The interplay of landscape connectivity and composition in the alien plant invasions of ecological networks

Biological invasions are deemed to be the second most important global driver of biodiversity loss showing strong interactions with the aftermaths of habitat destruction and landscape fragmentation. The role of landscape structure in biological invasions is widely considered while its interplay with landscape connectivity is less understood. However, ecological connectivity can be equally crucial for both native and alien species, constituting the backbone of ecological network initiatives. We parsed the relationships between α and β diversity of alien and native plants, landscape structure and connectivity in the habitats composing the nodes of an EN developed in agricultural landscapes. We found contrasting effects of connectivity and landscape structure for native and alien communities. In particular, we observed a positive relationship between high connectivity and native plant diversity and a more evident influence of landscape structure in shaping alien communities. These results were often habitat-depending, showing stronger influence for woods, where alien α diversity increased with fragmentation while native richness declined. Moreover, native species diversity was more tightly linked to ecological connectivity, while alien species were mainly associated with landscape configuration. Our findings suggest that landscape planning aimed at enhancing landscape connectivity and reducing landscape disturbance might greatly improve the resistance of landscapes to biological invasions and increase native species richness. In ecological networks, a shift of intensive to extensive land uses, by implementing green infrastructures, seems to be a win–win solution favoring native species while controlling the oversimplification of plant species composition due to alien plant invasion.