Can Restoration of Fire-Dependent Ecosystems Reduce Ticks and Tick-Borne Diseases?

The exclusion and suppression of fire in eastern US forests over the past century has led to changes in the composition, structure, and function of fire-dependent landscapes. Dry pine forest communities that once burned on a frequent interval have seen encroachment of fire intolerant and other mesic species in the absence of fire. This process, called forest mesophication, has been widely documented across Eastern US forests. In addition, forest fragmentation, climate change, and the increased prevalence of white-tailed deer have altered landscape condition. The degradation of these landscapes due to fire suppression and other factors has likely contributed to the increase in tick populations and the transmission of tick-borne diseases to humans.

Current strategies for tick-borne disease control, which mainly focus on tick bite prevention, are insufficient to address the increasing rates of tick-borne pathogen transmission. There is a need for integrated tick management approaches that can be implemented at a broad scale. In this project, researcher propose an alternative, ecologically based tick population control strategy: restoring fire-dependent ecosystems through the application of prescribed fire. By mimicking natural fire regimes, researchers demonstrate how prescribed fire can reverse mesophication, restore forest structure, and create conditions unfavorable for ticks. Prescribed fire also has additional benefits such as mitigating wildfire risks and promoting ecosystem health.

Utilizing prescribed fire as an ecological restoration tool offers a promising approach to reduce tick populations and mitigate tick-borne diseases. By understanding the ecological role of fire and incorporating prescribed burning into tick management strategies, we can take proactive measure to protect public health and restore fire-dependent landscapes. However, continued research, collaboration, and public engagement are crucial for successfully implementing prescribed fire as part of comprehensive tick management efforts.

Key Findings

• The exclusion of fire in eastern US forests over the past century has caused significant changes in forest conditions and processes.
• Restoring fire-dependent ecosystems across eastern US forests through prescribed fire may have public health benefits by reducing tick populations and disease transmissions.
• Understanding the impact of fire exclusion, landscape changes, and the ecology of ticks is crucial for developing effective strategies to reduce tick populations and mitigate tick-borne diseases; prescribed fire can be a valuable tool in restoring fire-dependent ecosystems and therefore controlling tick habitat and populations.
• Fire regime characteristics such as fire intensity, severity, seasonality, frequency, and patterning of fire effects can impact tick habitat quality and use; more research is needed to incorporate tick population control into forest management strategies.

Approach

This research focuses on comparing tick populations and fire effects at the Northern Research Station’s Silas Little Experimental Forest and in the surrounding area of the New Jersey Pineland National Reserve. Contrary to many eastern landscapes, the New Jersey Pinelands has maintained a rich history of fire management and landscape-scale prescribed burning for public safety and ecological purposes throughout the past century and continues to today, providing a unique opportunity for replicated research on fire and ticks across many forests.

Researchers have been collecting ticks, measuring vegetation and detritus that ticks live in, and analyzing microclimates at 27 stands across the landscape that reflect a range of recent prescribed fire conditions as well as unburned forest conditions. The researchers are comparing tick population and disease prevalence estimates with tick habitat characteristics that are directly impacted by prescribed fire, including temperature and moisture conditions and the supply of physical structure required by ticks for hiding and for optimizing their chances of encountering a host. With their experimental design, researchers are also able to examine how frequency and severity of fire play into the effects they observe.

Outcomes

In 2022, the team published a comprehensive literature review describing the historic, physical, and ecological basis of prescribed fire as a socially acceptable, ecologically sound approach for ticks. In October 2022, the team completed its fourth year of field work in the New Jersey Pine Barrens. Preliminary results of the team’s field data showed a large initial decrease in ticks that is proportional to treatment severity in the first year following burning. Researchers found that treatment quality (e.g., Low, Moderate, or High Severity) caused varying deviations in forest structure and microclimates when compared to fire excluded areas. These changes have persisted through all 4 years of the study as have reductions in ticks. Interestingly, over 95 percent of all the ticks in all years of the study were lone star ticks (Amblyomma americanum), rather than blacklegged ticks (Ixodes scapularis), which were thought to be more common in the study area. The blacklegged ticks that were found were almost exclusively from fire-excluded areas.

These preliminary results have been presented at local universities, regional land manager meetings, and to land management agencies, with additions manuscripts on the study currently under way.