Can restoration of afforested peatland regulate pests and disease?

Abstract

Summary1. Government policies are driving landscape-scale changes in land use to provide ecosystem services; but there may be unconsidered cascading effects. A major land use change targeted for regulating climate and biodiversity is peatland restoration. This will cause changes in vegetation and, potentially, keystone species such as large herbivores, which are the main hosts to Ixodes ricinus (L.) ticks, the most important vector of disease-causing pathogens in Europe.2. This study tested the impact of restoring peatlands from conifer forestry on Ixodes ricinus abundance and explored the likely mechanisms. Large-scale surveys of Ixodes ricinus, vertebrate herbivores and vegetation were conducted in adjacent areas of forest, bog and areas felled 5-13 years previously. 3. Questing tick abundance was greatest in forest and almost absent from blanket bog, with intermediate numbers in felled areas, where ticks were more abundant in young than in old felled areas. 4. The likely mechanisms for these variations in tick abundance were deer habitat preferences (bog was the least preferred habitat) and ground vegetation height or canopy cover, which are generally associated with alternative tick hosts and micro-climates that aid tick questing and survival. 5. Synthesis and applications. Felling conifer forest to restore peatlands could produce a dramatic decline in tick abundance throughout the restoration process, with implications for disease risk. Therefore, a further ecosystem service of peatlands in addition to climate, biodiversity and water regulation is regulating pests and disease. Deer management and procedures that speed up the restoration process are likely to enhance the effect during the intermediate stages.

Identifying Environmental Risk Factors for Louping Ill Virus Seroprevalence in Sheep and the Potential to Inform Wildlife Management Policy

“…Thus, although the association between red deer densities and LIV seroprevalence was statistically weak and included a lot of variation, the fact that we found a significant association at all could be indicative of a much stronger association in reality. While red deer do not transmit LIV between ticks (42) deer of various species are often the key drivers of Ixodid tick populations in both Europe (7,20,43,44) and North America (45)(46)(47)(48)(49)(50), including red deer in Scotland (10,19,21,24,40). Because of this, several theoretical models of the LIV system in Scotland predict a key role of deer in the persistence of LIV in ticks and both red grouse and sheep systems (51)(52)(53)(54).…”

“…Thus, if wildlife hosts and other abiotic factors are more important risk factors than the sheep themselves, we predict higher LIV seroprevalences in heather moorland than in lowland improved grassland and in areas with higher densities of deer and a warmer climate. Woodland habitats are often associated with higher I. ricinus tick densities than open habitats, due to generally higher tick host densities and mild, humid microclimate created by woodland canopies (10,19,(23)(24)(25). Indeed, sheep tick burdens and tick densities on sheep pastures can be higher if they are closer to woodlands or have more tree cover (26).…”

Modelling edge effects of mature forest plantations on peatland waders informs landscape‐scale conservation

“…For example, hydrological and habitat effects of forestry on adjacent blanket bog in the Flow Country extend up to 40 m from plantation boundaries, at least in the first few decades (Shotbolt, Anderson & Townend ), and could affect prey availability for breeding birds. Forestry also holds high densities of ticks Ixodes ricinus relative to blanket bog (Gilbert ), and although the form of the relationship between tick densities and distance to forest edges remains unknown, ticks can infest chicks of moorland‐breeding waders (Newborn et al . ).…”

Modelling the seasonality of Lyme disease risk and the potential impacts of a warming climate within the heterogeneous landscapes of Scotland

“…Nymphs have been shown to be the stage causing most Lyme disease cases in people [46,47]. Furthermore, we focused on simulations in woodlands, as field studies have shown that many more ticks have been observed in forests than open habitats [48].…”