A complex-systems approach to improve understanding of the biodiversity-landscape structure relationship

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We are currently experiencing a global biodiversity crisis. Adorning front pages of international newspapers is the news that 25% of species are listed as threatened. In addition to global environmental change issues such as climate change, invasive species introductions and wildlife crime, the way we manage landscape is also having a negative effect. While it almost seems like common sense that reducing the amount of natural habitat will negatively impact wildlife, what is less clear is how the spatial arrangement of any remaining natural land cover factors in. The breaking apart of areas of natural land independent of the change in the amount is known as fragmentation. However, our understanding of the effects of fragmentation is widely debated and lacks a consistent evidence base. If we look at individual patches of natural land, we are likely to conclude that smaller patches contain fewer individuals and species, and that those species may be those that are less sensitive to what is happening outside of the patch. However, if we look at a whole landscape, made up of multiple small patches, the picture is more complicated. Each small patch may inhabit few species, but the fact they are isolated from each other could mean that there are differences in those species among the patches - perhaps because there is less competition between species. We also need to consider what is between those patches. Forest that has been cleared for low intensity agriculture may open up some different habitat types and therefore have a positive effect on biodiversity. On the other hand, forest cleared for roads and urban developments will likely pose a greater threat as it will limit the movement of individuals through behaviour change and increased mortality. Human intervention can both impede and assist dispersal depending on how habitat is fragmented and what it is fragmented by. In the proposed research, I will bring together research at various scales - from looking at characteristics of individual patches, to how this relationship manifests at the landscape scale and broader. I will consider this from a functional perspective - how do the impacts differ depending on whether we look at large carnivores or small grain-eating birds? I will also consider how the impacts change depending on what the natural habitat has been fragmented by. This is a multiscale problem, that requires a complex systems approach. A complex systems approach is one which allows us to consider how the constituent parts of a system work together to create a result which we may not have seen by only looking at each part individually.