Visual-quality impacts of forest pest activity at the landscape level: A synthesis of published knowledge and research needs

Given the growing importance of forest-management strategies which seek to emulate natural disturbance patterns, and the increased incidence of pest epidemics in some parts of North America, there is surprisingly little published research on perceived visual quality of pest infestations, especially, at the landscape level (middleground viewing distance). Much of the literature that does exist focuses on the visual impact of beetles (Dendroctonus spp.) or gypsy moth (Lymantria dispar). This paper reviews the work published to date and distills key points and research priorities emerging from it. Visual-quality ratings generally decrease significantly as pest damage increases in the middleground landscape. Some studies have identified quite low thresholds (in terms of the area of the visible landscape affected by pest activity), below which perceived visual quality drops significantly with increasing visible pest damage, and beyond which, additional negative visual impacts of increasing damage appear to be modest. However, reductions in visual quality due to pest attack may be outweighed by high visual quality of the overall scene. Low levels of beetle damage may even enhance the visual quality of a landscape temporarily. Results are not clear on the effect of information about pest infestations on respondents’ visual-quality ratings. Some studies show that informed respondents consider visual quality of affected scenes to be lower than do uninformed respondents, but this may reflect the way in which the information was delivered. A conceptual framework is suggested which relates the existing research to knowledge gaps and future research priorities, not only on visual-quality effects of pest infestations but also on related public perceptual responses and other disturbance types.