Measuring the Effectiveness of Conservation: A Novel Framework to Quantify the Benefits of Sage-Grouse Conservation Policy and Easements in Wyoming

Increasing energy and housing demands are impacting wildlife populations throughout western North America. Greater sage-grouse (Centrocercus urophasianus), a species known for its sensitivity to landscape-scale disturbance, inhabits the same low elevation sage-steppe in which much of this development is occurring. Wyoming has committed to maintain sage-grouse populations through conservation easements and policy changes that conserves high bird abundance “core” habitat and encourages development in less sensitive landscapes. In this study, we built new predictive models of oil and gas, wind, and residential development and applied build-out scenarios to simulate future development and measure the efficacy of conservation actions for maintaining sage-grouse populations. Our approach predicts sage-grouse population losses averted through conservation action and quantifies return on investment for different conservation strategies. We estimate that without conservation, sage-grouse populations in Wyoming will decrease under our long-term scenario by 14–29% (95% CI: 4–46%). However, a conservation strategy that includes the “core area” policy and $250 million in targeted easements could reduce these losses to 9–15% (95% CI: 3–32%), cutting anticipated losses by roughly half statewide and nearly two-thirds within sage-grouse core breeding areas. Core area policy is the single most important component, and targeted easements are complementary to the overall strategy. There is considerable uncertainty around the magnitude of our estimates; however, the relative benefit of different conservation scenarios remains comparable because potential biases and assumptions are consistently applied regardless of the strategy. There is early evidence based on a 40% reduction in leased hectares inside core areas that Wyoming policy is reducing potential for future fragmentation inside core areas. Our framework using build-out scenarios to anticipate species declines provides estimates that could be used by decision makers to determine if expected population losses warrant ESA listing.

北美西部全域的能源与住房需求持续增长，正对当地野生动物种群造成负面影响。艾草松鸡（Greater sage-grouse，学名Centrocercus urophasianus）是对景观尺度干扰高度敏感的物种，其栖息的低海拔艾灌丛草原恰好是此类开发活动集中分布的区域。怀俄明州已承诺通过保护地役权与政策调整维持艾草松鸡种群规模：相关政策旨在保护鸟类种群密度较高的"核心"栖息地，并鼓励在生态敏感度较低的区域开展开发活动。本研究构建了针对油气、风电与住宅开发的全新预测模型，并采用全开发（build-out）场景模拟未来开发态势，以此评估各类保护措施对维持艾草松鸡种群的实施成效。本研究方法可测算保护行动所避免的艾草松鸡种群损失量，并量化不同保护策略的投资回报率。研究估算，若不采取任何保护措施，怀俄明州的艾草松鸡种群在长期模拟场景下将减少14%至29%（95%置信区间：4%至46%）。但若采用包含"核心区域"政策与2.5亿美元定向保护地役权的保护策略，种群损失可降至9%至15%（95%置信区间：3%至32%）：全州范围内的预计损失将减少约一半，而在艾草松鸡核心繁殖区内的损失降幅则接近三分之二。核心区域政策是该保护策略中最为核心的组成部分，定向保护地役权则是整体策略的有益补充。尽管本研究的估算值存在较大不确定性，但由于所有策略均采用一致的潜在偏差控制与假设前提，不同保护场景的相对效益仍具备可比性。现有初步证据显示，怀俄明州的相关政策已通过将核心区内租赁土地面积减少40%，降低了核心区域未来发生生境破碎化的潜在风险。本研究所构建的、基于全开发场景预判物种种群下降的分析框架，所得估算结果可供决策者参考，以判断预估的种群损失是否需要触发《美国濒危物种法》（Endangered Species Act, ESA）的物种列入保护名录程序。