Abstract: Conservation investments are increasingly evaluated on the basis of their return on investment (ROI). Conservation ROI analysis quantitatively measures the costs, benefits, and risks of investments so conservancies can rank or prioritize them. This paper surveys the existing conservation ROI and related literatures. We organize our synthesis around the way studies treat recurring, core elements of ROI, as a guide for practitioners and consumers of future ROI analyses. ROI analyses involve quantification of a consistent set of elements, including the definition and measurement of the conservation objective as well as identification of the relevant baselines, the type of conservation investments evaluated, and investment costs. We document the state of the art, note some open questions, and provide suggestions for future improvements in data and methods. We also describe ways ROI analysis can be extended to a broader suite of conservation outcomes than biodiversity conservation, which is the typical focus.

Abstract: This study examines the spatial nature of optimal bioinvasion control. We develop a spatially explicit two-dimensional model of species spread that allows for differential control across space and time, and we solve for optimal spatial-dynamic control strategies. We find that the optimal strategies depend in interesting ways on the shape of the landscape and the location, shape, and contiguity of the invasion. For example, changing the shape of the invasion or using landscape features to reduce the extent of exposed invasion edge can be an optimal strategy because it reduces long-term containment costs. We also show that strategies should be targeted to slow or prevent the spread of an invasion in the direction of greatest potential long-term damages. These spatially explicit characterizations of optimal policies contribute to the largely nonspatial literature on controlling invasions and our general understanding of how to control spatial-dynamic processes.