Alien plant invasions and native plant extinctions: a six-threshold framework

Area of Science:

• Ecology
• Conservation Biology
• Invasive Species Management

Background:

• Biological invasions pose a significant threat to global biodiversity across various taxonomic groups.
• Invasive plants are the most studied group, with ongoing debate about the extent of their threat to native plant species, including potential extinctions.
• Existing research questions whether the threat posed by invasive plants has been overstated.

Purpose of the Study:

• To provide a conceptual framework for discussing the threat of invasive plants to native species.
• To define thresholds along an 'extinction trajectory' to assess the impact of invasive plants.
• To evaluate the evidence for native plant extinctions caused by invasive plants.

Main Methods:

• Development of a conceptual framework with six defined thresholds of an 'extinction trajectory'.
• Review of evidence for native plant species' status along this trajectory due to invasive plant impacts.
• Analysis of factors that may obscure the true impact, such as data limitations and management interventions.

Main Results:

• No documented cases of native plant 'in the wild' or global extinctions solely due to plant invasions were found.
• Evidence indicates that native plants have reached intermediate thresholds on the extinction trajectory due to invasive plant impacts.
• Factors like data scarcity, time lags, and conservation interventions can mask the true extent of the threat.

Conclusions:

• The lack of documented extinctions does not diminish the significant threat posed by invasive plants to native biodiversity.
• Conservation management must focus on trends and implement interventions before species reach critical extinction thresholds.
• A clear framework is needed to accurately assess and manage the risks associated with invasive plant species.