Number 15/Life & ecology/Conservation
The Extinction Debt Half-Life
The quantity
The time for half of the committed but unrealised extinctions following habitat loss to become realised.
01Why it matters
It tells you how long a protected area must persist before its species list is secure, which is the question that decides reserve design.
02Expected value
Decades for vertebrates, centuries for trees.
03How it would be measured
Long-term resurveys of fragments with known loss dates.
04What would refute it
Immediate realisation would make the half-life zero and the debt concept unnecessary.