Private Provision of a Public Good: Land Trust Membership
研究了91个土地信托的会员数量与公共物品收益的关系，发现会员制能提高会员数，但多数信托不提供此类收益；会员数随人口增长但增速递减，存在搭便车行为。
<i>Land trusts prevent the development of open space, providing both public and impure public goods to area residents. This study examines the relationship between these benefits and membership levels for a sample of 91 land trusts, while controlling for local demographic and area characteristics. Trusts that offer member-only access to property have higher membership, but most trusts do not provide such benefits. Membership increases with local population, but at a decreasing rate, consistent with the free-riding behavior found in other studies of collective action. The study finds the existence of scope effects with respect to the amount of protected acreage.</i>