Species Distribution - Species Distribution Models

Species Distribution Models

Species distribution can now be potentially predicted based on pattern of biodiversity at spatial scales. A general hierarchical model can integrate disturbance, dispersal and population dynamics. Based on factors of dispersal, disturbance, resources limiting climate, and other species distribution, predictions of species distribution can create a bioclimate range, or bioclimate envelope. The envelope can range from a local to a global scale or a density independence to density dependence. The hierarchical model takes into consideration of requirements and impacts or resources as well as local extinctions in disturbance factors. Models can integrate the dispersal/migration model, the disturbance model, and abundance model. Species distribution models (SDMs) can be used to assess climate change impacts and conservation management issues. Species distribution models include: presence/absence models, the dispersal/migration models, disturbance models, and abundance models. A prevalent way of creating predicted distribution maps for different species is to reclassify a land cover layer depending on whether or not the species in question would be predicted to habit each cover type. This simple SDM is often modified through the use of range data or ancillary information- such as elevation or water distance.

Recent studies have indicated that the grid size used can have an effect on the output of these species distribution models. The standard 50x50 km grid size can select up to 2.89 times more area than when modeled with a 1x1 km grid for the same specie. This has several effects on the species conservation planning under climate change predictions (global climate models- which are frequently used in the creation of species distribution models- usually consists of 50–100 km size grids) which could lead to over-prediction of future ranges in species distribution modeling. This can result in the misidentification of protected areas intended for a species future habitat.