University of Washington Seattle, Washington, United States
Abstract: Estimates of population spread and growth rates are valuable for optimally allocating management efforts to control invasive species. Novel insights into invasive population dynamics can be gained from spatially structured removal data, as well as other types of monitoring data collected during a management program. Of greatest interest to managers, monitoring data can also be used to update management decisions based on information gained from the data, in an iterative process known as adaptive management. While monitoring data are essential for adaptive management, data collection can be costly and time intensive, and involves the difficult task of balancing resources allocated towards monitoring against resources allocated towards control. To demonstrate how resource allocation can be informed by data, we developed models using multiple data sources to estimate growth, spread, and removal efficacy for invasive flowering rush, Butomus umbellatus, an invasive species in the Columbia River, United States. We then developed spatial simulations to explore optimal adaptive management approaches for flowering rush and conducted a value of information analysis to evaluate the value of sample information for different monitoring data types, which included traditional detection/non-detection data and removal data. Population dynamics and management outcomes were simulated for a fixed time and the total biomass of flowering rush and river length occupied was assessed. We compared the management outcomes (e.g., final biomass) of scenarios that incorporated both removal data and detection/non-detection data to scenarios with only removal data. Next, the ability of different monitoring and management scenarios to produce accurate abundance and spatial distribution measures of flowering rush was determined. In addition to potentially informing flowering rush management and monitoring, the modeling framework presented here could be applied to a variety of invasive species contexts to reveal the expected management benefits of obtaining different monitoring data streams.