There is considerable evidence that keeping propagule pressure low can drastically reduce establishment probability of potential invasive species. Yet, most management plans and research efforts fail to explicitly acknowledge all three of the components of propagule pressure: size, number, and the risk–release relationship. It is unclear how failing to specify one or more of these components can influence the efficacy of management plans in preventing invasive species establishment. Furthermore, even if all components are acknowledged and quantified, there currently is no mathematical tool available to calculate the levels of propagule pressure that ensure attainment of a predetermined, and system-specific, target establishment probability. Here, we quantify the resulting uncertainty in establishment probability when one or more components of propagule pressure is unknown by using parameter uncertainty analysis on realistic values of propagule pressure. In addition, to aid in the development of management plans that explicitly set propagule pressure limits, we develop a propagule-pressure sensitivity analysis that we use to determine the required reduction in levels for propagule size and number (representative of management actions) to maintain a target establishment probability. We show that the precision of establishment estimates is highly dependent on knowledge of all three propagule pressure components, where the possible range of values for establishment probability can vary by over 50% without full specification. In addition, our sensitivity analysis showed that propagule size and number can be altered independently or in conjunction to lower establishment probability below a target level. Importantly, our sensitivity analysis was able to specifically quantify how much reduction in a propagule pressure component(s) is needed to reach a given target establishment probability. Our findings suggest that quantifying the three components of propagule pressure should be a priority for invasive species prevention moving forward. Furthermore, our sensitivity analysis tool can serve to guide the development of new invasive species management plans in a transparent and quantitative manner. Together with information on the costs associated with approaches to reducing propagule pressure, our tool can be used to identify the most cost-effective approach to prevent invasive species establishments.

中文翻译：

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管理繁殖体压力以防止入侵物种建立：繁殖体大小、数量和风险释放曲线

有大量证据表明，保持低繁殖体压力可以大大降低潜在入侵物种的定殖概率。然而，大多数管理计划和研究工作未能明确承认繁殖压力的所有三个组成部分：大小、数量和风险 - 释放关系。目前尚不清楚未能指定这些组成部分中的一个或多个会如何影响管理计划在防止入侵物种建立方面的效力。此外，即使所有组件都得到确认和量化，目前也没有可用的数学工具来计算繁殖压力水平，以确保达到预定的、系统特定的目标建立概率。这里，当繁殖体压力的一个或多个组成部分未知时，我们通过对繁殖体压力的实际值使用参数不确定性分析来量化由此产生的建立概率的不确定性。此外，为了帮助制定明确设定繁殖体压力限制的管理计划，我们开发了繁殖体压力敏感性分析，用于确定繁殖体大小和数量（代表管理行动）所需的减少水平，以保持目标建立概率。我们表明，建立估计的精度高度依赖于所有三个繁殖压力分量的知识，其中建立概率的可能值范围可能会在没有完整规范的情况下变化超过 50%。此外，我们的敏感性分析表明，繁殖体的大小和数量可以单独或联合改变，以将定殖概率降低到目标水平以下。重要的是，我们的敏感性分析能够具体量化达到给定目标建立概率所需的繁殖体压力分量的降低程度。我们的研究结果表明，量化繁殖压力的三个组成部分应该是入侵物种预防的优先事项。此外，我们的敏感性分析工具可以以透明和定量的方式指导新入侵物种管理计划的制定。连同与降低繁殖压力的方法相关的成本信息，