1- How do you empirically separate extinction risk caused by underuse from extinction risk caused by overuse, habitat fragmentation, invasive species, or climate change?
If you cannot attribute a specific extinction rate to underuse, then your proposed objective use of the term collapses. What concrete metric would you actually measure in the field?
2- Your framework assumes an optimal level of use exists for biodiversity. But who defines optimal?
In your own review, Europe sees abandonment as a problem, while North America often sees human removal as conservation success. Isn’t this a value judgment, not a scientific threshold? Without a universal benchmark, how is this falsifiable?
3- You exclude developing countries and focus only on affluent regions, yet you claim a global research agenda.
How can you generalize extinction thresholds or governance strategies without including social-ecological systems where underuse is rare because overuse and poverty-driven land conversion dominate? Isn’t your sample fundamentally biased from the start?
