Stepping Stone Path

The objective of the study for which data has been deposited is two-fold: first, it aims to design a spatial optimization model for stepping stone corridors and a computationally efficient method for its solution. Then it demonstrates a concrete example of use of the model in application to a real-world conservation project.
As spatial planning and decision on conservation corridors tend to involve multiple—often subjective and uncertain—factors ranging from environmental and economic to social and political, actual conservation corridors may not be fully connected but composed of isolated habitat fragments. To offer computational support in planning such ‘stepping stones’ corridors, we design and implement a raster-based GIS model that characterizes and searches for an optimal sequence of isolated patches as stepping stones across a mosaic of land cover types. The model is unique in two aspects. First, it simultaneously selects stepping stones to be included and a path through which they are to be traversed, which collectively form a corridor. The latter would be useful information in planning on where to perform certain actions (e.g., planting) to encourage organisms to follow the corridor. Second, unlike existing least-cost path models, it does not require the quantification of land covers in terms of their suitability (or cost) for being included in the corridor, but only requires the rank-ordering of them. This would not eliminate all the subjectivity or uncertainty involved but reduce it substantially. We apply the model to a conservation project in Rwanda, that aims to increase the connectivity of two national parks via the establishment of a hedgerow of native plants for dispersal of pollinator birds. Results suggest that the model allows for a rapid first delineation of candidate routes for stepping stone corridors and facilitates the early exploratory stages of conservation projects.