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The soil seed bank plays an important role in determining what plant species emerge following the removal of monodominant invasive species. A depleted seed bank may provide a substantial barrier to site restoration, however, little is known about what changes occur in the seed bank during invasion and following clearance. This study used greenhouse germination trials to quantify and compare the seed bank present in 30 Scottish Atlantic oak woodland sites under three treatments: (1) sites featuring dense stands of the non-native invasive shrub Rhododendron ponticum; (2) sites that had been previously subject to dense R. ponticum stands but which had been cleared; and (3) uninvaded control sites. Seed banks of densely invaded and cleared sites had significantly lower species richness than those of uninvaded control sites with a lower abundance of graminoid, and to a lesser extent forb seeds than the uninvaded controls. The seed bank community composition differed significantly between the three site types. Uninvaded sites featured a wide array of species, densely invaded sites were dominated by R. ponticum seeds and cleared sites were dominated by birch (Betula sp.) seeds. Cleared sites contained very few R. ponticum seeds indicating that once effective clearance had been achieved, re-invasion would be unlikely to occur from the soil seed bank. Our findings revealed that the soil seed bank present in cleared sites was very different from the seed bank of uninvaded control sites, with clear implications for site restoration.

The Scottish Government has announced that they are minded to allow reintroduced populations of Eurasian beaver (Castor fiber), an ecosystem engineer, to remain in Scotland. Some species and habitats of conservation importance may be affected by the activities of an ecosystem engineer. The study had two key objectives: to identify the potential location of the beaver’s two ecosystem engineering activities and to assess risks to vulnerable habitats and species. To identify potential core beaver woodland, a rule-based species distribution model was developed which included a novel method of integrating beaver territory size requirements. This was used to further predict where beavers would be unlikely to dam. We used the models to assess the spatial overlap between ecosystem engineering activities (i.e. herbivory and damming) with habitats and species of conservation importance. One hundred and five thousand five hundred eighty-six hectares of core beaver woodland was identified, which predicted the location of beaver herbivory. Our model successfully predicted the location of beaver activities surveyed in the largest beaver population in Scotland. Extensive overlap was predicted between beaver herbivory and habitats of conservation importance, in particular aspen woodland, Atlantic hazelwood, and alluvial forests. Eighty-seven percent of watercourses in Scotland were outside the beaver damming model, and hence had a lower likelihood of being dammed. The majority of freshwater pearl mussel, lamprey and Atlantic salmon Special Areas of Conservation, were in river sections less likely to be dammed. If beavers recolonise their former range in Scotland, ecosystem engineering activities are likely to be extensive. However, any impacts on vulnerable species and habitats will be in specific areas and will need to be monitored.