Alien species pools: another determinant of the habitat level of invasion
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| Year of publication | 2013 |
| Type | Conference abstract |
| Citation | |
| Description | The growing number of studies that reveal habitats to differ significantly in the number of alien species received (level of invasion) has led to a quest for the responsible mechanisms. Numbers of alien plant species in habitats have been shown to be determined by (i) habitat invasibility confined by habitat properties and (ii) propagule pressure. Here we suggest another important factor: (iii) number of species adapted to various habitats within the global pool of aliens. Habitats in the native range of alien species donate different numbers of their species as invaders to other regions.These species are adapted to their donor habitats and thus can have an advantage while invading analogous habitats in the invaded range. As a consequence, particular habitats can by highly invaded if analogous habitats in remote areas provide more species for invasion. Using a model of alien species exchange between Europe and eastern North America, we analysed the relationship between the numbers of native species donated from particular habitats of the native range for invasion and the numbers of these species found as aliens in analogous habitats of the invaded range. We used the Czech National Phytosociological Database and the Carolina Vegetation Survey Database to identify 12 habitat types occurring in both central Europe and eastern North America. We randomly selected 6059 vegetation plots of an area of 10 m2 and 100 m2 assigned to these habitat types. We used sample-based rarefaction to calculate the number of native species donated as aliens by each habitat in one region and the number of alien species received by analogous habitats in the other region, i.e. the level of invasion. We performed major axis regression and found that habitat levels of invasion in one region positively depend on the numbers of species donated by analogous habitats in the other region. This relationship was significant for both the invasion of European plant species to North American habitats (R2 = 0.285, P = 0.035) and invasion of North American species to European habitats (R2 = 0.241, P = 0.030). Our results indicate that habitats can have higher numbers of alien species not only because they are more invasible, but also because there is larger proportion of alien species ecologically compatible to them within the global alien species pools. |
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