Abstract
The largest land use change in Europe is woodland expansion, through planting and natural regeneration. Unforeseen consequences of this could include changes in environmental hazards, such as exposure to parasites and pathogens. Tick-borne Lyme disease is the most prevalent tick-borne disease in the northern hemisphere and is often associated with woodlands. Therefore, to inform the planning and management of expanding woodlands, we test how land covers that reflect different types and stages of the woodland expansion process, along with their deer management, impact tick densities and Lyme disease hazard (density of infected nymphs). We also test whether differences in rodent abundance play a mechanistic role in explaining differences in Lyme disease hazard. In Northwest Scotland, a touristic area undergoing woodland expansion, we recorded deer management, rodent densities, Ixodes ricinus nymph densities, pathogen prevalence and Lyme disease hazard between open moorland, young pine and mature pine, and birch and spruce. These represent pre-, early and late stage woodland establishments, and the three woodland types in the region. Rodents, ticks, pathogen prevalence and Lyme disease hazard were generally lowest in moorland and young pine and highest in mature woodland, especially birch, although variability was high. Deer management reduced tick densities and, marginally, Lyme disease hazard. There was insufficient evidence for rodents increasing Lyme disease hazard, but rodents augmented tick densities and the most abundant Lyme disease pathogen was that transmitted by rodents. Practical implication. woodland expansion could, once mature, eventually lead to higher tick densities, pathogen prevalence and Lyme disease hazard. Importantly, an environmental solution could be to control deer populations.
Dr Sara Gandy
Research Associate
My research primarily focuses on understanding the ecological drivers of tick-borne diseases to provide insights on the mechanisms involved in transmission cycles, especially on the interactions between ticks, hosts and pathogens. My research includes investigating the impacts of environmental changes (woodland restoration, rewilding) and host community composition (deer, rodent and birds) on tick-borne diseases risks in the UK. Some of my findings uncovered an opposing effect of deer densities on Lyme disease hazard through their positive effects on tick density and negative effects on infection prevalence. I also published work looking at spatiotemporal changes in tick distribution using passive surveillance data and I have been leading the National Tick Survey, which involves collaborating with stakeholders in thirty National Parks and recreational areas to collect ticks and test them for various tick-transmitted pathogens between 2021 and 2024. The goal is to understand disease hazard and temporal variation in areas visited by members of the public and deliver tick awareness messages.