The joint effect of land use and climate change on biodiversity in a highly fragmented landscape

Background/Question/Methods

Climate and land use change are known to be key drivers of change in terrestrial ecosystems. These drivers occur at contrasting spatial and temporal scales, and the way their effects on biodiversity interact at the regional scale remains poorly known. The goal of this study was to determine how climate and land use change jointly impact habitat availability and habitat fragmentation at the regional scale. Our study takes place in Quebec, in the region of Montreal.  This is a highly fragmented landscape dominated by agro-forest ecosystems Climate change leads to species range shifts and changes in habitat quality. Land use change drives both: (i) habitat availability through landscape composition and (ii) habitat fragmentation though landscape composition and configuration. We ran a stochastic land cover model based on (i) a top-down, demand-driven, change in land area and (ii) a bottom-up local conversion process, under different scenarios (a hundred run per scenario). These scenarios covered a spectrum of possible futures ranging from urban sprawl to strong environmental protection. For a number of target species, we derived habitat suitability layers and calculated the associated structural connectivity of the landscape. We then compared habitat availability and habitat fragmentation between the runs and scenarios.          

Results/Conclusions

The target species were selected to represent the range of biodiversity in the region in terms of habitat requirements, dispersal abilities and population dynamics. As expected species responded differently to climate and land use change in the study area. Land use and climate change seemed to interact either positively or negatively to both habitat availability and fragmentation depending on the species. On average, habitat availability strongly decreased through time, except under the environmental protection scenario. Similarly, habitat fragmentation mainly increased through time, but the level of fragmentation varied strongly between runs for each scenario. This suggests that not only landscape composition but also landscape configuration defines species’ habitat. To conclude, at the regional scale, policies developed to preserve biodiversity and ecosystems should: (i) integrate modelling approaches that incorporate both land use and climate change, and (ii) incorporate landscape configuration in land use change scenarios.