Voluntary, permanent land protection is a key conservation process in many coun-tries. Concerns with the effectiveness of such decentralized processes exist due tothe potential for (1) selection bias, that is, the protection of parcels whose land coverwould have been conserved in the absence of protection, and (2) local spillover effects,that is, protection increasing the likelihood that adjacent parcels lose land cover dueto additional conversion. The researchers examine the validity of both concerns using a quasi-experimental approach and a dataset of 220,187 parcels and 26 years of protectionand land-cover change in Massachusetts.

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