Overall, increasing internal bonuses over external ones thus allows improving AB cost-effectiveness. Interestingly, landowners mostly enroll individually in such differentiated ABs.

As such, habitat agglomeration doesn’t always need cooperation—it just needs smart incentives.

10/10

To overcome this issue, the regulator must raise external bonuses high enough to make each landowner better off independently.

This makes external conservation more expensive than internal bonuses. Cooperation is costly!

9/10

External bonuses are trickier: both landowners must find it individually worthwhile to conserve. If just one of them faces a higher cost than the bonus, the deal collapses and the AB does not work—because they can’t compensate each other (while they can within landholdings)

8/10

Here’s the intuition:

For internal bonuses, only the total surplus from the two plots matters. If the combined bonus exceeds the combined opportunity cost, the landowner will conserve both plots—no matter how the gains are split.

7/10

Our simulations—calibrated with French data—show a clear pattern:

When the regulator's budget is limited, undifferentiated ABs (same internal & external bonuses) perform best.
But as the budget grows, prioritizing internal bonuses becomes increasingly cost-effective. Why?

6/10

So we ask ourselves whether regulators should differentiate between these two types of bonuses?

To answer, we develop a spatially explicit ecological-economic game, with landowners choosing whether to cooperate and what to conserve, under a fixed regulatory budget.

5/10

Why? Because external bonuses involve cooperation problems: two landowners must agree to conserve plots side-by-side.

Internal bonuses avoid this: a single landowner can conserve multiple adjacent plots without negotiating with others. This improves AB cost-effectiveness.

4/10

Most ABs reward landowners when two conserved plots are adjacent, regardless of who owns the plots.

Yet, the two plots can be either on the same landholding (internal bonus), or on different landholdings (external bonus).

Raphaël and I show that this distinction matters.

3/10

This work extends my 2023 paper with @mzavalloni.bsky.social in AJAE, where we showed that landowners enroll into agglomeration bonus (AB) in small groups—not the idealized "grand coalition" often assumed in previous AB models.

That finding led us to rethink how incentives work.

2/10

Malheureusement le devoir m’appelle à Milan ! (Tu viens à l’IAERE à Rome la semaine prochaine ?)

La BNVD est disponible elle. Quelles sont ses limites pour vos recherches ? (Au delà du fait que achats ≠ utilisations)