Data for: Contrasting response of native and non-native plants to disturbance and herbivory in mountain environments

Aim: Climate warming and increasing human disturbance are expected to
promote non-native plant invasions in mountain ecosystems. Although
biological invasions are also expected to be modulated by biotic
interactions, it is still not clear how invertebrate herbivores can affect
plant invasion dynamics. Using a large manipulative experiment, we aimed
at testing: 1) the effect of soil disturbance and elevation on native and
non-native plant communities, and 2) the effect of plant-herbivore
interactions, nitrogen deposition, and elevation in driving plant
establishment after soil disturbance. Location: European Alps, NE Italy
Taxon: Vascular plants Methods: We selected remote, uninvaded dry
semi-natural grasslands along the core elevational range of non-native
plants in the European Alps (0-1330 m) and manipulated soil disturbance,
nitrogen deposition, and invertebrate herbivory. Then, we followed the
natural establishment under real field conditions of both native and
non-native plants over one growing season. We used generalized
mixed-effects models to test the effects of the experimental treatments.
Results: Native and non-native species showed contrasting responses to
soil disturbance and elevation. Low elevations and disturbance promoted
non-native success, while affecting native species diversity negatively.
Two-thirds of the experimental sites acquired novel non-natives after
disturbance. Most of the observed non-natives were not present in the
surrounding vegetation as mature plants, indicating that propagules were
able to reach even remote natural areas. While current N deposition levels
did not affect plant establishment, we found that after disturbance
invertebrate herbivory might play an important role in facilitating
non-native invasions by reducing native cover. Main conclusions: Our
findings show that highly resistant ecosystems such as continuous
grasslands can be easily invaded once the resident vegetation has been
removed, and that natural herbivory pressure from invertebrates might
amplify the negative effects of disturbance on resident native species
irrespective of elevation. Together, these results indicate increasing
risks of future plant invasions on mountains under global change.