Better Defining Habitat Patches to Improve Spatially Explicit Modelling Outputs

Abstract Simulation modelling is becoming increasingly widespread to evaluate population biological responses to global changes such as habitat loss or habitat fragmentation. To produce reliable results, this approach requires great care in setting up the model. In the case of spatially explicit modelling, this involves all spatial parameters, but particularly habitat patches, the spatial unit at which demographic processes and dispersal occur. We developed a method to delineate habitat patches that are biologically relevant for simulating demographic processes of the species of interest. Based on the Voronoï tessellation principle, this fully automatized method splits contiguous tracts of habitat such that the resulting patches meet the required surface (e.g. average size of one or several home ranges of the study species). We investigated the consequences of patch definition on modelling outputs (population density, habitat occupancy, dispersal success, straightness and distances), comparing predictions when modelling was based on patches as they are currently usually defined (contiguous sets of habitat cells) with our species‐adapted definition. To do so, we used the spatially explicit individual‐based modelling platform, RangeShifter, applied to five study areas in the south of France, taking the European red squirrel as an example. Our results showed that our framework was effective in dividing large contiguous tracts of habitat into smaller, species‐adapted patches. They also showed that simulation outputs strongly depended on habitat patch delimitation, with effects being mostly consistent among the different landscapes we tested. We also show that mean dispersal distances and population densities required species‐adapted patch definition to be as close as possible to empirical data. Finally, in order to be able to use predicted data for conservation or reintroduction purposes, species‐adapted parameters need to be adjusted after having chosen a species‐adapted definition of habitat patches.