Plant invasions are associated with lower community stability at multiple spatial scales

Plant invasions are threatening the long-term sustainability of ecosystem functions. Yet, how plant invasions impact the temporal stability of community cover across spatial scales remains poorly understood, hindering effective invasion management. Using the National Ecological Observatory Network dataset, we examine how plant invasions influence multi-scale stability of total community abundance (used total community cover) via altering community functional diversity, as well as growth and dispersal strategies. We find that invasion-associated losses of functional α diversity and functional shifts toward acquisitive strategies, reduce species asynchrony and species stability, respectively. These changes ultimately lead to lower temporal stability at the local scale (α stability). Meanwhile, invasion-associated functional shifts toward acquisitive seed dispersal strategies weaken functional β diversity, which reduces asynchrony community dynamics among local communities (spatial asynchrony). These concurrent declines in α stability and spatial asynchrony collectively destabilize metacommunity-scale stability. Our findings reveal that plant invasions may trigger destabilizing effects across spatial scales, associated with changes in functional diversity as well as growth and dispersal strategies, underscoring the need for a multi-scale invasion management framework focusing on both local diversity and the connectivity among local communities. Plant invasions can threaten ecosystems by making plant communities less stable over time. The study shows that invasions reduce stability from local to metacommunity scales by eroding functional diversity and favoring fast-growing strategies.