Data from: Sensitivity analysis of conservation targets in systematic conservation planning

Systematic conservation planning has rapidly advanced in the past decade and has been increasingly incorporated in multiple studies and conservation projects. One of its requirements is a quantitative definition of conservation targets. While the Convention of Biological Diversity aims to expand the world's protected area network to 17% of the land surface, in many cases such uniform policy-driven targets may not be appropriate for achieving persistence of various species. Targets are often set arbitrarily, often because information required for the persistence of each species is unavailable or unknown in the focal region. Conservation planners therefore need to establish complementary novel approaches to address the gaps in setting targets. Here, we develop and present a novel method that aims to help guide the selection of conservation targets, providing support for decision makers, planners and managers. This is achieved by examining the overall flexibility of the conservation network resulting from conservation prioritization, and aiming for greater flexibility. To test this approach we applied the decision support tool Marxan to determine marine conservation priority areas in the Eastern Mediterranean Sea as a case study. We assessed the flexibility of the conservation network by comparing 80 different scenarios where conservation targets were gradually increased and assessed by a range of calculated metrics (e.g., the percentage of the total area selected, the overall connectivity). We discovered that when conservation targets were set too low (i.e. below 10% of the distribution range of each species) very few areas were identified as irreplaceable and the conservation network was not well defined. Interestingly, when conservation targets were set too high (over 50% of the species' range), too many conservation priority areas were selected as irreplaceable, an outcome which is realistically infeasible to implement. As a general guideline, we found that flexibility in a conservation network is adequate when about 10%-20% of the study area is considered as irreplaceable (selection frequency values over 90%). This approach offers a useful sensitivity analysis when applying target-based systematic conservation planning tools, to ensure that the resulting protected area conservation network offers more choices for managers and decision makers.系统性保护规划在过去十年间取得了长足进展，并日益被纳入多项研究与保护项目之中。其核心要求之一是对保护目标进行量化界定。尽管《生物多样性公约》（Convention of Biological Diversity）旨在将全球陆地保护地网络扩展至陆地总面积的17%，但在多数场景下，这类统一的政策导向型目标或许并不足以保障各类物种的存续。保护目标往往是随意设定的，这通常是因为研究区域内缺乏或未掌握各物种存续所需的相关信息。因此，保护规划者需要构建互补性的创新方法，以填补目标设定环节的空白。本研究提出一种全新方法，旨在辅助保护目标的遴选工作，为决策者、规划者与管理者提供决策支持。该方法通过评估保护优先级划定所形成的保护网络的整体弹性，并以提升弹性为目标来实现上述辅助作用。为验证该方法的有效性，我们以地中海东部海洋保护优先区域划定为案例，应用决策支持工具Marxan开展了相关研究。我们通过对比80组不同情景评估保护网络的弹性：在这些情景中，保护目标逐步提升，并通过一系列计算指标（如选定区域占总面积的比例、整体连通性）进行评估。研究发现，当保护目标设定过低（即低于各物种分布范围的10%）时，几乎没有区域被认定为不可替代，保护网络的界定也不够清晰。值得注意的是，当保护目标设定过高（超过物种分布范围的50%）时，会有过多的保护优先区域被认定为不可替代，这一结果在现实中难以落地实施。本研究得出的一般性指导原则为：当研究区域内约10%~20%的区域被认定为不可替代（即遴选频率超过90%）时，保护网络的弹性足以满足需求。该方法可为基于目标的系统性保护规划工具的应用提供有效的敏感性分析，确保最终形成的保护地网络能够为管理者与决策者提供更多选择空间。