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We assessed the impact of road disturbances on the dominant mycorrhizal types in ecosystems at the global level and how this mechanism can potentially lead to lasting plant community changes. We used a database of coordinated plant community surveys following mountain roads from 894 plots in 11 mountain regions across the globe in combination with an existing database of mycorrhizal–plant associations in order to approximate the relative abundance of mycorrhizal types in natural and disturbed environments. Our findings show that roadside disturbance promotes the cover of plants associated with arbuscular mycorrhizal (AM) fungi. This effect is especially strong in colder mountain environments and in mountain regions where plant communities are dominated by ectomycorrhizal (EcM) or ericoid‐mycorrhizal (ErM) associations. Furthermore, non‐native plant species, which we confirmed to be mostly AM plants, are more successful in environments dominated by AM associations. These biogeographical patterns suggest that changes in mycorrhizal types could be a crucial factor in the worldwide impact of anthropogenic disturbances on mountain ecosystems. Indeed, roadsides foster AM‐dominated systems, where AM‐fungi might aid AM‐associated plant species while potentially reducing the biotic resistance against invasive non‐native species, often also associated with AM networks. Restoration efforts in mountain ecosystems will have to contend with changes in the fundamental make‐up of EcM‐ and ErM plant communities induced by roadside disturbance. [ABSTRACT FROM AUTHOR]

Summary: Plant associated mutualists can mediate invasion success by affecting the ecological niche of nonnative plant species. Anthropogenic disturbance is also key in facilitating invasion success through changes in biotic and abiotic conditions, but the combined effect of these two factors in natural environments is understudied.To better understand this interaction, we investigated how disturbance and its interaction with mycorrhizas could impact range dynamics of nonnative plant species in the mountains of Norway. Therefore, we studied the root colonisation and community composition of arbuscular mycorrhizal (AM) fungi in disturbed vs undisturbed plots along mountain roads.We found that roadside disturbance strongly increases fungal diversity and richness while also promoting AM fungal root colonisation in an otherwise ecto‐mycorrhiza and ericoid‐mycorrhiza dominated environment. Surprisingly, AM fungi associating with nonnative plant species were present across the whole elevation gradient, even above the highest elevational limit of nonnative plants, indicating that mycorrhizal fungi are not currently limiting the upward movement of nonnative plants.We conclude that roadside disturbance has a positive effect on AM fungal colonisation and richness, possibly supporting the spread of nonnative plants, but that there is no absolute limitation of belowground mutualists, even at high elevation. See also the Commentary on this article by Bueno et al., 230: 883–885. [ABSTRACT FROM AUTHOR]

The negative impact of invasive alien plants (IAPs) in protected areas (PAs) is managed through control programmes, often using area‐based management, where identified IAPs in management units are controlled simultaneously. However, this approach has shortfalls, including the methods used to prioritise management units, spatial grain dependence and spatial interdependence of management units. Species‐based management approaches, though used less frequently, are usually aimed at eradication.We propose using a Commonness framework to reconcile area‐based and species‐based management approaches, viewing the invasion process as a population trajectory from uncommon to common. The framework assigns species to one of eight commonness types at a given scale using three species characteristics: local population size (small/large), geographic range (wide/narrow) and spatial pattern (even/clumped). These metrics were calculated using a comprehensive fine‐scale IAP dataset from Table Mountain National Park, South Africa, at six scales of increasing spatial grain, enabling quantification of the effects of scale and species' range structure on management potential of IAPs.Most species exhibited the Point Source commonness type at fine spatial grains, requiring Rapid Response, Reconnaissance or Sweeping management strategies. At coarser grains, species were mostly classed within wide occupancy ranges, with small population sizes (Dispersed and Sparse types). The Control strategy currently applied in the area (best suited for large populations across a narrow range) should be re‐evaluated given the progress made by historical clearing in reducing commonness. Using a phylo‐tree, we identified adjacent areas that require different strategies as well as changes in species‐specific goals at particular sites with increasing grain coarseness. For example, species generally deemed to be common, for which a Control strategy is applied, may require Rapid Response type strategies for isolated and/or small, clumped subpopulations.Synthesis and applications. We use a Commonness framework to quantify patterns of plant invasion at multiple spatial scales. We demonstrate how different management strategies are appropriate for the same species in different parts of its invaded range, and how these nuances are often obscured through the use of coarse data. The framework enables tailoring management interventions to minimise the spread and impact of invasive alien plants. [ABSTRACT FROM AUTHOR]

The number and rate of non‐native plant invasions in forests have been steadily increasing over the last century with profound consequences for the composition, structure and functioning of these ecosystems. While multiple regional, landscape and local environmental factors are known to drive the spread of non‐native invasive plant species (NNIPS) into forests, such factors have rarely been analysed within a unified analytical framework allowing for the assessment of their relative importance, possible non‐linear behaviour and interactions. Obtaining such knowledge would improve the understanding and allow prediction of forest plant invasions and help prioritize actions for effective NNIPS control and mitigation.We used boosted regression trees and Bayesian non‐linear regression to analyse forest inventory data spanning 14 northern US states in combination with data on climate, land use and disturbance. Within each framework, we assessed the magnitude, direction and functional form of the effects of 18 regional to local environmental factors and their interactions on the probability of presence and richness of NNIPS in the forest understory, while controlling for sampling intensity, data collection time and spatial autocorrelation.The studied drivers together captured nearly 50% of the variation in NNIPS occurrence and richness and were sufficient to obtain sensible predictions. Most drivers exhibited monotonic non‐linear individual effects and several drivers showed non‐additive combined effects. Temperature and landscape openness were the two major determinants of NNIPS presence and richness, but their effects were to a different degree moderated by elevation, climatic and topographic wetness, and stand age. Stand age was a more important predictor of NNIPS invasion than stand productivity. Deer density tended to be positively associated with NNIPS, whereas gypsy moth outbreaks possibly have increased resistance to plant invasions.Synthesis and applications. To optimize non‐native invasive plant species (NNIPS) control efforts in forests, it is important to explicitly account for the functional form and interactions among the factors operating across spatial and temporal scales. Increasing the average stand age at the landscape and regional levels is essential for buffering against further invasions. Recurrent canopy disturbance likely slowed down NNIPS invasion previously, yet whether this holds under higher propagule pressure remains unknown. [ABSTRACT FROM AUTHOR]