Habitat patches providing south-north connectivity are under-protected in a fragmented landscape

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Thomas T. P. Travers and Jenny A. Hodgson, Department of Evolution, Ecology, and Behaviour, University of Liverpool, Liverpool, United Kingdom, Jamie Alison, UK Centre for Ecology & Hydrology, Bangor, United Kingdom, Sarah D. Taylor and Humphrey Q. P. Crick, Natural England, York, United Kingdom

Background/Question/Methods
As species’ ranges shift to track climate change, conservationists increasingly recognise the need to consider connectivity when designating protected areas (PAs). In fragmented landscapes, certain habitat patches can be key to connectivity, but methods for their identification are not widely used. Additionally, previous research has focused on the connectivity of PA networks, rather than the connectivity of the habitat networks those PAs exist to conserve. As a result, areas of habitat that play a vital role in network connectivity may have been overlooked in our designation systems, leaving their connectivity vulnerable. Here, we assess the capacity of England’s PAs to secure long-distance connectivity in a suit of 16 national conservation priority habitats. We use Condatis, a landscape-scale decision-support software with a basis in circuit theory, to identify “high-flow” habitat patches critical to long-distance connectivity and range expansion under climate change. To better understand and conserve patches, we ask: (1) To what extent are high-flow patches represented in England’s current PA network? (2) How is the protection and/or high-flow status of habitat patches related to their area? (3) How much extra network connectivity could be conserved through a targeted protection of high-flow patches?
Results/Conclusions
We find that a concerning proportion of high-flow patches are left out of existing PAs. Across the habitats included in the study, an average of 13.6% less of a habitat network’s connectivity is protected than its area. GLMs including both area and flow as predictors of protection status found predominantly negative effects for flow, despite also finding positive effects for patch area, which is positively correlated with flow. We conclude that the legacy of past protection decisions has left habitat-specialist species vulnerable under climate change. This situation is likely mirrored in may countries, which have similar guiding principles and practical considerations for habitat protection. Addressing the under-protection of connectivity requires specific planning tools that can account for the directions in which species may shift. Our connectivity-led reserve selection procedure, which is applicable to habitats and species across the globe, was able to protect on average 32.5% more connectivity in these landscapes with just a 10% increase in the area protected. We feel that these results show promise in filling such a role, and could form part of a nuanced prioritisation process, accounting for land-use changes, habitat quality, climate suitability, and landscape connectivity.