Cascading impacts of overstory structure in managed forests on understory structure, microclimate conditions, and Ixodes scapularis (Acari: Ixodidae) densities.

Forest management practices designed to meet varied landowner objectives affect wildlife habitat and may interrupt the life-cycle stages of disease vectors, including the black-legged tick, Ixodes scapularis Say (Acari: Ixodidae). Ixodes scapularis transmits multiple pathogens including Borrelia burgdorferi, the causative agent of Lyme disease, which is the most common tick-borne disease in the United States. There is evidence that a range of active forest management practices (e.g., invasive plant removal, prescribed burning) can alter tick densities and pathogen transmission. However, few studies have investigated relationships between forest stand structural variables commonly manipulated by timber harvesting and tick ecology. Foresters may harvest timber to create certain forest structural conditions like the mean number of trees, or basal area, per hectare. This study used a spatially replicated experiment in a blocked design to compare forest stands with a range of overstory structures and document variations in the midstory, understory, and forest floor, as well as microclimate conditions within tick off-host habitat. Greater numbers of trees or basal area per hectare correlated with greater canopy closure but less understory cover, stabilized microclimate temperature, higher microclimate humidity, and greater I. scapularis nymph densities. A random forest model identified understory forest structure as the strongest predictor of nymph densities. There was no relationship between the number of trees or basal area per hectare and daily deer (Odocoileus virginianus Zimmermann) activity or nymphal infection prevalence. These findings provide a deeper understanding of tick-habitat associations within a forest stand and have the potential to inform forest management decisions.

A citizen science approach to investigate the distribution, abundance, and pathogen infection of vector ticks through active surveillance.

Tick-borne disease poses a growing public health burden in the United States and understanding the patterns of presence and density of infected vector ticks is key to developing and implementing effective public health management strategies. Citizen science has emerged as a highly effective means to generate data sets on the geographical distribution of tick species. But to date, nearly all citizen science studies of ticks are 'passive surveillance' programs in which researchers accept reports of ticks, together with either physical specimens or digital images, found opportunistically on people, pets, and livestock from community members for species identification and in some cases also tick-borne pathogen detection. These studies are limited because data are not collected systematically, making comparisons among locations and over time challenging, and introducing considerable reporting bias. In this study, we engaged citizen scientists in 'active surveillance' of host-seeking ticks, training volunteers to actively collect ticks on their woodland properties in an emergent region of tick-borne disease in the state of Maine, USA. We developed volunteer recruitment strategies, materials to train volunteers in data collection methods, field data collection protocols based on techniques used by professional scientists, and a variety of incentives to promote volunteer retention and satisfaction with their experiences, and we communicated research findings to participants. A total of 125 volunteers in 2020 and 181 volunteers in 2021 collected 7,246 ticks in southern and coastal Maine, including the American dog tick (Dermacentor variabilis, 4,023 specimens), the blacklegged tick (Ixodes scapularis, 3,092 specimens), and the rabbit tick (Haemaphysalis leporispalustris, 102 specimens). We demonstrated the feasibility of citizen scientists collecting ticks using active surveillance methods and found that volunteers were motivated to participate largely by their interest in the scientific problem and a desire to learn about ticks on their properties.

Collaborative Modeling of the Tick-Borne Disease Social-Ecological System: A Conceptual Framework.

Hard-bodied ticks have become a major concern in temperate regions because they transmit a variety of pathogens of medical significance. Ticks and pathogens interact with hosts in a complex social-ecological system (SES) that influences human exposure to tick-borne diseases (TBD). We argue that addressing the urgent public health threat posed by TBD requires an understanding of the integrated processes in the forest ecosystem that influence tick density and infection prevalence, transmission among ticks, animal hosts, and ultimately disease prevalence in humans. We argue that collaborative modeling of the human-tick SES is required to understand the system dynamics as well as move science toward policy action. Recent studies in human health have shown the importance of stakeholder participation in understanding the factors that contribute to human exposure to zoonotic diseases. We discuss how collaborative modeling can be applied to understand the impacts of forest management practices on ticks and TBD. We discuss the potential of collaborative modeling for encouraging participation of diverse stakeholders in discussing the implications of managing forest ticks in the absence of large-scale control policy.

Active Forest Management Reduces Blacklegged Tick and Tick-Borne Pathogen Exposure Risk.

In the northeastern USA, active forest management can include timber harvests designed to meet silvicultural objectives (i.e., harvesting trees that meet certain maturity, height, age, or quality criteria). Timber harvesting is an important tool in enhancing regeneration and maintaining forest health. It also has considerable potential to influence transmission dynamics of tick-borne pathogens, which are deeply embedded in the forest ecosystem. We conducted a 2-year study to test the hypotheses that recent timber harvesting impacts blacklegged tick density and infection prevalence in managed nonindustrial forests. We found that (1) recent harvesting reduces the presence of nymphal and density of adult blacklegged ticks, (2) recently harvested stands are characterized by understory microclimate conditions that may inhibit tick survival and host-seeking behavior, (3) capture rates of small mammal species frequently parasitized by immature ticks are lower in recently harvested stands compared to control stands with no recent harvest history. In addition, a 1-year pilot study suggests that harvesting does not affect nymphal infection prevalence. Collectively, our results demonstrate that forest structure and understory conditions may impact ticks and the pathogens they transmit via a range of mechanistic pathways, and moreover, active forest management may offer sustainable tools to inhibit entomological risk of exposure to tick-borne pathogens in the landscape.

An Agent-Based Model of Private Woodland Owner Management Behavior Using Social Interactions, Information Flow, and Peer-To-Peer Networks.

Privately owned woodlands are an important source of timber and ecosystem services in North America and worldwide. Impacts of management on these ecosystems and timber supply from these woodlands are difficult to estimate because complex behavioral theory informs the owner's management decisions. The decision-making environment consists of exogenous market factors, internal cognitive processes, and social interactions with fellow landowners, foresters, and other rural community members. This study seeks to understand how social interactions, information flow, and peer-to-peer networks influence timber harvesting behavior using an agent-based model. This theoretical model includes forested polygons in various states of 'harvest readiness' and three types of agents: forest landowners, foresters, and peer leaders (individuals trained in conservation who use peer-to-peer networking). Agent rules, interactions, and characteristics were parameterized with values from existing literature and an empirical survey of forest landowner attitudes, intentions, and demographics. The model demonstrates that as trust in foresters and peer leaders increases, the percentage of the forest that is harvested sustainably increases. Furthermore, peer leaders can serve to increase landowner trust in foresters. Model output and equations will inform forest policy and extension/outreach efforts. The model also serves as an important testing ground for new theories of landowner decision making and behavior.

Building trust in natural resource management within local communities: a case study of the Midewin National Tallgrass Prairie.

Communities neighboring federally protected natural areas regularly weigh the costs and benefits of the administering agency's programs and policies. While most agencies integrate public opinion into decision making, efforts to standardize and formalize public involvement have left many local communities feeling marginalized, spurring acrimony and opposition. A significant body of research has examined barriers to effective public participation as well as strategies for relationship building in planning processes; many of which point to trust as a key factor. Trust is especially tenuous in local communities. This paper explores perceptions of trust, expectations for management, as well as constraints to building trust. In-depth interviews were conducted with 21 community members and USDA Forest Service personnel at the Midewin National Tallgrass Prairie in northeastern Illinois. The interviews revealed that trust is perceived as important to effective management. Distinct expectations for management outcomes and processes emerged, including the values, knowledge, and capacity demonstrated in management decisions and actions and opportunities provided for communication, collaboration, and cooperation within the agency-community relationship. The case study identified several constraints to building trust, including competing values, knowledge gaps, limited community engagement, and staff turnover.