showed that species with LDD syndromes tended to be more widely distributed overall than species without any specialised dispersal structures relevant for LDD (i.e. ‘unspecialised’ species). In particular, plants with nutritive tissues, which attract frugivores that disperse seeds internally, were more widely distributed than ‘unspecialised’ species. Moreover, species associated with mycorrhizal fungi, particularly the facultative mycorrhizal species, were more widely distributed than non-mycorrhizal plants. Interestingly, mycorrhizal species with LDD syndromes tended to be more widely distributed than species without any specialised dispersal structures relevant for LDD, whereas the reverse was true for non-mycorrhizal species. Our study suggests that both LDD syndromes and mycorrhizas play an important role in plant distribution within the mainland. More importantly, we show the first evidence that mycorrhizas may interact with LDD syndromes to expand the geographic distribution of plant species within the mainland.