Net outcome-type biodiversity policies are proliferating globally as perceived mechanisms to reconcile economic development and conservation objectives. The UK government's Environment Bill will mandate that most new developments in England demonstrate that they deliver a biodiversity net gain (BNG) to receive planning permission, representing the most wide-ranging net outcome type policy globally. However, as with many nascent net-outcome policies, the likely outcomes of mandatory BNG have not been explored empirically. We assemble all BNG assessments (accounting for ∼6% of England's annual housebuilding and other infrastructure) submitted from January 2020 to February 2021 in six early-adopter councils who are implementing mandatory no net loss or BNG requirements in advance of the national adoption of mandatory BNG, and analyze the aggregate habitat changes proposed. Our sample is associated with a 34% reduction in the area of nonurban habitats, generally compensated by commitments to deliver smaller areas of higher quality habitat years later in the development project cycle. Ninety-five percent of biodiversity units delivered in our sample come from habitats within or directly-adjacent to the development footprint managed by the developers. However, we find that these gains fall within a governance gap whereby they risk being unenforceable, a challenge that is shared with other net outcome type policies implemented internationally.

中文翻译：

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利用英格兰早期采用者司法管辖区的证据探索强制性生物多样性净收益的生态结果

净结果型生物多样性政策正在全球范围内扩散，作为协调经济发展和保护目标的公认机制。英国政府的环境法案将要求英格兰的大多数新开发项目证明它们提供了生物多样性净收益 (BNG) 以获得规划许可，这代表了全球范围最广的净成果类型政策。然而，与许多新生的净结果政策一样，强制性 BNG 的可能结果尚未经过实证研究。我们汇总了 2020 年 1 月至 2021 年 2 月期间在六个早期采用者委员会提交的所有 BNG 评估（占英格兰年度房屋建筑和其他基础设施的 6%），这些早期采用者委员会在国家采用强制性无净损失或 BNG 要求之前实施了强制性要求天然气，并分析提议的总体栖息地变化。我们的样本与非城市栖息地面积减少 34% 相关，通常通过承诺在开发项目周期后几年提供更小面积的高质量栖息地来补偿。在我们的样本中，95% 的生物多样性单元来自开发商管理的开发足迹内或直接相邻的栖息地。然而，我们发现这些收益属于治理差距，因此它们可能无法执行，这是与国际实施的其他净结果类型政策共同面临的挑战。通常通过承诺在开发项目周期后几年提供更小面积的高质量栖息地来补偿。在我们的样本中，95% 的生物多样性单元来自开发商管理的开发足迹内或直接相邻的栖息地。然而，我们发现这些收益属于治理差距，因此它们可能无法执行，这是与国际实施的其他净结果类型政策共同面临的挑战。通常通过承诺在开发项目周期后几年提供更小面积的更高质量的栖息地来补偿。在我们的样本中，95% 的生物多样性单元来自开发商管理的开发足迹内或直接相邻的栖息地。然而，我们发现这些收益属于治理差距，因此它们可能无法执行，这是与国际实施的其他净结果类型政策共同面临的挑战。