Table 1.

Realized and potential impact sub-indicators including priority species subset considered, interpretation and implications for management. Realized impact sub-indicators (1.1–1.3) are quantified from regional impact evidence, while potential impact sub-indicators (2.1–2.3) are quantified based on global impact evidence. Proposed sub-indicators for which impact data are not currently available are indicated with asterisks.

sub-indicators	priority species subset	indicator interpretation		implications for policy and management
		distribution	trends
1.1. Realized total impact	All observed IAS with regional impact evidence	Degree of impact documented regionally	Growth in impact of established invaders over time across regions (global) or per region (regional)	To prioritize management of established invaders with confirmed regional impacts
1.2. Realized impact mechanisms*	Observed IAS with regional impact mechanism evidence	Degree to which different impact mechanisms are documented to influence native species assemblages	Growth in the impact of established invaders on native biodiversity and ecosystems via specific impact mechanisms	To prioritize management of established invaders for conservation of native taxa or ecosystems that are vulnerable to specific mechanisms of impact
1.3. Realized worst invaders*	Observed IAS with major or severe regional impact evidence	Degree of impact by the regionally worst invaders documented currently	Growth in impact of the worst established invaders over time	To prioritize management of worst invaders that are known to have the largest negative impact on native species and ecosystems
2.1. Potential total impact	All observed IAS with global impact evidence	Degree of impact from the regional IAS potentially unobserved	Growth in potentially unobserved impact of IAS over time across regions (global) or per region (regional)	To prioritize management of invasive species (including new, unassessed and established invaders) in a region
2.2. Potential impact mechanisms	Observed IAS with global impact mechanism evidence	Degree to which different impact mechanisms could be influencing native species assemblages	Growth in the potential impact of invasive species on native biodiversity and ecosystems via specific impact mechanisms	To prioritize management of invasive species (including new, unassessed and established invaders) for conservation of native taxa or ecosystems that are vulnerable to specific mechanisms of impact
2.3. Potential worst invaders	Observed IAS with major or severe global impact evidence	Degree to which impact could be occurring regionally due to globally important invaders	Growth in the potential impact of the worst invasive species on native biodiversity and ecosystems via specific impact mechanisms	To prioritize management of the worst invaders globally that are most likely to have future negative impacts on native species and ecosystems