# Ecological features facilitating spread of alien plants along Mediterranean mountain roads

## TL;DR

This study explores how roads in Mediterranean mountains help invasive plants spread, showing that disturbed soils and certain plant communities are key factors.

## Contribution

The study introduces a novel use of ecological indicator values and machine learning to assess alien plant spread along roads in Mediterranean mountains.

## Key findings

- Alien species occurrence is higher near roads with disturbed soils and in warm, light-adapted plant communities.
- Alien species cover is more strongly linked to moderate grazing and nitrophilic plant communities.
- The study provides a baseline for managing invasive plants in Mediterranean mountain ecosystems.

## Abstract

Invasive alien species represent a major threat to global biodiversity and the sustenance of ecosystems. Globally, mountain ecosystems have shown a degree of resistance to invasive species due to their distinctive ecological features. However, in recent times, the construction of linear infrastructure, such as roads, might weaken this resistance, especially in the Mediterranean basin region. Roads, by acting as efficient corridors, facilitate the dispersal of alien species along elevation gradients in mountains. Here, we investigated how the ecological features and road-associated disturbance in native plant communities affected both the occurrence and cover of alien plant species in Central Apennines (Italy). We implemented the MIREN road survey in three mountain transects conducting vegetation sampling in plots located both adjacent to and distant from the roads at intervals of ~ 100 m in elevation. We then used community-weighted means of Ecological Indicator Values for Europe together with Disturbance Indicator Values applied to plant species of native communities as predictors of alien species occurrence and cover in a machine-learning classification and regression framework. Our analyses showed that alien species’ occurrence was greater in proximity to the road where high soil disturbance occurred and in warm- and light-adapted native communities. On the other hand, alien species cover was more strongly related to moderate grazing pressure and the occurrence of nitrophilic plant communities. These findings provide a baseline for the current status of alien plant species in this Mediterranean mountain region, offering an ecological perspective to address the challenges associated with their management under global change.

The online version contains supplementary material available at 10.1007/s10530-024-03418-y.