Ecological Risk-Benefit Analysis for Assisted Colonization

Area of Science:

• Conservation Biology
• Ecology
• Biodiversity Management

Background:

• Assisted colonization (AC) is a conservation strategy to prevent species extinction by translocating them outside their native range.
• AC is controversial due to potential negative ecological impacts, including risks to native species and novel interactions, mirroring invasive species concerns.
• Existing AC guidelines lack case-specific risk-benefit analyses for biodiversity.

Purpose of the Study:

• To develop a comprehensive framework for decision-making regarding assisted colonization (AC) projects.
• To differentiate between low-risk, high-benefit AC cases and high-risk, low-benefit scenarios.
• To establish a quantitative approach for assessing AC's impact on resident species and global biodiversity.

Main Methods:

• Proposed a two-pronged approach: 1) qualitative criteria for clear-cut AC cases, and 2) quantitative analysis for complex cases.
• Developed seven qualitative criteria to identify AC projects with minimal risk and maximal benefit, or vice versa.
• Outlined a roadmap for a quantitative system based on community ecology theory to estimate extirpation probabilities.

Main Results:

• The qualitative criteria can identify obviously suitable or unsuitable AC projects, simplifying decision-making.
• The proposed framework allows for quantitative risk assessment, estimating the probability of native species' extirpation due to AC.
• The decision framework recommends AC only if it increases the number of globally extant species compared to inaction.

Conclusions:

• A structured, two-step approach (qualitative and quantitative) is needed for robust risk assessment in assisted colonization.
• Further development and large-scale testing of the proposed framework are recommended.
• Wide consultation is crucial for adopting international guidelines for AC risk assessment to ensure biodiversity protection.