Influence of DEM Uncertainty on the Individual-Based Modeling of Dispersal Behavior: A Simple Experiment

Abstract

It is generally accepted that the perceptual range of an animal towards different landscape elements can influence its movement through heterogeneous landscapes. Dispersal movement is a determining factor in the spread of species as well as metapopulation dynamics. An individual-based, spatially explicit model with an isotropic perceptual range was used to simulate the dispersal movement of grey squirrels (Sciurus carolinensis). The effects of anisotropic perceptual range are modeled by incorporating digital elevation model (DEM) data in the representation of the landscape so that line-of-sight analysis can be used to arrive at an anisotropic perceptual range. This simple experiment uses Monte Carlo simulation to study the effect DEM uncertainty may have on the simulated movements of individuals. Mean displacement distance and straightness index are used to measure the effect of DEM uncertainty on the walks taken by individuals. The habitat patch terminus for each individual was used to determine if individuals would end in the same patch for each simulation. Two perceptual ranges of differing extent were used. For both measures of movement behavior they vary more when the larger perceptual range is used. Results showed that the extent as well as the anisotropic nature of the perceptual range could affect an individual’s simulated behavior. The larger perceptual range more often resulted in greater deviation from baseline results. This experiment suggests that DEM uncertainty can have an effect on spatially explicit individual-based movement models.