In review of:
Johnson, R., & Greenwood, S. (2019). Assessing the ecological feasibility of reintroducing the Eurasian lynx (Lynx lynx) to southern Scotland, England and Wales. Biodiversity and Conservation, 29(3), 771–797. doi: 10.1007/s10531-019-01909-2
As the research conducted and presented in this paper is concurrent with the pillar of landscape ecology, the main goal presented was to provide a preliminary “assessment of the ecological feasibility of lynx reintroduction in Britain, outside of the Scottish Highlands,” (Johnson & Greenwood, 2019, p. 772) where all other population viability assessments for the reintroduction of the Eurasian lynx (Lynx lynx) have been conducted so far. The purpose of this research is to restore natural flora and fauna processes within British ecosystems, as the Lynx lynx has been extinct in Britain since medieval times, a lack of predators has led to an imbalance producing record high deer population densities, negatively affecting biodiversity and inhibiting flora regeneration. The researchers aim to present potential Lynx lynx habitat areas, identify certain hypotheses that can be further tested in studied reintroduction trials and projections or solutions to scenarios that can improve the chance of success in this paper. The logic behind the Lynx lynx reintroduction as opposed to other large carnivores is that it is most viable due to its smaller size and lower livestock predating tendencies. However, the Scottish Natural Heritage (SNH) states that reasons for extinction should no longer be present for a viable reintroduction, but as habitats are being restored with reforestation and a dramatic reduction in the demand for furs, the reasons for their extinction are no longer present or are dramatically reduced. This study is based on several other similar studies carried out before it in the Scottish Highlands, and thus uses the same equations, kinds of spatial analysis, and compares them to existing long term studies of Lynx lynx conducted in the Jura mountains and Norway to compare accuracy.
The spatial analysis first consisted of the creation of buffers representing woodland type (mature mixed forest, shrub land, young trees, low density) and size. Where they overlapped, they created habitat patches, which were then overlaid with waterbodies and urban areas to remove or split any patches intersected by these features. All patches under 45km2 and/or containing less than 38% woodland cover were removed. Next, a connectivity assessment was carried out by identifying least cost paths derived for each habitat path, connecting it to the most easily accessible patch. There are a number of suggested rules of thumb for the Lynx lynx reintroduction, including a minimum area of 10,000km2 to support a minimum population of 200 lynx, and least cost paths between habitats as maximum converted cost of 2700, both of which are based on several academic studies with the latter coming from a long term study of Lynx lynx populations in the Jura mountains, where there is large development. Thus, as neither Switzerland or Norway could directly apply to the British context, sensitivity analysis was conducted on the LCP threshold by increasing and decreasing it by 10% and 20%. Lastly a population viability analysis was conducted using VORTEX 10.3.5.0 to simulate long-term feasibility based on the Jura Mountain study, the Scandinavian study, and an intermediate scenario.
The sensitivity analysis ended up having a major effect on the ending results, as there was an increase in LCP threshold, multiple habitats morphed into a singular one increasing the size by 19.1% and 23.7% respectfully. While a total of 63 separate habitat paths were identified there were only two (debatably three) habitat regions which would be conducive to long term feasibility in South Uplands & Kielder, Southeast England, and potentially Thetford Forest. I believe that because Johnson & Greenwood conducted their research around other successful studies, and performed sensitivity analysis, their methodological approach was appropriate, as I’ve seen other research done on habitats and canopy cover using the same buffer tool, and LCP are incredibly useful to testing connectivity as opposed to LDPs.
Overall, the results of the study only suggest uncertain ecological feasibility of reintroducing the Lynx lynx, as there was not necessarily 10,000km2 of a singular habitat patch, rather it was fragmented between different regions. Places with high deer densities had relatively high subadult and adult morality rates and would likely not be able to sustain a population for long term, however, there remains possibility for greater connection networks, and thus landmass, if overpasses or underpasses are available for Lynx lynx to cross highways/tracks that were deemed unfeasible before. To me, this also validates their claims, as they have only provided an indication of where ecological conservation should be focused on in terms of reintroduction outside of the Scottish Highlands, recognizes the inaccuracy in their deer population data, recognizes the different British context from its reference studies, understands the human/urban variable that creates uncertainty in reintroduction, conducted multiple sensitivity analysis that had direct impact on all their results which is combined to create the most accurate predictions, and presented potential infrastructure solutions to improving connectivity between habitat patches. Definitively, I give this paper a 9.5/10 because I found it to be incredibly interesting as it used spatial tools that I have in the past and the results seemed to be well analyzed and valid.