Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, 08901, USA.
Invasion Science & Wildlife Ecology Lab, University of Adelaide, Adelaide, South Australia, 5005, Australia.
Ecol Appl. 2021 Jun;31(4):e02314. doi: 10.1002/eap.2314. Epub 2021 Apr 7.
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.
有大量证据表明，降低繁殖体压力可以显著降低潜在入侵物种的建立概率。然而，大多数管理计划和研究工作都未能明确承认繁殖体压力的三个组成部分：大小、数量和风险释放关系。目前尚不清楚未能具体说明这些组成部分中的一个或多个部分会如何影响管理计划在防止入侵物种建立方面的效果。此外，即使承认并量化了所有组成部分，目前也没有数学工具可用于计算确保达到预定的、特定于系统的建立概率的繁殖体压力水平。在这里，我们通过对繁殖体压力的实际值进行参数不确定性分析，量化了当一个或多个繁殖体压力组成部分未知时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，我们开发了一种繁殖体压力敏感性分析，用于确定繁殖体大小和数量（代表管理措施）所需的降低水平，以维持目标建立概率。我们表明，建立估计的精度高度依赖于对所有三个繁殖体压力组成部分的了解，其中建立概率的可能值范围在没有完整说明的情况下可能会变化超过 50%。此外，我们的敏感性分析表明，繁殖体大小和数量可以独立或结合使用，将建立概率降低到低于目标水平。重要的是，我们的敏感性分析能够具体量化需要降低繁殖体压力组成部分的多少才能达到给定的目标建立概率。我们的研究结果表明，量化繁殖体压力的三个组成部分应该是未来预防入侵物种的优先事项。此外，我们的敏感性分析工具可以用于以透明和定量的方式指导新的入侵物种管理计划的制定。结合与降低繁殖体压力相关的成本信息，我们的工具可用于确定最具成本效益的方法来防止入侵物种的建立。
