Unveiling spatial patterns and trajectories of shrub dynamics in Mediterranean alpine ecosystems

Shrub encroachment in alpine and subalpine environments has raised concerns in recent decades, particularly due to climate change and shifts in land use. This study investigates the varying impacts of shrub invasion on different alpine and subalpine herbaceous communities and analyzes the spatial characteristics of shrub invasion. Three sites in the central Italian Apennines were examined by comparing vegetation maps from 1954 and 2016, alongside environmental variables such as slope, ruggedness, elevation, and soil fertility. The findings indicate that alpine shrub vegetation more successfully invades open herbaceous communities compared to closed grasslands with nutrient-rich soils, which are more resistant to shrub invasion. The invasion process predominantly involves the expansion of existing shrub patches, gradually overtaking grasslands. This selective pattern of shrub invasion highlights the significance of varying competition dynamics in changing high-elevation ecosystems globally.