Private land protection is an important and growing tool to address biodiversity loss and climate change. Thus, better empirical evidence on the effectiveness of private land protection and organizational practices, such as targeting of lands for protection and choice of protection mechanism (i.e., fee simple land acquisition and conservation easements), is needed. We addressed this gap by estimating the impacts of The Nature Conservancy's (TNC) (a large nongovernmental organization with relatively decentralized management) conservation land acquisitions and easements from 1988 to 2016 in three regions of the United States (Mid-Atlantic, New England and New York, and California). We estimated impact in terms of avoided conversion by comparing natural land cover on 3179 protected parcels with matched unprotected parcels. Nineteen of 21 ecoregional plans used threats of agriculture and development to identify priorities for protection. When regions and protection mechanisms were pooled, on average there was no evidence of avoided conversion from 1988 to 2016. Accounting for mechanisms, TNC land acquisitions avoided conversion and easements did not. TNC's easements on parcels acquired by conservation partners did avoid conversion. Limitations of these results include focus on a single measure of impact, inability to capture future avoided conversion, and low land cover change accuracy in California. Our results suggest that private land protection managers who seek to avoid land conversion in the near to medium term should increase focus on areas with higher threats. Special attention should be paid to strengthening accountability and the role of partners, improving or clarifying how easements are used, and facilitating the flow of resources to work with the greatest potential impact.

中文翻译：

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了解不同地区私人保护区和保护机制的影响差异，为组织实践提供信息

私人土地保护是解决生物多样性丧失和气候变化问题的重要且不断发展的工具。因此，需要更好的实证证据来证明私人土地保护和组织实践的有效性，例如保护土地的目标和保护机制的选择（即简单的土地征用和保护地役权）。我们通过评估大自然保护协会 (TNC)（管理相对分散的大型非政府组织）1988 年至 2016 年在美国三个地区（中大西洋地区、新英格兰地区和新英格兰地区）保护性土地收购和地役权的影响来解决这一差距。约克和加利福尼亚）。我们通过比较 3179 个受保护地块和匹配的未受保护地块的自然土地覆盖情况，估计了避免转换方面的影响。 21 个生态区域计划中有 19 个利用农业和发展的威胁来确定保护的优先事项。当将地区和保护机制合并起来时，平均而言，没有证据表明从 1988 年到 2016 年避免了转换。考虑到机制，跨国公司的土地收购避免了转换，而地役权却没有。 TNC 对保护合作伙伴收购的地块的地役权确实避免了转换。这些结果的局限性包括关注单一影响指标、无法捕捉未来避免的转化以及加利福尼亚州土地覆盖变化的准确性较低。我们的研究结果表明，寻求在中短期内避免土地转换的私人土地保护管理者应更加关注威胁较高的地区。应特别注意加强问责制和合作伙伴的作用，改进或澄清地役权的使用方式，并促进资源流动以发挥最大的潜在影响。