Predicting the repercussions of anthropogenic landscape modifications on the biota using species focused adaptable GIS and spatial dynamic models

Habitat fragmentation and species invasions are increasingly threatening the survival of native species worldwide. In this context, a set of tools and approaches was developed to help (1) improve our understanding of species relationships to the landscape and predict their habitat usage, population variations and patterns of spread in fragmented landscapes and (2) identify and address potential environmental risks associated with land-use planning. The approach consisted in the development of computer-based spatial dynamic models and GIS methods to (1) identify, for an habitat specialist, suitable habitat patches within landscapes and determine habitat connectivity and metapopulation sizes; (2) model long-term population variations and detailed movement behaviors of habitat-specialist species in heterogeneous landscapes; (3) identify, for an adaptable species, potentially usable territories and estimate how adaptations might shape and modify species habitat occupancy; and (4) determine the potential spreading pattern of an invasive plant species and test potential management strategies. Each of these approaches was designed to be adaptable for various species and incorporates user-defined life history characteristics, habitat needs or movement behaviors. We showed, through the development and testing of these tools, that: (1) considerations of the spatial arrangement and structure of habitat patches combined with species life history characteristics may provide a better tool than considerations of altered areas alone, to estimate the consequences of habitat loss and fragmentation on animal populations; (2) changes in land-use resulting in limited habitat losses could nonetheless lead to significant reductions in population sizes of a species within a landscape; (3) minor changes in species habitat requirements or movement behaviors have important repercussions on the amount of suitable habitat it can access; and (4) modifications in plant species life history characteristics (occurrence of sexual reproduction) could drastically increase their capacity to spread across fragmented landscapes. The application of these tools to fictitious species over different landscapes also illustrated their capacity to be used to identify and map species-suitable habitat and determine potential movement or spreading patterns between patches. Finally the potential use of these tools for the testing of hypotheses to improve the understanding of species landscape interactions was stressed.